1
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Figueroa-Bossi N, Fernández-Fernández R, Kerboriou P, Bouloc P, Casadesús J, Sánchez-Romero MA, Bossi L. Transcription-driven DNA supercoiling counteracts H-NS-mediated gene silencing in bacterial chromatin. Nat Commun 2024; 15:2787. [PMID: 38555352 PMCID: PMC10981669 DOI: 10.1038/s41467-024-47114-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 03/19/2024] [Indexed: 04/02/2024] Open
Abstract
In all living cells, genomic DNA is compacted through interactions with dedicated proteins and/or the formation of plectonemic coils. In bacteria, DNA compaction is achieved dynamically, coordinated with dense and constantly changing transcriptional activity. H-NS, a major bacterial nucleoid structuring protein, is of special interest due to its interplay with RNA polymerase. H-NS:DNA nucleoprotein filaments inhibit transcription initiation by RNA polymerase. However, the discovery that genes silenced by H-NS can be activated by transcription originating from neighboring regions has suggested that elongating RNA polymerases can disassemble H-NS:DNA filaments. In this study, we present evidence that transcription-induced counter-silencing does not require transcription to reach the silenced gene; rather, it exerts its effect at a distance. Counter-silencing is suppressed by introducing a DNA gyrase binding site within the intervening segment, suggesting that the long-range effect results from transcription-driven positive DNA supercoils diffusing toward the silenced gene. We propose a model wherein H-NS:DNA complexes form in vivo on negatively supercoiled DNA, with H-NS bridging the two arms of the plectoneme. Rotational diffusion of positive supercoils generated by neighboring transcription will cause the H-NS-bound negatively-supercoiled plectoneme to "unroll" disrupting the H-NS bridges and releasing H-NS.
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Affiliation(s)
- Nara Figueroa-Bossi
- Université Paris-Saclay, CEA, CNRS, Institut de Biologie Intégrative de la Cellule (I2BC), Gif-sur-Yvette, France
| | - Rocío Fernández-Fernández
- Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Sevilla, Spain
| | - Patricia Kerboriou
- Université Paris-Saclay, CEA, CNRS, Institut de Biologie Intégrative de la Cellule (I2BC), Gif-sur-Yvette, France
| | - Philippe Bouloc
- Université Paris-Saclay, CEA, CNRS, Institut de Biologie Intégrative de la Cellule (I2BC), Gif-sur-Yvette, France
| | - Josep Casadesús
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla, Spain
| | | | - Lionello Bossi
- Université Paris-Saclay, CEA, CNRS, Institut de Biologie Intégrative de la Cellule (I2BC), Gif-sur-Yvette, France.
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2
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Lukose B, Maruno T, Faidh M, Uchiyama S, Naganathan A. Molecular and thermodynamic determinants of self-assembly and hetero-oligomerization in the enterobacterial thermo-osmo-regulatory protein H-NS. Nucleic Acids Res 2024; 52:2157-2173. [PMID: 38340344 PMCID: PMC10954469 DOI: 10.1093/nar/gkae090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 01/03/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024] Open
Abstract
Environmentally regulated gene expression is critical for bacterial survival under stress conditions, including extremes in temperature, osmolarity and nutrient availability. Here, we dissect the thermo- and osmo-responsory behavior of the transcriptional repressor H-NS, an archetypal nucleoid-condensing sensory protein, ubiquitous in enterobacteria that infect the mammalian gut. Through experiments and thermodynamic modeling, we show that H-NS exhibits osmolarity, temperature and concentration dependent self-association, with a highly polydisperse native ensemble dominated by monomers, dimers, tetramers and octamers. The relative population of these oligomeric states is determined by an interplay between dimerization and higher-order oligomerization, which in turn drives a competition between weak homo- versus hetero-oligomerization of protein-protein and protein-DNA complexes. A phosphomimetic mutation, Y61E, fully eliminates higher-order self-assembly and preserves only dimerization while weakening DNA binding, highlighting that oligomerization is a prerequisite for strong DNA binding. We further demonstrate the presence of long-distance thermodynamic connectivity between dimerization and oligomerization sites on H-NS which influences the binding of the co-repressor Cnu, and switches the DNA binding mode of the hetero-oligomeric H-NS:Cnu complex. Our work thus uncovers important organizational principles in H-NS including a multi-layered thermodynamic control, and provides a molecular framework broadly applicable to other thermo-osmo sensory proteins that employ similar mechanisms to regulate gene expression.
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Affiliation(s)
- Bincy Lukose
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | | | - Mohammed A Faidh
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | | | - Athi N Naganathan
- Department of Biotechnology, Bhupat & Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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3
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van Heesch T, Bolhuis PG, Vreede J. Decoding dissociation of sequence-specific protein-DNA complexes with non-equilibrium simulations. Nucleic Acids Res 2023; 51:12150-12160. [PMID: 37953329 PMCID: PMC10711434 DOI: 10.1093/nar/gkad1014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 10/13/2023] [Accepted: 10/19/2023] [Indexed: 11/14/2023] Open
Abstract
Sequence-specific protein-DNA interactions are crucial in processes such as DNA organization, gene regulation and DNA replication. Obtaining detailed insights into the recognition mechanisms of protein-DNA complexes through experiments is hampered by a lack of resolution in both space and time. Here, we present a molecular simulation approach to quantify the sequence specificity of protein-DNA complexes, that yields results fast, and is generally applicable to any protein-DNA complex. The approach is based on molecular dynamics simulations in combination with a sophisticated steering potential and results in an estimate of the free energy difference of dissociation. We provide predictions of the nucleotide specific binding affinity of the minor groove binding Histone-like Nucleoid Structuring (H-NS) protein, that are in agreement with experimental data. Furthermore, our approach offers mechanistic insight into the process of dissociation. Applying our approach to the major groove binding ETS domain in complex with three different nucleotide sequences identified the high affinity consensus sequence, quantitatively in agreement with experiments. Our protocol facilitates quantitative prediction of protein-DNA complex stability, while also providing high resolution insights into recognition mechanisms. As such, our simulation approach has the potential to yield detailed and quantitative insights into biological processes involving sequence-specific protein-DNA interactions.
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Affiliation(s)
- Thor van Heesch
- Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Netherlands
| | - Peter G Bolhuis
- Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Netherlands
| | - Jocelyne Vreede
- Van ’t Hoff Institute for Molecular Sciences, University of Amsterdam, Netherlands
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4
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Rashid FZM, Crémazy FGE, Hofmann A, Forrest D, Grainger DC, Heermann DW, Dame RT. The environmentally-regulated interplay between local three-dimensional chromatin organisation and transcription of proVWX in E. coli. Nat Commun 2023; 14:7478. [PMID: 37978176 PMCID: PMC10656529 DOI: 10.1038/s41467-023-43322-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 11/07/2023] [Indexed: 11/19/2023] Open
Abstract
Nucleoid associated proteins (NAPs) maintain the architecture of bacterial chromosomes and regulate gene expression. Thus, their role as transcription factors may involve three-dimensional chromosome re-organisation. While this model is supported by in vitro studies, direct in vivo evidence is lacking. Here, we use RT-qPCR and 3C-qPCR to study the transcriptional and architectural profiles of the H-NS (histone-like nucleoid structuring protein)-regulated, osmoresponsive proVWX operon of Escherichia coli at different osmolarities and provide in vivo evidence for transcription regulation by NAP-mediated chromosome re-modelling in bacteria. By consolidating our in vivo investigations with earlier in vitro and in silico studies that provide mechanistic details of how H-NS re-models DNA in response to osmolarity, we report that activation of proVWX in response to a hyperosmotic shock involves the destabilization of H-NS-mediated bridges anchored between the proVWX downstream and upstream regulatory elements (DRE and URE), and between the DRE and ygaY that lies immediately downstream of proVWX. The re-establishment of these bridges upon adaptation to hyperosmolarity represses the operon. Our results also reveal additional structural features associated with changes in proVWX transcript levels such as the decompaction of local chromatin upstream of the operon, highlighting that further complexity underlies the regulation of this model operon. H-NS and H-NS-like proteins are wide-spread amongst bacteria, suggesting that chromosome re-modelling may be a typical feature of transcriptional control in bacteria.
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Affiliation(s)
- Fatema-Zahra M Rashid
- Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333CC, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, 2333CC, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, 2333CC, The Netherlands
| | - Frédéric G E Crémazy
- Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333CC, The Netherlands
- Laboratoire Infection et Inflammation, INSERM, UVSQ, Université Paris-Saclay, Versailles, 78180, France
| | - Andreas Hofmann
- Statistical Physics and Theoretical Biophysics, Heidelberg University, Heidelberg, D-69120, Germany
| | - David Forrest
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - David C Grainger
- School of Biosciences, University of Birmingham, Edgbaston, B15 2TT, UK
| | - Dieter W Heermann
- Statistical Physics and Theoretical Biophysics, Heidelberg University, Heidelberg, D-69120, Germany
| | - Remus T Dame
- Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Leiden, 2333CC, The Netherlands.
- Centre for Microbial Cell Biology, Leiden University, Leiden, 2333CC, The Netherlands.
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, 2333CC, The Netherlands.
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5
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Gerson TM, Ott AM, Karney MMA, Socea JN, Ginete DR, Iyer LM, Aravind L, Gary RK, Wing HJ. VirB, a key transcriptional regulator of Shigella virulence, requires a CTP ligand for its regulatory activities. mBio 2023; 14:e0151923. [PMID: 37728345 PMCID: PMC10653881 DOI: 10.1128/mbio.01519-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 07/25/2023] [Indexed: 09/21/2023] Open
Abstract
IMPORTANCE Shigella species cause bacillary dysentery, the second leading cause of diarrheal deaths worldwide. There is a pressing need to identify novel molecular drug targets. Shigella virulence phenotypes are controlled by the transcriptional regulator, VirB. We show that VirB belongs to a fast-evolving, plasmid-borne clade of the ParB superfamily, which has diverged from versions with a distinct cellular role-DNA partitioning. We report that, like classic members of the ParB family, VirB binds a highly unusual ligand, CTP. Mutants predicted to be defective in CTP binding are compromised in a variety of virulence attributes controlled by VirB, likely because these mutants cannot engage DNA. This study (i) reveals that VirB binds CTP, (ii) provides a link between VirB-CTP interactions and Shigella virulence phenotypes, (iii) provides new insight into VirB-CTP-DNA interactions, and (iv) broadens our understanding of the ParB superfamily, a group of bacterial proteins that play critical roles in many bacteria.
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Affiliation(s)
- Taylor M. Gerson
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Audrey M. Ott
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Monika M. A. Karney
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Jillian N. Socea
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Daren R. Ginete
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | | | - L. Aravind
- Computational Biology Branch, National Library of Medicine, Bethesda, Maryland, USA
| | - Ronald K. Gary
- Department of Chemistry and Biochemistry, University of Nevada Las Vegas, Las Vegas, Nevada, USA
| | - Helen J. Wing
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, USA
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6
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Shmakov SA, Barth ZK, Makarova KS, Wolf Y, Brover V, Peters J, Koonin E. Widespread CRISPR-derived RNA regulatory elements in CRISPR-Cas systems. Nucleic Acids Res 2023; 51:8150-8168. [PMID: 37283088 PMCID: PMC10450183 DOI: 10.1093/nar/gkad495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/15/2023] [Accepted: 05/25/2023] [Indexed: 06/08/2023] Open
Abstract
CRISPR-cas loci typically contain CRISPR arrays with unique spacers separating direct repeats. Spacers along with portions of adjacent repeats are transcribed and processed into CRISPR(cr) RNAs that target complementary sequences (protospacers) in mobile genetic elements, resulting in cleavage of the target DNA or RNA. Additional, standalone repeats in some CRISPR-cas loci produce distinct cr-like RNAs implicated in regulatory or other functions. We developed a computational pipeline to systematically predict crRNA-like elements by scanning for standalone repeat sequences that are conserved in closely related CRISPR-cas loci. Numerous crRNA-like elements were detected in diverse CRISPR-Cas systems, mostly, of type I, but also subtype V-A. Standalone repeats often form mini-arrays containing two repeat-like sequence separated by a spacer that is partially complementary to promoter regions of cas genes, in particular cas8, or cargo genes located within CRISPR-Cas loci, such as toxins-antitoxins. We show experimentally that a mini-array from a type I-F1 CRISPR-Cas system functions as a regulatory guide. We also identified mini-arrays in bacteriophages that could abrogate CRISPR immunity by inhibiting effector expression. Thus, recruitment of CRISPR effectors for regulatory functions via spacers with partial complementarity to the target is a common feature of diverse CRISPR-Cas systems.
