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Pérez-Vázquez M, López-Causapé C, Corral-Lugo A, McConnell MJ, Oteo-Iglesias J, Oliver A, Martín-Galiano AJ. Mutation Analysis in Regulator DNA-Binding Regions for Antimicrobial Efflux Pumps in 17,000 Pseudomonas aeruginosa Genomes. Microorganisms 2023; 11:2486. [PMID: 37894144 PMCID: PMC10609311 DOI: 10.3390/microorganisms11102486] [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: 09/07/2023] [Revised: 09/26/2023] [Accepted: 09/27/2023] [Indexed: 10/29/2023] Open
Abstract
Mutations leading to upregulation of efflux pumps can produce multiple drug resistance in the pathogen Pseudomonas aeruginosa. Changes in their DNA binding regions, i.e., palindromic operators, can compromise pump depression and subsequently enhance resistance against several antibacterials and biocides. Here, we have identified (pseudo)palindromic repeats close to promoters of genes encoding 13 core drug-efflux pumps of P. aeruginosa. This framework was applied to detect mutations in these repeats in 17,292 genomes. Eighty-nine percent of isolates carried at least one mutation. Eight binary genetic properties potentially related to expression were calculated for mutations. These included palindromicity reduction, mutation type, positioning within the repeat and DNA-bending shift. High-risk ST298, ST308 and ST357 clones commonly carried four conserved mutations while ST175 and the cystic fibrosis-linked ST649 clones showed none. Remarkably, a T-to-C transition in the fourth position of the upstream repeat for mexEF-oprN was nearly exclusive of the high-risk ST111 clone. Other mutations were associated with high-risk sublineages using sample geotemporal metadata. Moreover, 1.5% of isolates carried five or more mutations suggesting they undergo an alternative program for regulation of their effluxome. Overall, P. aeruginosa shows a wide range of operator mutations with a potential effect on efflux pump expression and antibiotic resistance.
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Affiliation(s)
- María Pérez-Vázquez
- Reference and Research Laboratory for Antibiotic Resistance and Health Care Infections, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Majadahonda, 28029 Madrid, Spain; (M.P.-V.); (J.O.-I.)
- CIBER de Enfermedades Infecciosas (CIBERINFEC), 28029 Madrid, Spain; (C.L.-C.); (A.O.)
| | - Carla López-Causapé
- CIBER de Enfermedades Infecciosas (CIBERINFEC), 28029 Madrid, Spain; (C.L.-C.); (A.O.)
- Microbiology Department-Research Institute Biomedical Islas Baleares (IdISDBa), Hospital Son Espases, 07122 Palma de Mallorca, Spain
| | - Andrés Corral-Lugo
- Intrahospital Infections Unit, National Centre for Microbiology, ISCIII, Majadahonda, 28029 Madrid, Spain;
| | - Michael J. McConnell
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA;
| | - Jesús Oteo-Iglesias
- Reference and Research Laboratory for Antibiotic Resistance and Health Care Infections, National Centre for Microbiology, Instituto de Salud Carlos III (ISCIII), Majadahonda, 28029 Madrid, Spain; (M.P.-V.); (J.O.-I.)
- CIBER de Enfermedades Infecciosas (CIBERINFEC), 28029 Madrid, Spain; (C.L.-C.); (A.O.)
| | - Antonio Oliver
- CIBER de Enfermedades Infecciosas (CIBERINFEC), 28029 Madrid, Spain; (C.L.-C.); (A.O.)