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Affiliation(s)
- Sergey A Shmakov
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Zachary K Barth
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Vyacheslav Brover
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Joseph E Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
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7
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Getz LJ, Brown JM, Sobot L, Chow A, Mahendrarajah J, Thomas N. Attenuation of a DNA cruciform by a conserved regulator directs T3SS1 mediated virulence in Vibrio parahaemolyticus. Nucleic Acids Res 2023; 51:6156-6171. [PMID: 37158250 PMCID: PMC10325908 DOI: 10.1093/nar/gkad370] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/23/2023] [Accepted: 04/27/2023] [Indexed: 05/10/2023] Open
Abstract
Pathogenic Vibrio species account for 3-5 million annual life-threatening human infections. Virulence is driven by bacterial hemolysin and toxin gene expression often positively regulated by the winged helix-turn-helix (wHTH) HlyU transcriptional regulator family and silenced by histone-like nucleoid structural protein (H-NS). In the case of Vibrio parahaemolyticus, HlyU is required for virulence gene expression associated with type 3 Secretion System-1 (T3SS1) although its mechanism of action is not understood. Here, we provide evidence for DNA cruciform attenuation mediated by HlyU binding to support concomitant virulence gene expression. Genetic and biochemical experiments revealed that upon HlyU mediated DNA cruciform attenuation, an intergenic cryptic promoter became accessible allowing for exsA mRNA expression and initiation of an ExsA autoactivation feedback loop at a separate ExsA-dependent promoter. Using a heterologous E. coli expression system, we reconstituted the dual promoter elements which revealed that HlyU binding and DNA cruciform attenuation were strictly required to initiate the ExsA autoactivation loop. The data indicate that HlyU acts to attenuate a transcriptional repressive DNA cruciform to support T3SS1 virulence gene expression and reveals a non-canonical extricating gene regulation mechanism in pathogenic Vibrio species.
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Affiliation(s)
- Landon J Getz
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
| | - Justin M Brown
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
| | - Lauren Sobot
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
| | - Alexandra Chow
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
| | - Jastina Mahendrarajah
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
| | - Nikhil A Thomas
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
- Department of Medicine, Faculty of Medicine, Dalhousie University. Halifax, NS, Canada
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8
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Rashid FZM, Dame RT. Three-dimensional chromosome re-modelling: The integral mechanism of transcription regulation in bacteria. Mol Microbiol 2023; 120:60-70. [PMID: 37433047 DOI: 10.1111/mmi.15062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 07/13/2023]
Abstract
Nucleoid-associated proteins (NAPs) are architectural proteins of the bacterial chromosome and transcription factors that dynamically organise the chromosome and regulate gene expression in response to physicochemical environmental signals. While the architectural and regulatory functions of NAPs have been verified independently, the coupling between these functions in vivo has not been conclusively proven. Here we describe a model NAP - histone-like nucleoid structuring protein (H-NS) - as a coupled sensor-effector that directly regulates gene expression by chromatin re-modelling in response to physicochemical environmental signals. We outline how H-NS-binding partners and post-translational modifications modulate the role of H-NS as a transcription factor by influencing its DNA structuring properties. We consolidate our ideas in models of how H-NS may regulate the expression of the proVWX and hlyCABD operons by chromatin re-modelling. The interplay between chromosome structure and gene expression may be a common - but, at present, under-appreciated - concept of transcription regulation in bacteria.
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Affiliation(s)
- Fatema-Zahra M Rashid
- Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands
| | - Remus T Dame
- Macromolecular Biochemistry, Leiden Institute of Chemistry, Leiden University, Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
- Centre for Interdisciplinary Genome Research, Leiden University, Leiden, The Netherlands
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9
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Gerson TM, Ott AM, Karney MMA, Socea JN, Ginete DR, Iyer LM, Aravind L, Gary RK, Wing HJ. VirB, a key transcriptional regulator of Shigella virulence, requires a CTP ligand for its regulatory activities. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.16.541010. [PMID: 37293012 PMCID: PMC10245682 DOI: 10.1101/2023.05.16.541010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The VirB protein, encoded by the large virulence plasmid of Shigella spp., is a key transcriptional regulator of virulence genes. Without a functional virB gene, Shigella cells are avirulent. On the virulence plasmid, VirB functions to offset transcriptional silencing mediated by the nucleoid structuring protein, H-NS, which binds and sequesters AT-rich DNA, making it inaccessible for gene expression. Thus, gaining a mechanistic understanding of how VirB counters H-NS-mediated silencing is of considerable interest. VirB is unusual in that it does not resemble classic transcription factors. Instead, its closest relatives are found in the ParB superfamily, where the best-characterized members function in faithful DNA segregation before cell division. Here, we show that VirB is a fast-evolving member of this superfamily and report for the first time that the VirB protein binds a highly unusual ligand, CTP. VirB binds this nucleoside triphosphate preferentially and with specificity. Based on alignments with the best-characterized members of the ParB family, we identify amino acids of VirB likely to bind CTP. Substitutions in these residues disrupt several well-documented activities of VirB, including its anti-silencing activity at a VirB-dependent promoter, its role in generating a Congo red positive phenotype in Shigella , and the ability of the VirB protein to form foci in the bacterial cytoplasm when fused to GFP. Thus, this work is the first to show that VirB is a bona fide CTP-binding protein and links Shigella virulence phenotypes to the nucleoside triphosphate, CTP. Importance Shigella species cause bacillary dysentery (shigellosis), the second leading cause of diarrheal deaths worldwide. With growing antibiotic resistance, there is a pressing need to identify novel molecular drug targets. Shigella virulence phenotypes are controlled by the transcriptional regulator, VirB. We show that VirB belongs to a fast-evolving, primarily plasmid-borne clade of the ParB superfamily, which has diverged from versions that have a distinct cellular role - DNA partitioning. We are the first to report that, like classic members of the ParB family, VirB binds a highly unusual ligand, CTP. Mutants predicted to be defective in CTP binding are compromised in a variety of virulence attributes controlled by VirB. This study i) reveals that VirB binds CTP, ii) provides a link between VirB-CTP interactions and Shigella virulence phenotypes, and iii) broadens our understanding of the ParB superfamily, a group of bacterial proteins that play critical roles in many different bacteria.
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Affiliation(s)
- Taylor M. Gerson
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Audrey M. Ott
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Monika MA. Karney
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Jillian N. Socea
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Daren R. Ginete
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Lakshminarayan M. Iyer
- Computational Biology Branch, 8600 Rockville Pike, Building 38A, Room 5N505, National Library of Medicine, Bethesda, MD 20894
| | - L. Aravind
- Computational Biology Branch, 8600 Rockville Pike, Building 38A, Room 5N505, National Library of Medicine, Bethesda, MD 20894
| | - Ronald K. Gary
- Department of Chemistry and Biochemistry, University of Nevada Las Vegas, Las Vegas, NV 89154-4003
| | - Helen J. Wing
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
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10
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Picker MA, Karney MMA, Gerson TM, Karabachev A, Duhart J, McKenna J, Wing H. Localized modulation of DNA supercoiling, triggered by the Shigella anti-silencer VirB, is sufficient to relieve H-NS-mediated silencing. Nucleic Acids Res 2023; 51:3679-3695. [PMID: 36794722 PMCID: PMC10164555 DOI: 10.1093/nar/gkad088] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 01/27/2023] [Accepted: 01/31/2023] [Indexed: 02/17/2023] Open
Abstract
In Bacteria, nucleoid structuring proteins govern nucleoid dynamics and regulate transcription. In Shigella spp., at ≤30°C, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences many genes on the large virulence plasmid. Upon a switch to 37°C, VirB, a DNA binding protein and key transcriptional regulator of Shigella virulence, is produced. VirB functions to counter H-NS-mediated silencing in a process called transcriptional anti-silencing. Here, we show that VirB mediates a loss of negative DNA supercoils from our plasmid-borne, VirB-regulated PicsP-lacZ reporter in vivo. The changes are not caused by a VirB-dependent increase in transcription, nor do they require the presence of H-NS. Instead, the VirB-dependent change in DNA supercoiling requires the interaction of VirB with its DNA binding site, a critical first step in VirB-dependent gene regulation. Using two complementary approaches, we show that VirB:DNA interactions in vitro introduce positive supercoils in plasmid DNA. Subsequently, by exploiting transcription-coupled DNA supercoiling, we reveal that a localized loss of negative supercoils is sufficient to alleviate H-NS-mediated transcriptional silencing independently of VirB. Together, our findings provide novel insight into VirB, a central regulator of Shigella virulence and, more broadly, a molecular mechanism that offsets H-NS-dependent silencing of transcription in bacteria.
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Affiliation(s)
- Michael A Picker
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Monika M A Karney
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Taylor M Gerson
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | | | - Juan C Duhart
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Joy A McKenna
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Helen J Wing
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154-4004, USA
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11
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Shmakov SA, Barth ZK, Makarova KS, Wolf YI, Brover V, Peters JE, Koonin EV. Widespread CRISPR repeat-like RNA regulatory elements in CRISPR-Cas systems. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.03.530964. [PMID: 37090614 PMCID: PMC10120712 DOI: 10.1101/2023.03.03.530964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
CRISPR- cas loci typically contain CRISPR arrays with unique spacers separating direct repeats. Spacers along with portions of adjacent repeats are transcribed and processed into CRISPR(cr) RNAs that target complementary sequences (protospacers) in mobile genetic elements, resulting in cleavage of the target DNA or RNA. Additional, standalone repeats in some CRISPR- cas loci produce distinct cr-like RNAs implicated in regulatory or other functions. We developed a computational pipeline to systematically predict crRNA-like elements by scanning for standalone repeat sequences that are conserved in closely related CRISPR- cas loci. Numerous crRNA-like elements were detected in diverse CRISPR-Cas systems, mostly, of type I, but also subtype V-A. Standalone repeats often form mini-arrays containing two repeat-like sequence separated by a spacer that is partially complementary to promoter regions of cas genes, in particular cas8 , or cargo genes located within CRISPR-Cas loci, such as toxins-antitoxins. We show experimentally that a mini-array from a type I-F1 CRISPR-Cas system functions as a regulatory guide. We also identified mini-arrays in bacteriophages that could abrogate CRISPR immunity by inhibiting effector expression. Thus, recruitment of CRISPR effectors for regulatory functions via spacers with partial complementarity to the target is a common feature of diverse CRISPR-Cas systems.
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Affiliation(s)
- Sergey A. Shmakov
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Zachary K. Barth
- Department of Microbiology, Cornell University, Ithaca, NY 14853
| | - Kira S. Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Yuri I. Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Vyacheslav Brover
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
| | - Joseph E. Peters
- Department of Microbiology, Cornell University, Ithaca, NY 14853
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA
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12
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Han Y, Li J, Gao H, Li X, Duan R, Cheng Q, Kan B, Liang W. Serotype conversion gene rfbT is directly regulated by histone-like nucleoid structuring protein (H-NS) in V. cholerae O1. Front Microbiol 2023; 14:1111895. [PMID: 36819035 PMCID: PMC9929944 DOI: 10.3389/fmicb.2023.1111895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
Vibrio cholerae serogroup O1 (V. cholerae O1) is closely associated with cholera epidemics and has two main immunologically distinguishable serotypes, Ogawa and Inaba. Isolates serotype as Ogawa if the O-antigen polysaccharide (O-PS) is methylated or as Inaba if the O-PS is not methylated. This methylation is mediated by a methyltransferase encoded by the rfbT gene, and the mutation and low expression of rfbT results in serotype switch from Ogawa to Inaba. Previously, we have shown that cAMP receptor protein (CRP) activates rfbT. In this study, we demonstrated that histone-like nucleoid structuring protein (H-NS) is directly involved in the transcriptional repression of rfbT. This finding is supported by the analyses of rfbT mRNA level, rfbT-lux reporter fusions, electrophoretic mobility shift assay (EMSA), and DNase I footprinting assay. The rfbT mRNA abundances were significantly increased by deleting hns rather than fis which also preferentially associates with AT-rich sequences. A single-copy chromosomal complement of hns partly restored the down-regulation of rfbT. Analysis of rfbT-lux reporter fusions validated the transcriptional repression of hns. Subsequent EMSA and DNase I footprinting assay confirmed the direct binding of H-NS to rfbT promoter and mapped the exact binding site which was further verified by site-directed mutagenesis and promoter functional analysis. Furthermore, we found that in hns deletion mutant, CRP is no longer required for transcriptionally activating rfbT, suggesting that CRP functions as a dedicated transcription factor to relieve H-NS repression at rfbT. Together, this study expanded our understanding of the genetic regulatory mechanism of serotype conversion by global regulators in V. cholerae O1.
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Affiliation(s)
| | | | | | | | | | | | - Biao Kan
- *Correspondence: Weili Liang, ; Biao Kan,
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13
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Picker MA, Karney MMA, Gerson TM, Karabachev AD, Duhart JC, McKenna JA, Wing HJ. Localized modulation of DNA supercoiling, triggered by the Shigella anti-silencer VirB, is sufficient to relieve H-NS-mediated silencing. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.09.523335. [PMID: 36711906 PMCID: PMC9882051 DOI: 10.1101/2023.01.09.523335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In Bacteria, nucleoid structuring proteins govern nucleoid dynamics and regulate transcription. In Shigella spp ., at ≤ 30 °C, the histone-like nucleoid structuring protein (H-NS) transcriptionally silences many genes on the large virulence plasmid. Upon a switch to 37 °C, VirB, a DNA binding protein and key transcriptional regulator of Shigella virulence, is produced. VirB functions to counter H-NS-mediated silencing in a process called transcriptional anti-silencing. Here, we show that VirB mediates a loss of negative DNA supercoils from our plasmid-borne, VirB-regulated PicsP-lacZ reporter, in vivo . The changes are not caused by a VirB-dependent increase in transcription, nor do they require the presence of H-NS. Instead, the VirB-dependent change in DNA supercoiling requires the interaction of VirB with its DNA binding site, a critical first step in VirB-dependent gene regulation. Using two complementary approaches, we show that VirB:DNA interactions in vitro introduce positive supercoils in plasmid DNA. Subsequently, by exploiting transcription-coupled DNA supercoiling, we reveal that a localized loss of negative supercoils is sufficient to alleviate H-NS-mediated transcriptional silencing, independently of VirB. Together, our findings provide novel insight into VirB, a central regulator of Shigella virulence and more broadly, a molecular mechanism that offsets H-NS-dependent silencing of transcription in bacteria.
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14
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Pervasive transcription enhances the accessibility of H-NS-silenced promoters and generates bistability in Salmonella virulence gene expression. Proc Natl Acad Sci U S A 2022; 119:e2203011119. [PMID: 35858437 PMCID: PMC9335307 DOI: 10.1073/pnas.2203011119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
In Escherichia coli and Salmonella, many genes silenced by the nucleoid structuring protein H-NS are activated upon inhibiting Rho-dependent transcription termination. This response is poorly understood and difficult to reconcile with the view that H-NS acts mainly by blocking transcription initiation. Here we have analyzed the basis for the up-regulation of H-NS-silenced Salmonella pathogenicity island 1 (SPI-1) in cells depleted of Rho-cofactor NusG. Evidence from genetic experiments, semiquantitative 5' rapid amplification of complementary DNA ends sequencing (5' RACE-Seq), and chromatin immunoprecipitation sequencing (ChIP-Seq) shows that transcription originating from spurious antisense promoters, when not stopped by Rho, elongates into a H-NS-bound regulatory region of SPI-1, displacing H-NS and rendering the DNA accessible to the master regulator HilD. In turn, HilD's ability to activate its own transcription triggers a positive feedback loop that results in transcriptional activation of the entire SPI-1. Significantly, single-cell analyses revealed that this mechanism is largely responsible for the coexistence of two subpopulations of cells that either express or do not express SPI-1 genes. We propose that cell-to-cell differences produced by stochastic spurious transcription, combined with feedback loops that perpetuate the activated state, can generate bimodal gene expression patterns in bacterial populations.
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15
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Bacterial H-NS contacts DNA at the same irregularly spaced sites in both bridged and hemi-sequestered linear filaments. iScience 2022; 25:104429. [PMID: 35669520 PMCID: PMC9162952 DOI: 10.1016/j.isci.2022.104429] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/01/2022] [Accepted: 05/13/2022] [Indexed: 11/22/2022] Open
Abstract
Gene silencing in bacteria is mediated by chromatin proteins, of which Escherichia coli H-NS is a paradigmatic example. H-NS forms nucleoprotein filaments with either one or two DNA duplexes. However, the structures, arrangements of DNA-binding domains (DBDs), and positions of DBD-DNA contacts in linear and bridged filaments are uncertain. To characterize the H-NS DBD contacts that silence transcription by RNA polymerase, we combined ·OH footprinting, molecular dynamics, statistical modeling, and DBD mapping using a chemical nuclease (Fe2+-EDTA) tethered to the DBDs (TEN-map). We find that H-NS DBDs contact DNA at indistinguishable locations in bridged or linear filaments and that the DBDs vary in orientation and position with ∼10-bp average spacing. Our results support a hemi-sequestration model of linear-to-bridged H-NS switching. Linear filaments able to inhibit only transcription initiation switch to bridged filaments able to inhibit both initiation and elongation using the same irregularly spaced DNA contacts.
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16
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The AraC/XylS Protein MxiE and Its Coregulator IpgC Control a Negative Feedback Loop in the Transcriptional Cascade That Regulates Type III Secretion in Shigella flexneri. J Bacteriol 2022; 204:e0013722. [PMID: 35703565 DOI: 10.1128/jb.00137-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Members of the AraC family of transcriptional regulators (AFTRs) control the expression of many genes important to cellular processes, including virulence. In Shigella species, the type III secretion system (T3SS), a key determinant for host cell invasion, is regulated by the three-tiered VirF/VirB/MxiE transcriptional cascade. Both VirF and MxiE belong to the AFTRs and are characterized as positive transcriptional regulators. Here, we identify a novel regulatory activity for MxiE and its coregulator IpgC, which manifests as a negative feedback loop in the VirF/VirB/MxiE transcriptional cascade. Our findings show that MxiE and IpgC downregulate the virB promoter and, hence, VirB protein production, thus decreasing VirB-dependent promoter activity at ospD1, one of the nearly 50 VirB-dependent genes. At the virB promoter, regions required for negative MxiE- and IpgC-dependent regulation were mapped and found to be coincident with regions required for positive VirF-dependent regulation. In tandem, negative MxiE- and IpgC-dependent regulation of the virB promoter only occurred in the presence of VirF, suggesting that MxiE and IpgC can function to counter VirF activation of the virB promoter. Lastly, MxiE and IpgC do not downregulate another VirF-activated promoter, icsA, demonstrating that this negative feedback loop targets the virB promoter. Our study provides insight into a mechanism that may reprogram Shigella virulence gene expression following type III secretion and provides the impetus to examine if MxiE and IpgC homologs in other important bacterial pathogens, such as Burkholderia pseudomallei and Salmonella enterica serovars Typhimurium and Typhi, coordinate similar negative feedback loops. IMPORTANCE The large AraC family of transcriptional regulators (AFTRs) control virulence gene expression in many bacterial pathogens. In Shigella species, the AraC/XylS protein MxiE and its coregulator IpgC positively regulate the expression of type III secretion system genes within the three-tiered VirF/VirB/MxiE transcriptional cascade. Our findings suggest a negative feedback loop in the VirF/VirB/MxiE cascade, in which MxiE and IpgC counter VirF-dependent activation of the virB promoter, thus making this the first characterization of negative MxiE- and IpgC-dependent regulation. Our study provides insight into a mechanism that likely reprograms Shigella virulence gene expression following type III secretion, which has implications for other important bacterial pathogens with functional homologs of MxiE and IpgC.
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Relationship between the Chromosome Structural Dynamics and Gene Expression—A Chicken and Egg Dilemma? Microorganisms 2022; 10:microorganisms10050846. [PMID: 35630292 PMCID: PMC9144111 DOI: 10.3390/microorganisms10050846] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 04/14/2022] [Indexed: 02/06/2023] Open
Abstract
Prokaryotic transcription was extensively studied over the last half-century. A great deal of data has been accumulated regarding the control of gene expression by transcription factors regulating their target genes by binding at specific DNA sites. However, there is a significant gap between the mechanistic description of transcriptional control obtained from in vitro biochemical studies and the complexity of transcriptional regulation in the context of the living cell. Indeed, recent studies provide ample evidence for additional levels of complexity pertaining to the regulation of transcription in vivo, such as, for example, the role of the subcellular localization and spatial organization of different molecular components involved in the transcriptional control and, especially, the role of chromosome configurational dynamics. The question as to how the chromosome is dynamically reorganized under the changing environmental conditions and how this reorganization is related to gene expression is still far from being clear. In this article, we focus on the relationships between the chromosome structural dynamics and modulation of gene expression during bacterial adaptation. We argue that spatial organization of the bacterial chromosome is of central importance in the adaptation of gene expression to changing environmental conditions and vice versa, that gene expression affects chromosome dynamics.
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Global Chromosome Topology and the Two-Component Systems in Concerted Manner Regulate Transcription in Streptomyces. mSystems 2021; 6:e0114221. [PMID: 34783581 PMCID: PMC8594442 DOI: 10.1128/msystems.01142-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Bacterial gene expression is controlled at multiple levels, with chromosome supercoiling being one of the most global regulators. Global DNA supercoiling is maintained by the orchestrated action of topoisomerases. In Streptomyces, mycelial soil bacteria with a complex life cycle, topoisomerase I depletion led to elevated chromosome supercoiling, changed expression of a significant fraction of genes, delayed growth, and blocked sporulation. To identify supercoiling-induced sporulation regulators, we searched for Streptomyces coelicolor transposon mutants that were able to restore sporulation despite high chromosome supercoiling. We established that transposon insertion in genes encoding a novel two-component system named SatKR reversed the sporulation blockage resulting from topoisomerase I depletion. Transposition in satKR abolished the transcriptional induction of the genes within the so-called supercoiling-hypersensitive cluster (SHC). Moreover, we found that activated SatR also induced the same set of SHC genes under normal supercoiling conditions. We determined that the expression of genes in this region impacted S. coelicolor growth and sporulation. Interestingly, among the associated products is another two-component system (SitKR), indicating the potential for cascading regulatory effects driven by the SatKR and SitKR two-component systems. Thus, we demonstrated the concerted activity of chromosome supercoiling and a hierarchical two-component signaling system that impacts gene activity governing Streptomyces growth and sporulation. IMPORTANCEStreptomyces microbes, soil bacteria with complex life cycle, are the producers of a broad range of biologically active compounds (e.g., antibiotics). Streptomyces bacteria respond to various environmental signals using a complex transcriptional regulation mechanism. Understanding regulation of their gene expression is crucial for Streptomyces application as industrial organisms. Here, on the basis of the results of extensive transcriptomics analyses, we describe the concerted gene regulation by global DNA supercoiling and novel two-component system. Our data indicate that regulated genes encode growth and sporulation regulators. Thus, we demonstrate that Streptomyces bacteria link the global regulatory strategies to adjust life cycle to unfavorable conditions.
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Long-Distance Effects of H-NS Binding in the Control of hilD Expression in the Salmonella SPI1 Locus. J Bacteriol 2021; 203:e0030821. [PMID: 34424033 DOI: 10.1128/jb.00308-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhimurium utilizes a type three secretion system (T3SS) carried on the Salmonella pathogenicity island 1 (SPI1) to invade intestinal epithelial cells and induce inflammatory diarrhea. HilA activates expression of the T3SS structural genes. Expression of hyper invasion locus A (hilA) is controlled by the transcription factors HilD, HilC, and RtsA, which act in a complex feed-forward regulatory loop. The nucleoid-associated protein H-NS is a xenogeneic silencer that has a major effect on SPI1 expression. In this work, we use genetic techniques to show that disruptions of the chromosomal region surrounding hilD have a cis effect on H-NS-mediated repression of the hilD promoter; this effect occurs asymmetrically over ∼4 kb spanning the prgH-hilD intergenic region. CAT cassettes inserted at various positions in this region are also silenced in relation to the proximity to the hilD promoter. We identify a putative H-NS nucleation site, and its mutation results in derepression of the locus. Furthermore, we genetically show that HilD abrogates H-NS-mediated silencing to activate the hilD promoter. In contrast, H-NS-mediated repression of the hilA promoter, downstream of hilD, is through its control of HilD, which directly activates hilA transcription. Likewise, activation of the prgH promoter, although in a region silenced by H-NS, is strictly dependent on HilA. In summary, we propose a model in which H-NS nucleates within the hilD promoter region to polymerize and exert its repressive effect. Thus, H-NS-mediated repression of SPI1 is primarily through the control of hilD expression, with HilD capable of overcoming H-NS to autoactivate. IMPORTANCE Members of the foodborne pathogen Salmonella rely on a type III secretion system to invade intestinal epithelial cells and initiate infection. This system was acquired through horizontal gene transfer, essentially creating the Salmonella genus. Expression of this critical virulence factor is controlled by a complex regulatory network. The nucleoid protein H-NS is a global repressor of horizontally acquired genomic loci. Here, we identify the critical site of H-NS regulation in this system and show that alterations to the DNA over a surprisingly large region affect this regulation, providing important information regarding the mechanism of H-NS action.