- Microbiology Department-Research Institute Biomedical Islas Baleares (IdISDBa), Hospital Son Espases, 07122 Palma de Mallorca, Spain
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2
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Curuksu JD. Spectral analysis of DNA superhelical dynamics from molecular minicircle simulations. J Chem Phys 2023; 159:105101. [PMID: 37694753 DOI: 10.1063/5.0164440] [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: 06/22/2023] [Accepted: 08/22/2023] [Indexed: 09/12/2023] Open
Abstract
Torsional and bending deformations of DNA molecules often occur in vivo and are important for biological functions. DNA "under stress" is a conformational state, which is by far the most frequent state during DNA-protein and gene regulation. In DNA minicircles of length <100 base pairs (bp), the combined effect of torsional and bending stresses can cause local unusual conformations, with certain base pair steps often absorbing most of the stress, leaving other steps close to their relaxed conformation. To better understand the superhelical dynamics of DNA under stress, molecular simulations of 94 bp minicircles with different torsional linking numbers were interpreted using Fourier analyses and principal component analyses. Sharp localized bends of nearly 90° in the helical axis were observed, which in turn decreased fluctuations of the rotational register and helped redistribute the torsional stress into writhe, i.e., superhelical turn up to 360°. In these kinked minicircles, only two-thirds of the DNA molecule bends and writhes and the remaining segment stays close to straight and preserves a conformational flexibility typical of canonical B-DNA (bending of 39° ± 17° distributed parsimoniously across 36 bp), which was confirmed and visualized by principal component analysis. These results confirm that stressed DNA molecules are highly heterogeneous along their sequence, with segments designed to locally store and release stress so that nearby segments can stay relaxed.
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Affiliation(s)
- Jeremy D Curuksu
- Amazon.com, Inc., New York, New York 10001, USA and Center for Data Science, New York University, New York, New York 10011, USA
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3
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Sun G, Yu Z, Li Q, Zhang Y, Wang M, Liu Y, Liu J, Liu L, Yu X. Mechanism of Escherichia coli Lethality Caused by Overexpression of flhDC, the Flagellar Master Regulator Genes, as Revealed by Transcriptome Analysis. Int J Mol Sci 2023; 24:14058. [PMID: 37762361 PMCID: PMC10530849 DOI: 10.3390/ijms241814058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/29/2023] Open
Abstract
The flhDC operon of Escherichia coli encodes a transcription factor that initiates flagella synthesis, elevates flagella construction and enhances cell motility, which all are energetically costly and highly regulated processes. In this study, we found that overexpression of flhDC genes from a strong regulatable pN15E6 plasmid could inhibit the growth of E. coli host cells and even eventually cause death. We used transcriptome analysis to investigate the mechanism of flhDC overexpression lethal to host bacteria. The results showed that a total of 568 differentially expressed genes (DEGs), including 378 up-regulated genes and 190 down-regulated genes were detected when the flhDC genes were over-expressed. Functional enrichment analysis results showed that the DEGs are related to a series of crucial biomolecular processes, including flagella synthesis, oxidative phosphorylation and pentose phosphate pathways, etc. We then examined, using RT-qPCR, the expression of key genes of the oxidative phosphorylation pathway at different time points after induction. Results showed that their expression increased in the early stage and decreased afterward, which was suggested to be the result of feedback on the overproduction of ROS, a strong side effect product of the elevated oxidative phosphorylation process. To further verify the level of ROS output, flhDC over-expressed bacteria cells were stained with DCHF-DA and a fluorescence signal was detected using flow cytometry. Results showed that the level of ROS output was higher in cells with over-expressed flhDC than in normal controls. Besides, we found upregulation of other genes (recN and zwf) that respond to ROS damage. This leads to the conclusion that the bacterial death led by the overexpression of flhDC genes is caused by damage from ROS overproduction, which leaked from the oxidative phosphorylation pathway.
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Affiliation(s)
- Guanglu Sun
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Zihao Yu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Qianwen Li
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Yuanxing Zhang
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Mingxiao Wang
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Yunhui Liu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Jinze Liu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Lei Liu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
| | - Xuping Yu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou 310058, China; (G.S.)