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Böhme K, Heroven AK, Lobedann S, Guo Y, Stolle AS, Dersch P. The Small Protein YmoA Controls the Csr System and Adjusts Expression of Virulence-Relevant Traits of Yersinia pseudotuberculosis. Front Microbiol 2021; 12:706934. [PMID: 34413840 PMCID: PMC8369931 DOI: 10.3389/fmicb.2021.706934] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 07/12/2021] [Indexed: 11/24/2022] Open
Abstract
Virulence gene expression of Yersinia pseudotuberculosis changes during the different stages of infection and this is tightly controlled by environmental cues. In this study, we show that the small protein YmoA, a member of the Hha family, is part of this process. It controls temperature- and nutrient-dependent early and later stage virulence genes in an opposing manner and co-regulates bacterial stress responses and metabolic functions. Our analysis further revealed that YmoA exerts this function by modulating the global post-transcriptional regulatory Csr system. YmoA pre-dominantly enhances the stability of the regulatory RNA CsrC. This involves a stabilizing stem-loop structure within the 5′-region of CsrC. YmoA-mediated CsrC stabilization depends on H-NS, but not on the RNA chaperone Hfq. YmoA-promoted reprogramming of the Csr system has severe consequences for the cell: we found that a mutant deficient of ymoA is strongly reduced in its ability to enter host cells and to disseminate to the Peyer’s patches, mesenteric lymph nodes, liver and spleen in mice. We propose a model in which YmoA controls transition from the initial colonization phase in the intestine toward the host defense phase important for the long-term establishment of the infection in underlying tissues.
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Affiliation(s)
- Katja Böhme
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Ann Kathrin Heroven
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stephanie Lobedann
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Yuzhu Guo
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
| | - Anne-Sophie Stolle
- Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
| | - Petra Dersch
- Department of Molecular Infection Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany.,Institute of Infectiology, Center for Molecular Biology of Inflammation (ZMBE), Medical Faculty Münster, University of Münster, Münster, Germany
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21
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H-NS and ToxT Inversely Control Cholera Toxin Production by Binding to Overlapping DNA Sequences. J Bacteriol 2021; 203:e0018721. [PMID: 34228499 DOI: 10.1128/jb.00187-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae infects human hosts following ingestion of contaminated food or water, resulting in the severe diarrheal disease cholera. The watery diarrhea that is characteristic of the disease is directly caused by the production of cholera toxin (CT). A complex regulatory cascade controls the production of CT and other virulence factors. However, ultimately, a single protein, ToxT, directly binds to virulence gene promoters and activates their transcription. Previously, we identified two ToxT binding sites, or toxboxes, within the cholera toxin promoter (PctxAB). The toxboxes overlap the two promoter-proximal GATTTTT heptad repeats found within PctxAB in classical biotype V. cholerae strain O395. These heptad repeats were previously found to be located within a large DNA region bound by H-NS, a global transcriptional repressor present in Gram-negative bacteria. The current model for the control of PctxAB transcription proposes complete H-NS displacement from the DNA by ToxT, followed by direct activation by ToxT-RNA polymerase (RNAP) contacts. The goal of this study was to determine more precisely where H-NS binds to PctxAB and test the hypothesis that ToxT completely displaces H-NS from the PctxAB promoter before activating transcription. The results suggest that H-NS binds only to the region of PctxAB encompassing the heptad repeats and that ToxT displaces H-NS only from its most promoter-proximal binding sites, calling for a revision of the current model involving H-NS and ToxT at PctxAB. IMPORTANCE H-NS is a global negative regulator of transcription in Gram-negative bacteria, particularly in horizontally acquired genetic islands. Previous work in Vibrio cholerae suggested that H-NS represses the transcription of cholera toxin genes by binding to a large region upstream of its promoter and that the virulence activator ToxT derepresses transcription by removing H-NS from the promoter. Here, new data support a revised model in which ToxT displaces only H-NS bound to the most promoter-proximal DNA sites that overlap the ToxT binding sites, leaving the upstream sites occupied by H-NS. This introduces a higher-resolution mechanism for the antirepression of H-NS in the control of cholera toxin production.
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Abstract
Since the nucleoid was isolated from bacteria in the 1970s, two fundamental questions emerged and are still in the spotlight: how bacteria organize their chromosomes to fit inside the cell and how nucleoid organization enables essential biological processes. During the last decades, knowledge of bacterial chromosome organization has advanced considerably, and today, such chromosomes are considered to be highly organized and dynamic structures that are shaped by multiple factors in a multiscale manner. Here we review not only the classical well-known factors involved in chromosome organization but also novel components that have recently been shown to dynamically shape the 3D structuring of the bacterial genome. We focus on the different functional elements that control short-range organization and describe how they collaborate in the establishment of the higher-order folding and disposition of the chromosome. Recent advances have opened new avenues for a deeper understanding of the principles and mechanisms of chromosome organization in bacteria. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Virginia S Lioy
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France;
| | - Ivan Junier
- Université Grenoble Alpes, CNRS, TIMC-IMAG, 38000 Grenoble, France
| | - Frédéric Boccard
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France;
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Ishihama A, Shimada T. Hierarchy of transcription factor network in Escherichia coli K-12: H-NS-mediated silencing and Anti-silencing by global regulators. FEMS Microbiol Rev 2021; 45:6312496. [PMID: 34196371 DOI: 10.1093/femsre/fuab032] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/15/2021] [Indexed: 12/13/2022] Open
Abstract
Transcriptional regulation for genome expression determines growth and adaptation of single-cell bacteria that are directly exposed to environment. The transcriptional apparatus in Escherichia coli K-12 is composed of RNA polymerase core enzyme and two groups of its regulatory proteins, seven species of promoter-recognition subunit sigma and about 300 species of transcription factors. The identification of regulatory targets for all these regulatory proteins is critical toward understanding the genome regulation as a whole. For this purpose, we performed a systematic search in vitro of the whole set of binding sites for each factor by gSELEX system. This review summarizes the accumulated knowledge of regulatory targets for more than 150 TFs from E. coli K-12. Overall TFs could be classified into four families: nucleoid-associated bifunctional TFs; global regulators; local regulators; and single-target regulators, in which the regulatory functions remain uncharacterized for the nucleoid-associated TFs. Here we overview the regulatory targets of two nucleoid-associated TFs, H-NS and its paralog StpA, both together playing the silencing role of a set of non-essential genes. Participation of LeuO and other global regulators have been indicated for the anti-silencing. Finally, we propose the hierarchy of TF network as a key framework of the bacterial genome regulation.
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Affiliation(s)
- Akira Ishihama
- Hosei University, Research Institute for Micro-Nano Technology, Koganei, Tokyo 184-0003, Japan
| | - Tomohiro Shimada
- Meiji University, School of Agriculture, Kawasaki, Kanagawa 214-8571, Japan
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Wójcicki M, Świder O, Daniluk KJ, Średnicka P, Akimowicz M, Roszko MŁ, Sokołowska B, Juszczuk-Kubiak E. Transcriptional Regulation of the Multiple Resistance Mechanisms in Salmonella-A Review. Pathogens 2021; 10:pathogens10070801. [PMID: 34202800 PMCID: PMC8308502 DOI: 10.3390/pathogens10070801] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 02/07/2023] Open
Abstract
The widespread use of antibiotics, especially those with a broad spectrum of activity, has resulted in the development of multidrug resistance in many strains of bacteria, including Salmonella. Salmonella is among the most prevalent causes of intoxication due to the consumption of contaminated food and water. Salmonellosis caused by this pathogen is pharmacologically treated using antibiotics such as fluoroquinolones, ceftriaxone, and azithromycin. This foodborne pathogen developed several molecular mechanisms of resistance both on the level of global and local transcription modulators. The increasing rate of antibiotic resistance in Salmonella poses a significant global concern, and an improved understanding of the multidrug resistance mechanisms in Salmonella is essential for choosing the suitable antibiotic for the treatment of infections. In this review, we summarized the current knowledge of molecular mechanisms that control gene expression related to antibiotic resistance of Salmonella strains. We characterized regulators acting as transcription activators and repressors, as well as two-component signal transduction systems. We also discuss the background of the molecular mechanisms of the resistance to metals, regulators of multidrug resistance to antibiotics, global regulators of the LysR family, as well as regulators of histone-like proteins.
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Affiliation(s)
- Michał Wójcicki
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Olga Świder
- Department of Food Safety and Chemical Analysis, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (O.Ś.); (M.Ł.R.)
| | - Kamila J. Daniluk
- Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (K.J.D.); (B.S.)
| | - Paulina Średnicka
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Monika Akimowicz
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
| | - Marek Ł. Roszko
- Department of Food Safety and Chemical Analysis, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (O.Ś.); (M.Ł.R.)
| | - Barbara Sokołowska
- Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (K.J.D.); (B.S.)
| | - Edyta Juszczuk-Kubiak
- Laboratory of Biotechnology and Molecular Engineering, Department of Microbiology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology—State Research Institute, Rakowiecka 36 Street, 02-532 Warsaw, Poland; (M.W.); (P.Ś.); (M.A.)
- Correspondence: ; Tel.: +48-22-6063605
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Duan B, Ding P, Navarre WW, Liu J, Xia B. Xenogeneic Silencing and Bacterial Genome Evolution: Mechanisms for DNA Recognition Imply Multifaceted Roles of Xenogeneic Silencers. Mol Biol Evol 2021; 38:4135-4148. [PMID: 34003286 PMCID: PMC8476142 DOI: 10.1093/molbev/msab136] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/08/2021] [Indexed: 12/14/2022] Open
Abstract
Horizontal gene transfer (HGT) is a major driving force for bacterial evolution. To avoid the deleterious effects due to the unregulated expression of newly acquired foreign genes, bacteria have evolved specific proteins named xenogeneic silencers to recognize foreign DNA sequences and suppress their transcription. As there is considerable diversity in genomic base compositions among bacteria, how xenogeneic silencers distinguish self- from nonself DNA in different bacteria remains poorly understood. This review summarizes the progress in studying the DNA binding preferences and the underlying molecular mechanisms of known xenogeneic silencer families, represented by H-NS of Escherichia coli, Lsr2 of Mycobacterium, MvaT of Pseudomonas, and Rok of Bacillus. Comparative analyses of the published data indicate that the differences in DNA recognition mechanisms enable these xenogeneic silencers to have clear characteristics in DNA sequence preferences, which are further correlated with different host genomic features. These correlations provide insights into the mechanisms of how these xenogeneic silencers selectively target foreign DNA in different genomic backgrounds. Furthermore, it is revealed that the genomic AT contents of bacterial species with the same xenogeneic silencer family proteins are distributed in a limited range and are generally lower than those species without any known xenogeneic silencers in the same phylum/class/genus, indicating that xenogeneic silencers have multifaceted roles on bacterial genome evolution. In addition to regulating horizontal gene transfer, xenogeneic silencers also act as a selective force against the GC to AT mutational bias found in bacterial genomes and help the host genomic AT contents maintained at relatively low levels.
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Affiliation(s)
- Bo Duan
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - Pengfei Ding
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
| | - William Wiley Navarre
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Jun Liu
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, M5G 1M1, Canada
| | - Bin Xia
- Beijing Nuclear Magnetic Resonance Center, College of Chemistry and Molecular Engineering, and School of Life Sciences, Peking University, Beijing, 100871, China
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Liu X, Lin S, Liu T, Zhou Y, Wang W, Yao J, Guo Y, Tang K, Chen R, Benedik MJ, Wang X. Xenogeneic silencing relies on temperature-dependent phosphorylation of the host H-NS protein in Shewanella. Nucleic Acids Res 2021; 49:3427-3440. [PMID: 33693785 PMCID: PMC8034616 DOI: 10.1093/nar/gkab137] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/17/2021] [Accepted: 02/20/2021] [Indexed: 12/20/2022] Open
Abstract
Lateral gene transfer (LGT) plays a key role in shaping the genome evolution and environmental adaptation of bacteria. Xenogeneic silencing is crucial to ensure the safe acquisition of LGT genes into host pre-existing regulatory networks. We previously found that the host nucleoid structuring protein (H-NS) silences prophage CP4So at warm temperatures yet enables this prophage to excise at cold temperatures in Shewanella oneidensis. However, whether H-NS silences other genes and how bacteria modulate H-NS to regulate the expression of genes have not been fully elucidated. In this study, we discovered that the H-NS silences many LGT genes and the xenogeneic silencing of H-NS relies on a temperature-dependent phosphorylation at warm temperatures in S. oneidensis. Specifically, phosphorylation of H-NS at Ser42 is critical for silencing the cold-inducible genes including the excisionase of CP4So prophage, a cold shock protein, and a stress-related chemosensory system. By contrast, nonphosphorylated H-NS derepresses the promoter activity of these genes/operons to enable their expression at cold temperatures. Taken together, our results reveal that the posttranslational modification of H-NS can function as a regulatory switch to control LGT gene expression in host genomes to enable the host bacterium to react and thrive when environmental temperature changes.
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Affiliation(s)
- Xiaoxiao Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China
| | - Shituan Lin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tianlang Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yiqing Zhou
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weiquan Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jianyun Yao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China
| | - Yunxue Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kaihao Tang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China
| | - Ran Chen
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China
| | - Michael J Benedik
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No.1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing 100049, China
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Japaridze A, Yang W, Dekker C, Nasser W, Muskhelishvili G. DNA sequence-directed cooperation between nucleoid-associated proteins. iScience 2021; 24:102408. [PMID: 33997690 PMCID: PMC8099737 DOI: 10.1016/j.isci.2021.102408] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/05/2021] [Accepted: 04/06/2021] [Indexed: 02/01/2023] Open
Abstract
Nucleoid-associated proteins (NAPs) are a class of highly abundant DNA-binding proteins in bacteria and archaea. While both the composition and relative abundance of the NAPs change during the bacterial growth cycle, surprisingly little is known about their crosstalk in mutually binding and stabilizing higher-order nucleoprotein complexes in the bacterial chromosome. Here, we use atomic force microscopy and solid-state nanopores to investigate long-range nucleoprotein structures formed by the binding of two major NAPs, FIS and H-NS, to DNA molecules with distinct binding site arrangements. We find that spatial organization of the protein binding sites can govern the higher-order architecture of the nucleoprotein complexes. Based on sequence arrangement the complexes differed in their global shape and compaction as well as the extent of FIS and H-NS binding. Our observations highlight the important role the DNA sequence plays in driving structural differentiation within the bacterial chromosome. The location of protein binding sites along DNA is important for 3D organization FIS protein forms DNA loops while H-NS forms compact DNA plectonemes FIS DNA loops inhibit H-NS from spreading over the DNA FIS and H-NS competition creates regions of ‘open’ and ‘closed’ DNA
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Affiliation(s)
- Aleksandre Japaridze
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Wayne Yang
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Cees Dekker
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - William Nasser
- Université de Lyon, INSA Lyon, Université Claude Bernard Lyon 1, CNRS UMR5240, Laboratoire de Microbiologie, Adaptation et Pathogénie, 69621 Villeurbanne, France
| | - Georgi Muskhelishvili
- School of Natural Sciences, Agricultural University of Georgia, Davit Aghmashenebeli Alley 240, 0159 Tbilisi, Georgia
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Patterson-West J, Tai CH, Son B, Hsieh ML, Iben JR, Hinton DM. Overexpression of the Bacteriophage T4 motB Gene Alters H-NS Dependent Repression of Specific Host DNA. Viruses 2021; 13:v13010084. [PMID: 33435393 PMCID: PMC7827196 DOI: 10.3390/v13010084] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/04/2021] [Accepted: 01/07/2021] [Indexed: 12/17/2022] Open
Abstract
The bacteriophage T4 early gene product MotB binds tightly but nonspecifically to DNA, copurifies with the host Nucleoid Associated Protein (NAP) H-NS in the presence of DNA and improves T4 fitness. However, the T4 transcriptome is not significantly affected by a motB knockdown. Here we have investigated the phylogeny of MotB and its predicted domains, how MotB and H-NS together interact with DNA, and how heterologous overexpression of motB impacts host gene expression. We find that motB is highly conserved among Tevenvirinae. Although the MotB sequence has no homology to proteins of known function, predicted structure homology searches suggest that MotB is composed of an N-terminal Kyprides-Onzonis-Woese (KOW) motif and a C-terminal DNA-binding domain of oligonucleotide/oligosaccharide (OB)-fold; either of which could provide MotB’s ability to bind DNA. DNase I footprinting demonstrates that MotB dramatically alters the interaction of H-NS with DNA in vitro. RNA-seq analyses indicate that expression of plasmid-borne motB up-regulates 75 host genes; no host genes are down-regulated. Approximately 1/3 of the up-regulated genes have previously been shown to be part of the H-NS regulon. Our results indicate that MotB provides a conserved function for Tevenvirinae and suggest a model in which MotB functions to alter the host transcriptome, possibly by changing the association of H-NS with the host DNA, which then leads to conditions that are more favorable for infection.
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Affiliation(s)
- Jennifer Patterson-West
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (J.P.-W.); (B.S.); (M.-L.H.)
| | - Chin-Hsien Tai
- Center for Cancer Research, Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Bokyung Son
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (J.P.-W.); (B.S.); (M.-L.H.)
| | - Meng-Lun Hsieh
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (J.P.-W.); (B.S.); (M.-L.H.)
| | - James R. Iben
- Molecular Genomics Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Deborah M. Hinton
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (J.P.-W.); (B.S.); (M.-L.H.)
- Correspondence: ; Tel.: +1-301-496-9885
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29
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Prieto A, Bernabeu M, Falgenhauer L, Chakraborty T, Hüttener M, Juárez A. Overexpression of the third H-NS paralogue H-NS2 compensates fitness loss in hns mutants of the enteroaggregative Escherichia coli strain 042. Sci Rep 2020; 10:18131. [PMID: 33093592 PMCID: PMC7582179 DOI: 10.1038/s41598-020-75204-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 10/07/2020] [Indexed: 11/10/2022] Open
Abstract
Members of the H-NS protein family play a role both in the chromosome architecture and in the regulation of gene expression in bacteria. The genomes of the enterobacteria encode an H-NS paralogue, the StpA protein. StpA displays specific regulatory properties and provides a molecular backup for H-NS. Some enterobacteria also encode third H-NS paralogues. This is the case of the enteroaggregative E. coli (EAEC) strain 042, which encodes the hns, stpA and hns2 genes. We provide in this paper novel information about the role of the H-NS2 protein in strain 042. A C > T transition in the hns2 promoter leading to increased H-NS2 expression is readily selected in hns mutants. Increased H-NS2 expression partially compensates for H-NS loss. H-NS2 levels are critical for the strain 042 fitness. Under some circumstances, high H-NS2 expression levels dictated by the mutant hns2 promoter can be deleterious. The selection of T > C revertants or of clones harboring insertional inactivations of the hns2 gene can then occur. Temperature also plays a relevant role in the H-NS2 regulatory activity. At 37 °C, H-NS2 targets a subset of the H-NS repressed genes contributing to their silencing. When temperature drops to 25 °C, the repressory ability of H-NS2 is significantly reduced. At low temperature, H-NS plays the main repressory role.
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Affiliation(s)
- A Prieto
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - M Bernabeu
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - L Falgenhauer
- Institute of Hygiene and Environmental Medicine, Justus Liebig University Giessen, Schubertstrasse 81, 35392, Giessen, Germany.,German Center for Infection Research DZIF, Partner Site Giessen-Marburg-Langen, Campus, Giessen, Germany
| | - T Chakraborty
- German Center for Infection Research DZIF, Partner Site Giessen-Marburg-Langen, Campus, Giessen, Germany.,Institute of Medical Microbiology, Justus-Liebig University, Schubertstrasse 81, 35392, Giessen, Germany
| | - M Hüttener
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - A Juárez
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain. .,Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona, Spain.
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30
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Cristofalo M, Marrano CA, Salerno D, Corti R, Cassina V, Mammola A, Gherardi M, Sclavi B, Cosentino Lagomarsino M, Mantegazza F. Cooperative effects on the compaction of DNA fragments by the nucleoid protein H-NS and the crowding agent PEG probed by Magnetic Tweezers. Biochim Biophys Acta Gen Subj 2020; 1864:129725. [PMID: 32891648 DOI: 10.1016/j.bbagen.2020.129725] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 07/22/2020] [Accepted: 08/30/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND DNA bridging promoted by the H-NS protein, combined with the compaction induced by cellular crowding, plays a major role in the structuring of the E. coli genome. However, only few studies consider the effects of the physical interplay of these two factors in a controlled environment. METHODS We apply a single molecule technique (Magnetic Tweezers) to study the nanomechanics of compaction and folding kinetics of a 6 kb DNA fragment, induced by H-NS bridging and/or PEG crowding. RESULTS In the presence of H-NS alone, the DNA shows a step-wise collapse driven by the formation of multiple bridges, and little variations in the H-NS concentration-dependent unfolding force. Conversely, the DNA collapse force observed with PEG was highly dependent on the volume fraction of the crowding agent. The two limit cases were interpreted considering the models of loop formation in a pulled chain and pulling of an equilibrium globule respectively. CONCLUSIONS We observed an evident cooperative effect between H-NS activity and the depletion of forces induced by PEG. GENERAL SIGNIFICANCE Our data suggest a double role for H-NS in enhancing compaction while forming specific loops, which could be crucial in vivo for defining specific mesoscale domains in chromosomal regions in response to environmental changes.
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Affiliation(s)
- M Cristofalo
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy
| | - C A Marrano
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy
| | - D Salerno
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy
| | - R Corti
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy
| | - V Cassina
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy
| | - A Mammola
- Università degli Studi di Milano, Via Celoria 16, 20133 Milano (MI), Italy
| | - M Gherardi
- Università degli Studi di Milano, Via Celoria 16, 20133 Milano (MI), Italy; IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milano (MI), Italy; I.N.F.N. Sezione di Milano, Via Celoria 16, 20133 Milano (MI), Italy
| | - B Sclavi
- Université Pierre et Marie Curie, Institut de Biologie Paris Seine, 7-9 Quai Saint Bernard, 75005 Paris, France
| | - M Cosentino Lagomarsino
- Università degli Studi di Milano, Via Celoria 16, 20133 Milano (MI), Italy; IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milano (MI), Italy; I.N.F.N. Sezione di Milano, Via Celoria 16, 20133 Milano (MI), Italy
| | - F Mantegazza
- School of Medicine and Surgery, Nanomedicine Center NANOMIB, University of Milano-Bicocca, via Raoul Follereau 3, 20854, Vedano al Lambro (MB), Italy.
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31
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Bischof K, Schiffer D, Trunk S, Höfler T, Hopfer A, Rechberger G, Koraimann G. Regulation of R1 Plasmid Transfer by H-NS, ArcA, TraJ, and DNA Sequence Elements. Front Microbiol 2020; 11:1254. [PMID: 32595626 PMCID: PMC7303359 DOI: 10.3389/fmicb.2020.01254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 05/18/2020] [Indexed: 11/17/2022] Open
Abstract
In conjugative elements such as integrating conjugative elements (ICEs) or conjugative plasmids (CPs) transcription of DNA transfer genes is a prerequisite for cells to become transfer competent, i.e., capable of delivering plasmid DNA via bacterial conjugation into new host bacteria. In the large family of F-like plasmids belonging to the MobF12A group, transcription of DNA transfer genes is tightly controlled and dependent on the activation of a single promoter, designated PY. Plasmid encoded TraJ and chromosomally encoded ArcA proteins are known activators, whereas the nucleoid associated protein heat-stable nucleoid structuring (H-NS) silences the PY promoter. To better understand the role of these proteins in PY promoter activation, we performed in vitro DNA binding studies using purified H-NS, ArcA, and TraJR1 (TraJ encoded by the conjugative resistance plasmid R1). All proteins could bind to R1PY DNA with high affinities; however, only ArcA was found to be highly sequence specific. DNase I footprinting studies revealed three H-NS binding sites, confirmed the binding site for ArcA, and suggested that TraJ contacts a dyad symmetry DNA sequence located between −51 and −38 in the R1PY promoter region. Moreover, TraJR1 and ArcA supplied together changed the H-NS specific protection pattern suggesting that these proteins are able to replace H-NS from R1PY regions proximal to the transcription start site. Our findings were corroborated by PY-lacZ reporter fusions with a series of site specific R1PY promoter mutations. Sequential changes of some critical DNA bases in the TraJ binding site (jbs) from plasmid R1 to plasmid F led to a remarkable specificity switch: The PY promoter became activatable by F encoded TraJ whereas TraJR1 lost its activation function. The R1PY mutagenesis approach also confirmed the requirement for the host-encoded response-regulator ArcA and indicated that the sequence context, especially in the −35 region is critical for PY regulation and function.