- Center for Veterinary Sciences, Zhejiang University, Hangzhou 310030, China
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4
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Natarajan AK, Ryssy J, Kuzyk A. A DNA origami-based device for investigating DNA bending proteins by transmission electron microscopy. NANOSCALE 2023; 15:3212-3218. [PMID: 36722916 DOI: 10.1039/d2nr05366g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The DNA origami technique offers precise positioning of nanoscale objects with high accuracy. This has facilitated the development of DNA origami-based functional nanomechanical devices that enable the investigation of DNA-protein interactions at the single particle level. Herein, we used the DNA origami technique to fabricate a nanoscale device for studying DNA bending proteins. For a proof of concept, we used TATA-box binding protein (TBP) to evaluate our approach. Upon binding to the TATA box, TBP causes a bend to DNA of ∼90°. Our device translates this bending into an angular change that is readily observable with a conventional transmission electron microscope (TEM). Furthermore, we investigated the roles of transcription factor II A (TF(II)A) and transcription factor II B (TF(II)B). Our results indicate that TF(II)A introduces additional bending, whereas TF(II)B does not significantly alter the TBP-DNA structure. Our approach can be readily adopted to a wide range of DNA-bending proteins and will aid the development of DNA-origami-based devices tailored for the investigation of DNA-protein interactions.
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Affiliation(s)
- Ashwin Karthick Natarajan
- Department of Neuroscience and Biomedical Engineering, Aalto University, School of Science, P.O. Box 12200, FI-00076 Aalto, Finland.
| | - Joonas Ryssy
- Department of Neuroscience and Biomedical Engineering, Aalto University, School of Science, P.O. Box 12200, FI-00076 Aalto, Finland.
| | - Anton Kuzyk
- Department of Neuroscience and Biomedical Engineering, Aalto University, School of Science, P.O. Box 12200, FI-00076 Aalto, Finland.
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5
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Casa PL, de Abreu FP, Benvenuti JL, Martinez GS, de Avila e Silva S. Beyond consensual motifs: an analysis of DNA curvature within Escherichia coli promoters. Biologia (Bratisl) 2022. [DOI: 10.1007/s11756-021-00999-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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6
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Khandelwal R, Jain D, Jaishankar J, Barman A, Srivastava P, Bisaria VS. Characterization of Zymomonas mobilis promoters that are functional in Escherichia coli. J Biosci Bioeng 2022; 133:301-308. [DOI: 10.1016/j.jbiosc.2021.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Revised: 12/19/2021] [Accepted: 12/26/2021] [Indexed: 02/08/2023]
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7
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Liu Y, Zhang L, Guo M, Chen L, Wu B, Huang H. Structural basis for anti-CRISPR repression mediated by bacterial operon proteins Aca1 and Aca2. J Biol Chem 2021; 297:101357. [PMID: 34756887 PMCID: PMC8633003 DOI: 10.1016/j.jbc.2021.101357] [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: 05/17/2021] [Revised: 10/25/2021] [Accepted: 10/25/2021] [Indexed: 12/26/2022] Open
Abstract
It has been shown that phages have evolved anti-CRISPR (Acr) proteins to inhibit host CRISPR-Cas systems. Most acr genes are located upstream of anti-CRISPR-associated (aca) genes, which is instrumental for identifying these acr genes. Thus far, eight Aca families (Aca1-Aca8) have been identified, all proteins of which share low sequence homology and bind to different target DNA sequences. Recently, Aca1 and Aca2 proteins were discovered to function as repressors by binding to acr-aca promoters, thus implying a potential anti-anti-CRISPR mechanism. However, the structural basis for the repression roles of Aca proteins is still unknown. Here, we elucidated apo-structures of Aca1 and Aca2 proteins and their complex structures with their cognate operator DNA in two model systems, the Pseudomonas phage JBD30 and the Pectobacterium carotovorum template phage ZF40. In combination with biochemical and cellular assays, our study unveils dimerization and DNA-recognition mechanisms of Aca1 and Aca2 family proteins, thus revealing the molecular basis for Aca1-and Aca2-mediated anti-CRISPR repression. Our results also shed light on understanding the repression roles of other Aca family proteins and autoregulation roles of acr-aca operons.