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Affiliation(s)
- Karin Bischof
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Doris Schiffer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Sarah Trunk
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Thomas Höfler
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Anja Hopfer
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Gerald Rechberger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Günther Koraimann
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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32
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The Antiactivator of Type III Secretion, OspD1, Is Transcriptionally Regulated by VirB and H-NS from Remote Sequences in Shigella flexneri. J Bacteriol 2020; 202:JB.00072-20. [PMID: 32123035 DOI: 10.1128/jb.00072-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 02/24/2020] [Indexed: 01/08/2023] Open
Abstract
Shigella species, the causal agents of bacillary dysentery, use a type III secretion system (T3SS) to inject two waves of virulence proteins, known as effectors, into the colonic epithelium to subvert host cell machinery. Prior to host cell contact and secretion of the first wave of T3SS effectors, OspD1, an effector and antiactivator protein, prevents premature production of the second wave of effectors. Despite this important role, regulation of the ospD1 gene is not well understood. While ospD1 belongs to the large regulon of VirB, a transcriptional antisilencing protein that counters silencing mediated by the histone-like nucleoid structuring protein H-NS, it remains unclear if VirB directly or indirectly regulates ospD1 Additionally, it is not known if ospD1 is regulated by H-NS. Here, we identify the primary ospD1 transcription start site (+1) and show that the ospD1 promoter is remotely regulated by both VirB and H-NS. Our findings demonstrate that VirB regulation of ospD1 requires at least one of the two newly identified VirB regulatory sites, centered at -978 and -1270 relative to the ospD1 +1. Intriguingly, one of these sites lies on a 193-bp sequence found in three conserved locations on the large virulence plasmids of Shigella The region required for H-NS-dependent silencing of ospD1 lies between -1120 and -820 relative to the ospD1 +1. Thus, our study provides further evidence that cis-acting regulatory sequences for transcriptional antisilencers and silencers, such as VirB and H-NS, can lie far upstream of the canonical bacterial promoter region (i.e., -250 to +1).IMPORTANCE Transcriptional silencing and antisilencing mechanisms regulate virulence gene expression in many important bacterial pathogens. In Shigella species, plasmid-borne virulence genes, such as those encoding the type III secretion system (T3SS), are silenced by the histone-like nucleoid structuring protein H-NS and antisilenced by VirB. Previous work at the plasmid-borne icsP locus revealed that VirB binds to a remotely located cis-acting regulatory site to relieve transcriptional silencing mediated by H-NS. Here, we characterize a second example of remote VirB antisilencing at ospD1, which encodes a T3SS antiactivator and effector. Our study highlights that remote transcriptional silencing and antisilencing occur more frequently in Shigella than previously thought, and it raises the possibility that long-range transcriptional regulation in bacteria is commonplace.
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33
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Qin L, Bdira FB, Sterckx YGJ, Volkov AN, Vreede J, Giachin G, van Schaik P, Ubbink M, Dame RT. Structural basis for osmotic regulation of the DNA binding properties of H-NS proteins. Nucleic Acids Res 2020; 48:2156-2172. [PMID: 31925429 PMCID: PMC7039000 DOI: 10.1093/nar/gkz1226] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/29/2019] [Accepted: 12/19/2019] [Indexed: 01/07/2023] Open
Abstract
H-NS proteins act as osmotic sensors translating changes in osmolarity into altered DNA binding properties, thus, regulating enterobacterial genome organization and genes transcription. The molecular mechanism underlying the switching process and its conservation among H-NS family members remains elusive. Here, we focus on the H-NS family protein MvaT from Pseudomonas aeruginosa and demonstrate experimentally that its protomer exists in two different conformations, corresponding to two different functional states. In the half-opened state (dominant at low salt) the protein forms filaments along DNA, in the fully opened state (dominant at high salt) the protein bridges DNA. This switching is a direct effect of ionic strength on electrostatic interactions between the oppositely charged DNA binding and N-terminal domains of MvaT. The asymmetric charge distribution and intramolecular interactions are conserved among the H-NS family of proteins. Therefore, our study establishes a general paradigm for the molecular mechanistic basis of the osmosensitivity of H-NS proteins.
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Affiliation(s)
- Liang Qin
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands.,Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Fredj Ben Bdira
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands.,Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Yann G J Sterckx
- Laboratory of Medical Biochemistry, University of Antwerp, Campus Drie Eiken, University Square 1, 2610 Wilrijk, Belgium
| | - Alexander N Volkov
- VIB-VUB Structural Biology Research Center, Pleinlaan 2, 1050 Brussels, Belgium.,Jean Jeener NMR Centre, VUB, Pleinlaan 2, 1050 Brussels, Belgium
| | - Jocelyne Vreede
- Department of Computational Chemistry, Van't Hoff Institute for Molecular Sciences, University of Amsterdam Science Park 904, 1098 XH Amsterdam, the Netherlands
| | - Gabriele Giachin
- Structural Biology Group, European Synchrotron Radiation Facility (ESRF), Grenoble, France
| | - Peter van Schaik
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands.,Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
| | - Marcellus Ubbink
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands
| | - Remus T Dame
- Department of Macromolecular Biochemistry, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, the Netherlands.,Centre for Microbial Cell Biology, Leiden University, Einsteinweg 55, 2333CC Leiden, the Netherlands
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Chaparian RR, Tran MLN, Miller Conrad LC, Rusch DB, van Kessel JC. Global H-NS counter-silencing by LuxR activates quorum sensing gene expression. Nucleic Acids Res 2020; 48:171-183. [PMID: 31745565 PMCID: PMC7145609 DOI: 10.1093/nar/gkz1089] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 10/15/2019] [Accepted: 11/18/2019] [Indexed: 01/03/2023] Open
Abstract
Bacteria coordinate cellular behaviors using a cell-cell communication system termed quorum sensing. In Vibrio harveyi, the master quorum sensing transcription factor LuxR directly regulates >100 genes in response to changes in population density. Here, we show that LuxR derepresses quorum sensing loci by competing with H-NS, a global transcriptional repressor that oligomerizes on DNA to form filaments and bridges. We first identified H-NS as a repressor of bioluminescence gene expression, for which LuxR is a required activator. In an hns deletion strain, LuxR is no longer necessary for transcription activation of the bioluminescence genes, suggesting that the primary role of LuxR is to displace H-NS to derepress gene expression. Using RNA-seq and ChIP-seq, we determined that H-NS and LuxR co-regulate and co-occupy 28 promoters driving expression of 63 genes across the genome. ChIP-PCR assays show that as autoinducer concentration increases, LuxR protein accumulates at co-occupied promoters while H-NS protein disperses. LuxR is sufficient to evict H-NS from promoter DNA in vitro, which is dependent on LuxR DNA binding activity. From these findings, we propose a model in which LuxR serves as a counter-silencer at H-NS-repressed quorum sensing loci by disrupting H-NS nucleoprotein complexes that block transcription.
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Affiliation(s)
| | - Minh L N Tran
- Department of Chemistry, San Jose State University, San Jose, CA, USA
| | | | - Douglas B Rusch
- Center for Genomics and Bioinformatics, Indiana University, Bloomington, IN, USA
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Abstract
How genomes are organized within cells and how the 3D architecture of a genome influences cellular functions are significant questions in biology. A bacterial genomic DNA resides inside cells in a highly condensed and functionally organized form called nucleoid (nucleus-like structure without a nuclear membrane). The Escherichia coli chromosome or nucleoid is composed of the genomic DNA, RNA, and protein. The nucleoid forms by condensation and functional arrangement of a single chromosomal DNA with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. Although a high-resolution structure of a bacterial nucleoid is yet to come, five decades of research has established the following salient features of the E. coli nucleoid elaborated below: 1) The chromosomal DNA is on the average a negatively supercoiled molecule that is folded as plectonemic loops, which are confined into many independent topological domains due to supercoiling diffusion barriers; 2) The loops spatially organize into megabase size regions called macrodomains, which are defined by more frequent physical interactions among DNA sites within the same macrodomain than between different macrodomains; 3) The condensed and spatially organized DNA takes the form of a helical ellipsoid radially confined in the cell; and 4) The DNA in the chromosome appears to have a condition-dependent 3-D structure that is linked to gene expression so that the nucleoid architecture and gene transcription are tightly interdependent, influencing each other reciprocally. Current advents of high-resolution microscopy, single-molecule analysis and molecular structure determination of the components are expected to reveal the total structure and function of the bacterial nucleoid.
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Affiliation(s)
- Subhash C. Verma
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
| | - Zhong Qian
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sankar L. Adhya
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail: (SCV); (SLA)
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36
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Qin L, Erkelens AM, Ben Bdira F, Dame RT. The architects of bacterial DNA bridges: a structurally and functionally conserved family of proteins. Open Biol 2019; 9:190223. [PMID: 31795918 PMCID: PMC6936261 DOI: 10.1098/rsob.190223] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 11/08/2019] [Indexed: 12/15/2022] Open
Abstract
Every organism across the tree of life compacts and organizes its genome with architectural chromatin proteins. While eukaryotes and archaea express histone proteins, the organization of bacterial chromosomes is dependent on nucleoid-associated proteins. In Escherichia coli and other proteobacteria, the histone-like nucleoid structuring protein (H-NS) acts as a global genome organizer and gene regulator. Functional analogues of H-NS have been found in other bacterial species: MvaT in Pseudomonas species, Lsr2 in actinomycetes and Rok in Bacillus species. These proteins complement hns- phenotypes and have similar DNA-binding properties, despite their lack of sequence homology. In this review, we focus on the structural and functional characteristics of these four architectural proteins. They are able to bridge DNA duplexes, which is key to genome compaction, gene regulation and their response to changing conditions in the environment. Structurally the domain organization and charge distribution of these proteins are conserved, which we suggest is at the basis of their conserved environment responsive behaviour. These observations could be used to find and validate new members of this protein family and to predict their response to environmental changes.
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Affiliation(s)
- L. Qin
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - A. M. Erkelens
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - F. Ben Bdira
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
| | - R. T. Dame
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC Leiden, The Netherlands
- Centre for Microbial Cell Biology, Leiden University, Leiden, The Netherlands
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37
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Growth Phase-Dependent Chromosome Condensation and Heat-Stable Nucleoid-Structuring Protein Redistribution in Escherichia coli under Osmotic Stress. J Bacteriol 2019; 201:JB.00469-19. [PMID: 31481544 DOI: 10.1128/jb.00469-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 08/29/2019] [Indexed: 12/11/2022] Open
Abstract
The heat-stable nucleoid-structuring (H-NS) protein is a global transcriptional regulator implicated in coordinating the expression of over 200 genes in Escherichia coli, including many involved in adaptation to osmotic stress. We have applied superresolved microscopy to quantify the intracellular and spatial reorganization of H-NS in response to a rapid osmotic shift. We found that H-NS showed growth phase-dependent relocalization in response to hyperosmotic shock. In stationary phase, H-NS detached from a tightly compacted bacterial chromosome and was excluded from the nucleoid volume over an extended period of time. This behavior was absent during rapid growth but was induced by exposing the osmotically stressed culture to a DNA gyrase inhibitor, coumermycin. This chromosomal compaction/H-NS exclusion phenomenon occurred in the presence of either potassium or sodium ions and was independent of the presence of stress-responsive sigma factor σS and of the H-NS paralog StpA.IMPORTANCE The heat-stable nucleoid-structuring (H-NS) protein coordinates the expression of over 200 genes in E. coli, with a large number involved in both bacterial virulence and drug resistance. We report on the novel observation of a dynamic compaction of the bacterial chromosome in response to exposure to high levels of salt. This stress response results in the detachment of H-NS proteins and their subsequent expulsion to the periphery of the cells. We found that this behavior is related to mechanical properties of the bacterial chromosome, in particular, to how tightly twisted and coiled is the chromosomal DNA. This behavior might act as a biomechanical response to stress that coordinates the expression of genes involved in adapting bacteria to a salty environment.
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38
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Comparative analysis of Aliivibrio logei luxR1 and luxR2 genes regulation in Escherichia coli cells. Arch Microbiol 2019; 201:1415-1425. [PMID: 31392374 DOI: 10.1007/s00203-019-01691-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 05/16/2019] [Accepted: 06/05/2019] [Indexed: 10/26/2022]
Abstract
Regulation of Aliivibrio logei luxR1 and luxR2 genes was evaluated in Escherichia coli cells with use of transcriptional fusions of luxR1 and luxR2 promoter/operator regions with the Photorhabdus luminescens luxCDABE reporter gene cassette. Expression of the luxR1 and luxR2 genes was shown to largely depend on the CRP as activator. The hns::kan mutation increases the expression of luxR2 gene by two to three orders of magnitude and luxR1 gene by two to threefold. The LuxR1 and LuxR2 proteins in the presence of autoinducer (N-acyl homoserine lactone, AI) separately as well as together considerably enhanced the transcription of the luxR2 gene. In contrast, the transcription of luxR1 gene decreases depending on AI concentration in the presence of the luxR1 and luxR2 genes combination. It was identified that the promoter region of luxR2 gene consists of two promoters: Pcrp is located downstream of the crp box and Plux-box is located between the crp box and the lux box.