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Affiliation(s)
- Yanhong Liu
- School of Life Science and Technology, Harbin Institute of Technology, Harbin, China; Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen, China
| | - Linsheng Zhang
- Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen, China
| | - Maochao Guo
- Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen, China
| | - Liu Chen
- Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen, China
| | - Baixing Wu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Guangdong-Hong Kong Joint Laboratory for RNA Medicine, RNA Biomedical Institute, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
| | - Hongda Huang
- Department of Biology, School of Life Sciences, Key Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen, China.
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8
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Santiago-Frangos A, Buyukyoruk M, Wiegand T, Krishna P, Wiedenheft B. Distribution and phasing of sequence motifs that facilitate CRISPR adaptation. Curr Biol 2021; 31:3515-3524.e6. [PMID: 34174210 PMCID: PMC8552246 DOI: 10.1016/j.cub.2021.05.068] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 04/30/2021] [Accepted: 05/28/2021] [Indexed: 12/11/2022]
Abstract
CRISPR-associated proteins (Cas1 and Cas2) integrate foreign DNA at the "leader" end of CRISPR loci. Several CRISPR leader sequences are reported to contain a binding site for a DNA-bending protein called integration host factor (IHF). IHF-induced DNA bending kinks the leader of type I-E CRISPRs, recruiting an upstream sequence motif that helps dock Cas1-2 onto the first repeat of the CRISPR locus. To determine the prevalence of IHF-directed CRISPR adaptation, we analyzed 15,274 bacterial and archaeal CRISPR leaders. These experiments reveal multiple IHF binding sites and diverse upstream sequence motifs in a subset of the I-C, I-E, I-F, and II-C CRISPR leaders. We identify subtype-specific motifs and show that the phase of these motifs is critical for CRISPR adaptation. Collectively, this work clarifies the prevalence and mechanism(s) of IHF-dependent CRISPR adaptation and suggests that leader sequences and adaptation proteins may coevolve under the selective pressures of foreign genetic elements like plasmids or phages.
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Affiliation(s)
| | - Murat Buyukyoruk
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Tanner Wiegand
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Pushya Krishna
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA
| | - Blake Wiedenheft
- Department of Microbiology and Immunology, Montana State University, Bozeman, MT 59717, USA.
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9
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Zheng Y, Meng F, Zhu Z, Wei W, Sun Z, Chen J, Yu B, Lou C, Chen GQ. A tight cold-inducible switch built by coupling thermosensitive transcriptional and proteolytic regulatory parts. Nucleic Acids Res 2020; 47:e137. [PMID: 31750522 PMCID: PMC6868347 DOI: 10.1093/nar/gkz785] [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: 04/10/2019] [Revised: 07/30/2019] [Accepted: 09/04/2019] [Indexed: 12/20/2022] Open
Abstract
Natural organisms have evolved intricate regulatory mechanisms that sense and respond to fluctuating environmental temperatures in a heat- or cold-inducible fashion. Unlike dominant heat-inducible switches, very few cold-inducible genetic switches are available in either natural or engineered systems. Moreover, the available cold-inducible switches still have many shortcomings, including high leaky gene expression, small dynamic range (<10-fold) or broad transition temperature (>10°C). To address these problems, a high-performance cold-inducible switch that can tightly control target gene expression is highly desired. Here, we introduce a tight and fast cold-inducible switch that couples two evolved thermosensitive variants, TFts and TEVts, as well as an additional Mycoplasma florum Lon protease (mf-Lon) to effectively turn-off target gene expression via transcriptional and proteolytic mechanisms. We validated the function of the switch in different culture media and various Escherichia coli strains and demonstrated its tightness by regulating two morphogenetic bacterial genes and expressing three heat-unstable recombinant proteins, respectively. Moreover, the additional protease module enabled the cold-inducible switch to actively remove the pre-existing proteins in slow-growing cells. This work establishes a high-performance cold-inducible system for tight and fast control of gene expression which has great potential for basic research, as well as industrial and biomedical applications.
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Affiliation(s)
- Yang Zheng
- MOE Key Lab of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fankang Meng
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100149, China
| | - Zihui Zhu
- MOE Key Lab of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Weijia Wei
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100149, China
| | - Zhi Sun
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100149, China
| | - Jinchun Chen
- MOE Key Lab of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,MOE Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Bo Yu
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Chunbo Lou
- CAS Key Laboratory of Microbial Physiological & Metabolic Engineering and State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100149, China.,College of Life Science, University of Science and Technology of China, Hefei 230027, China
| | - Guo-Qiang Chen
- MOE Key Lab of Bioinformatics, Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.,MOE Key Laboratory of Industrial Biocatalysis, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
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10
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Reading Targeted DNA Damage in the Active Demethylation Pathway: Role of Accessory Domains of Eukaryotic AP Endonucleases and Thymine-DNA Glycosylases. J Mol Biol 2020:S0022-2836(19)30720-X. [DOI: 10.1016/j.jmb.2019.12.020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 11/24/2019] [Accepted: 12/05/2019] [Indexed: 01/07/2023]
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11
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Birkholz N, Fagerlund RD, Smith LM, Jackson SA, Fineran PC. The autoregulator Aca2 mediates anti-CRISPR repression. Nucleic Acids Res 2019; 47:9658-9665. [PMID: 31428783 PMCID: PMC6765145 DOI: 10.1093/nar/gkz721] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 08/03/2019] [Accepted: 08/06/2019] [Indexed: 12/20/2022] Open
Abstract
CRISPR-Cas systems are widespread bacterial adaptive defence mechanisms that provide protection against bacteriophages. In response, phages have evolved anti-CRISPR proteins that inactivate CRISPR-Cas systems of their hosts, enabling successful infection. Anti-CRISPR genes are frequently found in operons with genes encoding putative transcriptional regulators. The role, if any, of these anti-CRISPR-associated (aca) genes in anti-CRISPR regulation is unclear. Here, we show that Aca2, encoded by the Pectobacterium carotovorum temperate phage ZF40, is an autoregulator that represses the anti-CRISPR–aca2 operon. Aca2 is a helix-turn-helix domain protein that forms a homodimer and interacts with two inverted repeats in the anti-CRISPR promoter. The inverted repeats are similar in sequence but differ in their Aca2 affinity, and we propose that they have evolved to fine-tune, and downregulate, anti-CRISPR production at different stages of the phage life cycle. Specific, high-affinity binding of Aca2 to the first inverted repeat blocks the promoter and induces DNA bending. The second inverted repeat only contributes to repression at high Aca2 concentrations in vivo, and no DNA binding was detectable in vitro. Our investigation reveals the mechanism by which an Aca protein regulates expression of its associated anti-CRISPR.