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Gulvady R, Gao Y, Kenney LJ, Yan J. A single molecule analysis of H-NS uncouples DNA binding affinity from DNA specificity. Nucleic Acids Res 2019; 46:10216-10224. [PMID: 30239908 PMCID: PMC6212787 DOI: 10.1093/nar/gky826] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2018] [Accepted: 09/06/2018] [Indexed: 12/29/2022] Open
Abstract
Heat-stable nucleoid structuring protein (H-NS) plays a crucial role in gene silencing within prokaryotic cells and is important in pathogenesis. It was reported that H-NS silences nearly 5% of the genome, yet the molecular mechanism of silencing is not well understood. Here, we employed a highly-sensitive single-molecule counting approach, and measured the dissociation constant (KD) of H-NS binding to single DNA binding sites. Charged residues in the linker domain of H-NS provided the most significant contribution to DNA binding affinity. Although H-NS was reported to prefer A/T-rich DNA (a feature of pathogenicity islands) over G/C-rich DNA, the dissociation constants obtained from such sites were nearly identical. Using a hairpin unzipping assay, we were able to uncouple non-specific DNA binding steps from nucleation site binding and subsequent polymerization. We propose a model in which H-NS initially engages with non-specific DNA via reasonably high affinity (∼60 nM KD) electrostatic interactions with basic residues in the linker domain. This initial contact enables H-NS to search along the DNA for specific nucleation sites that drive subsequent polymerization and gene silencing.
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Affiliation(s)
- Ranjit Gulvady
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Yunfeng Gao
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore
| | - Linda J Kenney
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Jesse Brown Veterans Administration Medical Center, Chicago, IL 6061, USA.,Department of Microbiology and Immunology, University of Illinois-Chicago, Chicago, IL 60612, USA.,Department of Biochemistry, National University of Singapore, Singapore 117596, Singapore
| | - Jie Yan
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Singapore.,Department of Physics, National University of Singapore, Singapore 117542, Singapore.,Centre for Bioimaging Sciences, National University of Singapore, Singapore 117546, Singapore
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40
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Niccum BA, Lee H, MohammedIsmail W, Tang H, Foster PL. The Symmetrical Wave Pattern of Base-Pair Substitution Rates across the Escherichia coli Chromosome Has Multiple Causes. mBio 2019; 10:e01226-19. [PMID: 31266871 PMCID: PMC6606806 DOI: 10.1128/mbio.01226-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 05/28/2019] [Indexed: 01/28/2023] Open
Abstract
Mutation accumulation experiments followed by whole-genome sequencing have revealed that, for several bacterial species, the rate of base-pair substitutions (BPSs) is not constant across the chromosome but varies in a wave-like pattern that is symmetrical about the origin of replication. The experiments reported here demonstrated that, in Escherichia coli, several interacting factors determine the wave. The origin is a major driver of BPS rates. When it is relocated, the BPS rates in a 1,000-kb region surrounding the new origin reproduce the pattern that surrounds the normal origin. However, the pattern across distant regions of the chromosome is unaltered and thus must be determined by other factors. Increasing the deoxynucleoside triphosphate (dNTP) concentration shifts the wave pattern away from the origin, supporting the hypothesis that fluctuations in dNTP pools coincident with replication firing contribute to the variations in the mutation rate. The nucleoid binding proteins (HU and Fis) and the terminus organizing protein (MatP) are also major factors. These proteins alter the three-dimensional structure of the DNA, and results suggest that mutation rates increase when highly structured DNA is replicated. Biases in error correction by proofreading and mismatch repair, both of which may be responsive to dNTP concentrations and DNA structure, also are major determinants of the wave pattern. These factors should apply to most bacterial and, possibly, eukaryotic genomes and suggest that different areas of the genome evolve at different rates.IMPORTANCE It has been found in several species of bacteria that the rate at which single base pairs are mutated is not constant across the genome but varies in a wave-like pattern that is symmetrical about the origin of replication. Using Escherichia coli as our model system, we show that this pattern is the result of several interconnected factors. First, the timing and progression of replication are important in determining the wave pattern. Second, the three-dimensional structure of the DNA is also a factor, and the results suggest that mutation rates increase when highly structured DNA is replicated. Finally, biases in error correction, which may be responsive both to the progression of DNA synthesis and to DNA structure, are major determinants of the wave pattern. These factors should apply to most bacterial and, possibly, eukaryotic genomes and suggest that different areas of the genome evolve at different rates.
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Affiliation(s)
- Brittany A Niccum
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Heewook Lee
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana, USA
| | - Wazim MohammedIsmail
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana, USA
| | - Haixu Tang
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, Indiana, USA
| | - Patricia L Foster
- Department of Biology, Indiana University, Bloomington, Indiana, USA
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41
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H-NS Family Members MvaT and MvaU Regulate the Pseudomonas aeruginosa Type III Secretion System. J Bacteriol 2019; 201:JB.00054-19. [PMID: 30782629 DOI: 10.1128/jb.00054-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 02/07/2019] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen capable of causing severe disease in immunocompromised individuals. A major P. aeruginosa virulence factor is the type III secretion system (T3SS). The T3SS is used to translocate effector proteins into host cells, causing cytotoxicity. The T3SS is under the transcriptional control of the master regulator ExsA. ExsA is encoded in the exsCEBA operon and autoregulates transcription via the P exsC promoter. There is also a Vfr-dependent promoter (P exsA ) located in the intergenic region between exsB and exsA A previous chromatin immunoprecipitation (ChIP)-on-chip experiment identified strong binding signatures for MvaT and MvaU in the intergenic region containing the P exsA promoter. MvaT and MvaU are DNA-binding histone-like nucleoid-structuring proteins that can repress gene expression. As predicted from the previous ChIP data, purified MvaT specifically bound to the P exsA promoter region in electrophoretic mobility shift assays. Whereas disruption of mvaT or mvaU by either transposon insertion or clustered regularly interspaced short palindromic repeat interference (CRISPRi) derepressed P exsA promoter activity and T3SS gene expression, overexpression of MvaT or MvaU inhibited P exsA promoter activity. Disruption of mvaT, however, did not suppress the Vfr requirement for P exsA promoter activity. Mutated MvaT/MvaU defective in transcriptional silencing exhibited dominant negative activity, resulting in a significant increase in P exsA promoter activity. Because no effect of MvaT or MvaU on Vfr expression was detected, we propose a model in which the primary effect of MvaT/MvaU on T3SS gene expression is through direct silencing of the P exsA promoter.IMPORTANCE Global regulatory systems play a prominent role in controlling the P. aeruginosa T3SS and include the Gac/RsmA, c-di-GMP, and Vfr-cAMP signaling pathways. Many of these pathways appear to directly or indirectly influence exsA transcription or translation. In this study, the histone-like proteins MvaT and MvaU are added to the growing list of global regulators that control the T3SS. MvaT and MvaU bind AT-rich regions in the genome and silence xenogeneic genes, including pathogenicity islands. The T3SS gene cluster has been horizontally transmitted among many Gram-negative pathogens. Control by MvaT/MvaU may reflect a residual effect that has persisted since the initial acquisition of the gene cluster, subsequently imposing a requirement for active regulatory mechanisms to override MvaT/MvaU-mediated silencing.
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Shahul Hameed UF, Liao C, Radhakrishnan AK, Huser F, Aljedani SS, Zhao X, Momin AA, Melo FA, Guo X, Brooks C, Li Y, Cui X, Gao X, Ladbury JE, Jaremko Ł, Jaremko M, Li J, Arold ST. H-NS uses an autoinhibitory conformational switch for environment-controlled gene silencing. Nucleic Acids Res 2019; 47:2666-2680. [PMID: 30597093 PMCID: PMC6411929 DOI: 10.1093/nar/gky1299] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Revised: 12/11/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
As an environment-dependent pleiotropic gene regulator in Gram-negative bacteria, the H-NS protein is crucial for adaptation and toxicity control of human pathogens such as Salmonella, Vibrio cholerae or enterohaemorrhagic Escherichia coli. Changes in temperature affect the capacity of H-NS to form multimers that condense DNA and restrict gene expression. However, the molecular mechanism through which H-NS senses temperature and other physiochemical parameters remains unclear and controversial. Combining structural, biophysical and computational analyses, we show that human body temperature promotes unfolding of the central dimerization domain, breaking up H-NS multimers. This unfolding event enables an autoinhibitory compact H-NS conformation that blocks DNA binding. Our integrative approach provides the molecular basis for H-NS-mediated environment-sensing and may open new avenues for the control of pathogenic multi-drug resistant bacteria.
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Affiliation(s)
- Umar F Shahul Hameed
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
| | - Chenyi Liao
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA
| | - Anand K Radhakrishnan
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
| | - Franceline Huser
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
| | - Safia S Aljedani
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
| | - Xiaochuan Zhao
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA
| | - Afaque A Momin
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
| | - Fernando A Melo
- Department of Physics (IBILCE), São Paulo State University, São José do Rio Preto, São Paulo, Brazil
| | - Xianrong Guo
- King Abdullah University of Science and Technology (KAUST), Imaging and Characterization Core Lab, Thuwal, 23955-6900, Saudi Arabia
| | - Claire Brooks
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA
| | - Yu Li
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering Division (BESE), Thuwal, 23955-6900, Saudi Arabia
| | - Xuefeng Cui
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering Division (BESE), Thuwal, 23955-6900, Saudi Arabia
| | - Xin Gao
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering Division (BESE), Thuwal, 23955-6900, Saudi Arabia
| | - John E Ladbury
- School of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Łukasz Jaremko
- King Abdullah University of Science and Technology (KAUST), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955-6900, Saudi Arabia
| | - Mariusz Jaremko
- King Abdullah University of Science and Technology (KAUST), Division of Biological and Environmental Sciences and Engineering, Thuwal, 23955-6900, Saudi Arabia
| | - Jianing Li
- Department of Chemistry, The University of Vermont, Burlington, VT 05405, USA
| | - Stefan T Arold
- King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center (CBRC), Division of Biological and Environmental Sciences and Engineering (BESE), Thuwal, 23955-6900,Saudi Arabia
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43
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Predicting the mechanism and rate of H-NS binding to AT-rich DNA. PLoS Comput Biol 2019; 15:e1006845. [PMID: 30845209 PMCID: PMC6424460 DOI: 10.1371/journal.pcbi.1006845] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 03/19/2019] [Accepted: 02/02/2019] [Indexed: 12/21/2022] Open
Abstract
Bacteria contain several nucleoid-associated proteins that organize their genomic DNA into the nucleoid by bending, wrapping or bridging DNA. The Histone-like Nucleoid Structuring protein H-NS found in many Gram-negative bacteria is a DNA bridging protein and can structure DNA by binding to two separate DNA duplexes or to adjacent sites on the same duplex, depending on external conditions. Several nucleotide sequences have been identified to which H-NS binds with high affinity, indicating H-NS prefers AT-rich DNA. To date, highly detailed structural information of the H-NS DNA complex remains elusive. Molecular simulation can complement experiments by modelling structures and their time evolution in atomistic detail. In this paper we report an exploration of the different binding modes of H-NS to a high affinity nucleotide sequence and an estimate of the associated rate constant. By means of molecular dynamics simulations, we identified three types of binding for H-NS to AT-rich DNA. To further sample the transitions between these binding modes, we performed Replica Exchange Transition Interface Sampling, providing predictions of the mechanism and rate constant of H-NS binding to DNA. H-NS interacts with the DNA through a conserved QGR motif, aided by a conserved arginine at position 93. The QGR motif interacts first with phosphate groups, followed by the formation of hydrogen bonds between acceptors in the DNA minor groove and the sidechains of either Q112 or R114. After R114 inserts into the minor groove, the rest of the QGR motif follows. Full insertion of the QGR motif in the minor groove is stable over several tens of nanoseconds, and involves hydrogen bonds between the bases and both backbone and sidechains of the QGR motif. The rate constant for the process of H-NS binding to AT-rich DNA resulting in full insertion of the QGR motif is in the order of 106 M−1s−1, which is rate limiting compared to the non-specific association of H-NS to the DNA backbone at a rate of 108 M−1s−1. The Histone-like Nucleoid Structuring protein (H-NS) occurs in enterobacteria, such as Salmonella typhimurium and Escherichia coli, and structures DNA by forming filaments along DNA duplexes. Several nucleotide sequences have been identified to which H-NS binds with high affinity. Yet, obtaining highly detailed structural information of the H-NS DNA complex has proven to be a major challenge, which has not been yet resolved. By employing molecular dynamics simulations we were able to provide high resolution insights into the mechanism of DNA binding by H-NS. We identified various ways in which H-NS can bind to DNA. In all binding events, a conserved region in the protein initiates the association of H-NS to DNA. Our results show that H-NS binds in the minor groove of AT-rich DNA via a series of intermediate steps. Using advanced molecular simulation methods we predicted that the process of H-NS binding to the DNA backbone to full insertion into the minor groove occurs in the order of a million times per second, which is slower than the non-specific association of H-NS to the DNA backbone.