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Affiliation(s)
- Nils Birkholz
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Robert D Fagerlund
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Leah M Smith
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Simon A Jackson
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Genetics Otago, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- Bio-Protection Research Centre, University of Otago, PO Box 56, Dunedin 9054, New Zealand
- To whom correspondence should be addressed. Tel: +64 3 479 7735;
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12
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Bazlekowa-Karaban M, Prorok P, Baconnais S, Taipakova S, Akishev Z, Zembrzuska D, Popov AV, Endutkin AV, Groisman R, Ishchenko AA, Matkarimov BT, Bissenbaev A, Le Cam E, Zharkov DO, Tudek B, Saparbaev M. Mechanism of stimulation of DNA binding of the transcription factors by human apurinic/apyrimidinic endonuclease 1, APE1. DNA Repair (Amst) 2019; 82:102698. [PMID: 31518879 DOI: 10.1016/j.dnarep.2019.102698] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 08/11/2019] [Accepted: 08/31/2019] [Indexed: 12/22/2022]
Abstract
Aerobic respiration generates reactive oxygen species (ROS), which can damage nucleic acids, proteins and lipids. A number of transcription factors (TFs) contain redox-sensitive cysteine residues at their DNA-binding sites, hence ROS-induced thiol oxidation strongly inhibits their recognition of the cognate DNA sequences. Major human apurinic/apyrimidinic (AP) endonuclease 1 (APE1/APEX1/HAP-1), referred also as a redox factor 1 (Ref-1), stimulates the DNA binding activities of the oxidized TFs such as AP-1 and NF-κB. Also, APE1 participates in the base excision repair (BER) and nucleotide incision repair (NIR) pathways to remove oxidative DNA base damage. At present, the molecular mechanism underlying the TF-stimulating/redox function of APE1 and its biological role remains disputed. Here, we provide evidence that, instead of direct cysteine reduction in TFs by APE1, APE1-catalyzed NIR and TF-stimulating activities may be based on transient cooperative binding of APE1 to DNA and induction of conformational changes in the helix. The structure of DNA duplex strongly influences NIR and TF-stimulating activities. Homologous plant AP endonucleases lacking conserved cysteine residues stimulate DNA binding of the p50 subunit of NF-κB. APE1 acts synergistically with low-molecular-weight reducing agents on TFs. Finally, APE1 stimulates DNA binding of the redox-insensitive p50-C62S mutant protein. Electron microscopy imaging of APE1 complexes with DNA revealed preferential polymerization of APE1 on the gapped and intrinsically curved DNA duplexes. Molecular modeling offers a structural explanation how full-length APE1 can oligomerize on DNA. In conclusion, we propose that DNA-directed APE1 oligomerization can be regarded as a substitute for diffusion of APE1 along the DNA contour to probe for anisotropic flexibility. APE1 oligomers exacerbate pre-existing distortions in DNA and enable both NIR activity and DNA binding by TFs regardless of their oxidation state.
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Affiliation(s)
- Milena Bazlekowa-Karaban
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale Contre le Cancer, CNRS UMR8200, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France; Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, University of Warsaw, Warsaw, Poland
| | - Paulina Prorok
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale Contre le Cancer, CNRS UMR8200, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France; Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; Institute of Human Genetics, UMR 9002, CNRS - University of Montpellier, Replication and Genome Dynamics, 141 rue de la Cardonille, 34396, Montpellier, France
| | - Sonia Baconnais
- CNRS UMR8126, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France
| | - Sabira Taipakova
- Department of Molecular Biology and Genetics, Faculty of Biology, al-Farabi Kazakh National University, 0530040, Almaty, Kazakhstan
| | - Zhiger Akishev
- Department of Molecular Biology and Genetics, Faculty of Biology, al-Farabi Kazakh National University, 0530040, Almaty, Kazakhstan
| | - Dominika Zembrzuska
- Institute of Genetics and Biotechnology, University of Warsaw, Warsaw, Poland
| | - Alexander V Popov
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Anton V Endutkin
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Regina Groisman
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale Contre le Cancer, CNRS UMR8200, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France
| | - Alexander A Ishchenko
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale Contre le Cancer, CNRS UMR8200, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France
| | - Bakhyt T Matkarimov
- National laboratory Astana, Nazarbayev University, Astana 010000, Kazakhstan
| | - Amangeldy Bissenbaev
- Department of Molecular Biology and Genetics, Faculty of Biology, al-Farabi Kazakh National University, 0530040, Almaty, Kazakhstan
| | - Eric Le Cam
- CNRS UMR8126, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France
| | - Dmitry O Zharkov
- Institute of Chemical Biology and Fundamental Medicine, SB RAS, Novosibirsk 630090, Russia; Novosibirsk State University, Novosibirsk 630090, Russia
| | - Barbara Tudek
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland; Institute of Genetics and Biotechnology, University of Warsaw, Warsaw, Poland
| | - Murat Saparbaev
- Groupe «Réparation de l'ADN», Equipe Labellisée par la Ligue Nationale Contre le Cancer, CNRS UMR8200, Université Paris-Sud, Université Paris-Saclay, Gustave Roussy Cancer Campus, F-94805 Villejuif Cedex, France.