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44
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Kapshikar RM, Gowrishankar J. Direct inhibition of transcription in vitro by the isolated N-terminal domain of the Escherichia coli nucleoid-associated protein H-NS and by its paralogue Hha. MICROBIOLOGY-SGM 2019; 165:463-474. [PMID: 30724731 DOI: 10.1099/mic.0.000780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
H-NS is an abundant nucleoid-associated protein in the enterobacteria that mediates both chromatin compaction and transcriptional silencing of numerous genes, especially those that have been acquired by horizontal transfer or that are involved in virulence functions. With two dimerization domains (N-terminal and central) and a C-terminal DNA-binding domain, the 15 kDa H-NS polypeptide can assemble as long polymeric filaments on DNA, and mutations in any of the three domains confer a dominant-negative phenotype in vivo by a subunit-poisoning mechanism. Here we confirm that several of these mutants [L26P, I119T and a truncation beyond residue 92(Δ93)] are also dominant-negative in vitro, in that they reverse the inhibition imposed by native H-NS in two different transcription assay formats (initiation+elongation, or elongation alone). On the other hand, another dominant-negative truncation mutant Δ64 (which possesses only the protein's N-terminal domain) per se completely and unexpectedly inhibited transcription in both assay formats. The Hha protein, which is a paralogue of H-NS and resembles its isolated N-terminal domain, also behaved like Δ64 as an inhibitor of transcription in vitro. We propose that under certain growth conditions, Escherichia coli RNA polymerase may be the direct inhibitory target of Hha, and that this effect is experimentally mimicked by the isolated N-terminal domain of H-NS.
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Affiliation(s)
- Rajvardhan M Kapshikar
- 1Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India.,2Graduate Studies, Manipal Academy of Higher Education, Manipal, India
| | - J Gowrishankar
- 1Laboratory of Bacterial Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, India
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Meenakshi S, Karthik M, Munavar MH. A putative curved DNA region upstream of rcsA in Escherichia coli plays a key role in transcriptional regulation by H-NS. FEBS Open Bio 2018; 8:1209-1218. [PMID: 30087827 PMCID: PMC6070653 DOI: 10.1002/2211-5463.12348] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 11/24/2022] Open
Abstract
It is well established that in Escherichia coli, the histone‐like nucleoid structuring (H‐NS) protein also functions as negative regulator of rcsA transcription. However, the exact mode of regulation of rcsA transcription by H‐NS has not been studied extensively. Here, we report the multicopy effect of dominant‐negative hns alleles on the transcription of rcsA based on expression of cps‐lac transcriptional fusion in ∆lon, ∆lon rpoB12, ∆lon rpoB77 and lon+ strains. Our results indicate that H‐NS defective in recognizing curved DNA fails to repress rcsA transcription significantly, while nonoligomeric H‐NS molecules still retain the repressor activity to an appreciable extent. Together with bioinformatics analysis, our study envisages a critical role for the putative curved DNA region present upstream of rcsA promoter in the transcriptional regulation of rcsA by H‐NS.
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Affiliation(s)
- Shanmugaraja Meenakshi
- Department of Molecular Biology School of Biological Sciences Centre for Advanced Studies in Functional and Organismal Genomics Madurai Kamaraj University [University with Potential for Excellence] Madurai India
| | - Maruthan Karthik
- Department of Molecular Biology School of Biological Sciences Centre for Advanced Studies in Functional and Organismal Genomics Madurai Kamaraj University [University with Potential for Excellence] Madurai India
| | - M Hussain Munavar
- Department of Molecular Biology School of Biological Sciences Centre for Advanced Studies in Functional and Organismal Genomics Madurai Kamaraj University [University with Potential for Excellence] Madurai India
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46
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Patterson-West J, Arroyo-Mendoza M, Hsieh ML, Harrison D, Walker MM, Knipling L, Hinton DM. The Bacteriophage T4 MotB Protein, a DNA-Binding Protein, Improves Phage Fitness. Viruses 2018; 10:v10070343. [PMID: 29949907 PMCID: PMC6070864 DOI: 10.3390/v10070343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/15/2018] [Accepted: 06/25/2018] [Indexed: 01/21/2023] Open
Abstract
The lytic bacteriophage T4 employs multiple phage-encoded early proteins to takeover the Escherichia coli host. However, the functions of many of these proteins are not known. In this study, we have characterized the T4 early gene motB, located in a dispensable region of the T4 genome. We show that heterologous production of MotB is highly toxic to E. coli, resulting in cell death or growth arrest depending on the strain and that the presence of motB increases T4 burst size 2-fold. Previous work suggested that motB affects middle gene expression, but our transcriptome analyses of T4 motBam vs. T4 wt infections reveal that only a few late genes are mildly impaired at 5 min post-infection, and expression of early and middle genes is unaffected. We find that MotB is a DNA-binding protein that binds both unmodified host and T4 modified [(glucosylated, hydroxymethylated-5 cytosine, (GHme-C)] DNA with no detectable sequence specificity. Interestingly, MotB copurifies with the host histone-like proteins, H-NS and StpA, either directly or through cobinding to DNA. We show that H-NS also binds modified T4 DNA and speculate that MotB may alter how H-NS interacts with T4 DNA, host DNA, or both, thereby improving the growth of the phage.
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Affiliation(s)
- Jennifer Patterson-West
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Melissa Arroyo-Mendoza
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Meng-Lun Hsieh
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Danielle Harrison
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Morgan M Walker
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Leslie Knipling
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
| | - Deborah M Hinton
- Gene Expression and Regulation Section, Laboratory of Cell and Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0830, USA.
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47
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Weatherspoon-Griffin N, Picker MA, Pew KL, Park HS, Ginete DR, Karney MMA, Usufzy P, Castellanos MI, Duhart JC, Harrison DJ, Socea JN, Karabachev AD, Hensley CT, Howerton AJ, Ojeda-Daulo R, Immak JA, Wing HJ. Insights into transcriptional silencing and anti-silencing in Shigella flexneri: a detailed molecular analysis of the icsP virulence locus. Mol Microbiol 2018; 108:505-518. [PMID: 29453862 PMCID: PMC6311345 DOI: 10.1111/mmi.13932] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2018] [Indexed: 11/28/2022]
Abstract
Transcriptional silencing and anti-silencing mechanisms modulate bacterial physiology and virulence in many human pathogens. In Shigella species, many virulence plasmid genes are silenced by the histone-like nucleoid structuring protein H-NS and anti-silenced by the virulence gene regulator VirB. Despite the key role that these regulatory proteins play in Shigella virulence, their mechanisms of transcriptional control remain poorly understood. Here, we characterize the regulatory elements and their relative spacing requirements needed for the transcriptional silencing and anti-silencing of icsP, a locus that requires remotely located regulatory elements for both types of transcriptional control. Our findings highlight the flexibility of the regulatory elements' positions with respect to each other, and yet, a molecular roadblock docked between the VirB binding site and the upstream H-NS binding region abolishes transcriptional anti-silencing by VirB, providing insight into transcriptional anti-silencing. Our study also raises the need to re-evaluate the currently proposed VirB binding site. Models of transcriptional silencing and anti-silencing at this genetic locus are presented, and the implications for understanding these regulatory mechanisms in bacteria are discussed.
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Affiliation(s)
| | | | - Krystle L. Pew
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Hiromichi S. Park
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Daren R. Ginete
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Monika MA. Karney
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Pashtana Usufzy
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Maria I. Castellanos
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Juan Carlos Duhart
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Dustin J. Harrison
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Jillian N. Socea
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | | | | | | | - Rosa Ojeda-Daulo
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Joy A. Immak
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
| | - Helen J. Wing
- School of Life Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154-4004, USA
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48
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Joyeux M. Role of Salt Valency in the Switch of H-NS Proteins between DNA-Bridging and DNA-Stiffening Modes. Biophys J 2018; 114:2317-2325. [PMID: 29576193 DOI: 10.1016/j.bpj.2018.02.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 02/05/2018] [Accepted: 02/28/2018] [Indexed: 11/17/2022] Open
Abstract
This work investigates the interactions of H-NS proteins and bacterial genomic DNA through computer simulations performed with a coarse-grained model. The model was developed specifically to study the switch of H-NS proteins from the DNA-stiffening to the DNA-bridging mode, which has been observed repeatedly upon addition of multivalent cations to the buffer but is still not understood. Unraveling the corresponding mechanism is all the more crucial, as the regulation properties of H-NS proteins, as well as other nucleoid proteins, are linked to their DNA-binding properties. The simulations reported here support a mechanism, according to which the primary role of multivalent cations consists in decreasing the strength of H-NS/DNA interactions compared to H-NS/H-NS interactions, with the latter ones becoming energetically favored with respect to the former ones above a certain threshold of the effective valency of the cations of the buffer. Below the threshold, H-NS dimers form filaments, which stretch along the DNA molecule but are quite inefficient in bridging genomically distant DNA sites (DNA-stiffening mode). In contrast, just above the threshold, H-NS dimers form three-dimensional clusters, which are able to connect DNA sites that are distant from the genomic point of view (DNA-bridging mode). The model provides clear rationales for the experimental observations that the switch between the two modes is a threshold effect and that the ability of H-NS dimers to form higher order oligomers is crucial for their bridging capabilities.
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Affiliation(s)
- Marc Joyeux
- Laboratoire Interdisciplinaire de Physique, CNRS and Université Grenoble Alpes, Grenoble, France.
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49
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Rangarajan AA, Schnetz K. Interference of transcription across H-NS binding sites and repression by H-NS. Mol Microbiol 2018; 108:226-239. [PMID: 29424946 DOI: 10.1111/mmi.13926] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2018] [Indexed: 11/28/2022]
Abstract
Nucleoid-associated protein H-NS represses transcription by forming extended DNA-H-NS complexes. Repression by H-NS operates mostly at the level of transcription initiation. Less is known about how DNA-H-NS complexes interfere with transcription elongation. In vitro H-NS has been shown to enhance RNA polymerase pausing and to promote Rho-dependent termination, while in vivo inhibition of Rho resulted in a decrease of the genome occupancy by H-NS. Here we show that transcription directed across H-NS binding regions relieves H-NS (and H-NS/StpA) mediated repression of promoters in these regions. Further, we observed a correlation of transcription across the H-NS-bound region and de-repression. The data suggest that the transcribing RNA polymerase is able to remodel the H-NS complex and/or dislodge H-NS from the DNA and thus relieve repression. Such an interference of transcription and H-NS mediated repression may imply that poorly transcribed AT-rich loci are prone to be repressed by H-NS, while efficiently transcribed loci escape repression.
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Affiliation(s)
| | - Karin Schnetz
- Institute for Genetics, University of Cologne, Zuelpicher Str. 47a, Cologne, Germany
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50
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Newman SL, Will WR, Libby SJ, Fang FC. The curli regulator CsgD mediates stationary phase counter-silencing of csgBA in Salmonella Typhimurium. Mol Microbiol 2018; 108:101-114. [PMID: 29388265 DOI: 10.1111/mmi.13919] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Revised: 01/26/2018] [Accepted: 01/26/2018] [Indexed: 12/23/2022]
Abstract
Integration of horizontally acquired genes into transcriptional networks is essential for the regulated expression of virulence in bacterial pathogens. In Salmonella enterica, expression of such genes is repressed by the nucleoid-associated protein H-NS, which recognizes and binds to AT-rich DNA. H-NS-mediated silencing must be countered by other DNA-binding proteins to allow expression under appropriate conditions. Some genes that can be transcribed by RNA polymerase (RNAP) associated with the alternative sigma factor σS or the housekeeping sigma factor σ70 in vitro appear to be preferentially transcribed by σS in the presence of H-NS, suggesting that σS may act as a counter-silencer. To determine whether σS directly counters H-NS-mediated silencing and whether co-regulation by H-NS accounts for the σS selectivity of certain promoters, we examined the csgBA operon, which is required for curli fimbriae expression and is known to be regulated by both H-NS and σS . Using genetics and in vitro biochemical analyses, we found that σS is not directly required for csgBA transcription, but rather up-regulates csgBA via an indirect upstream mechanism. Instead, the biofilm master regulator CsgD directly counter-silences the csgBA promoter by altering the DNA-protein complex structure to disrupt H-NS-mediated silencing in addition to directing the binding of RNAP.
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Affiliation(s)
- S L Newman
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA.,Department of Laboratory Medicine, University of Washington, Seattle, WA, USA
| | - W R Will
- Department of Microbiology, University of Washington, Seattle WA, USA
| | - S J Libby
- Department of Microbiology, University of Washington, Seattle WA, USA
| | - F C Fang
- Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.,Department of Microbiology, University of Washington, Seattle WA, USA
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