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13
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Paulsen T, Shibata Y, Kumar P, Dillon L, Dutta A. Small extrachromosomal circular DNAs, microDNA, produce short regulatory RNAs that suppress gene expression independent of canonical promoters. Nucleic Acids Res 2019; 47:4586-4596. [PMID: 30828735 PMCID: PMC6511871 DOI: 10.1093/nar/gkz155] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/20/2019] [Accepted: 02/25/2019] [Indexed: 01/17/2023] Open
Abstract
Interest in extrachromosomal circular DNA (eccDNA) molecules has increased recently because of their widespread presence in normal cells across every species ranging from yeast to humans, their increased levels in cancer cells and their overlap with oncogenic and drug-resistant genes. However, the majority of eccDNA (microDNA) in mammalian tissues and cell lines are too small to carry protein coding genes. We have tested functional capabilities of microDNA by creating artificial microDNA molecules mimicking known microDNA sequences and have discovered that they express functional small regulatory RNA including microRNA and novel si-like RNA. MicroDNA are transcribed in vitro and in vivo independent of a canonical promoter sequence. MicroDNA that carry miRNA genes form transcripts that are processed by the endogenous RNA-interference pathway into mature miRNA molecules, which repress a luciferase reporter gene as well as endogenous mRNA targets of the miRNA. Further, microDNA that contain sequences of exons repress the endogenous gene from which the microDNA were derived through the formation of novel si-like RNA. We also show that endogenous microDNA associate with RNA polymerases subunits, POLR2H and POLR3F. Together, these results suggest that microDNA may modulate gene expression through the production of both known and novel regulatory small RNA.
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Affiliation(s)
- Teressa Paulsen
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Yoshiyuki Shibata
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Pankaj Kumar
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Laura Dillon
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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14
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Kim SH, Ganji M, Kim E, van der Torre J, Abbondanzieri E, Dekker C. DNA sequence encodes the position of DNA supercoils. eLife 2018; 7:e36557. [PMID: 30523779 PMCID: PMC6301789 DOI: 10.7554/elife.36557] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Accepted: 12/06/2018] [Indexed: 12/13/2022] Open
Abstract
The three-dimensional organization of DNA is increasingly understood to play a decisive role in vital cellular processes. Many studies focus on the role of DNA-packaging proteins, crowding, and confinement in arranging chromatin, but structural information might also be directly encoded in bare DNA itself. Here, we visualize plectonemes (extended intertwined DNA structures formed upon supercoiling) on individual DNA molecules. Remarkably, our experiments show that the DNA sequence directly encodes the structure of supercoiled DNA by pinning plectonemes at specific sequences. We develop a physical model that predicts that sequence-dependent intrinsic curvature is the key determinant of pinning strength and demonstrate this simple model provides very good agreement with the data. Analysis of several prokaryotic genomes indicates that plectonemes localize directly upstream of promoters, which we experimentally confirm for selected promotor sequences. Our findings reveal a hidden code in the genome that helps to spatially organize the chromosomal DNA.
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Affiliation(s)
- Sung Hyun Kim
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Mahipal Ganji
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Eugene Kim
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Jaco van der Torre
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Elio Abbondanzieri
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
| | - Cees Dekker
- Department of BionanoscienceKavli Institute of Nanoscience, Delft University of TechnologyDelftThe Netherlands
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15
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de la Campa AG, Ferrándiz MJ, Martín-Galiano AJ, García MT, Tirado-Vélez JM. The Transcriptome of Streptococcus pneumoniae Induced by Local and Global Changes in Supercoiling. Front Microbiol 2017; 8:1447. [PMID: 28824578 PMCID: PMC5534458 DOI: 10.3389/fmicb.2017.01447] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/17/2017] [Indexed: 01/28/2023] Open
Abstract
The bacterial chromosome is compacted in a manner optimal for DNA transactions to occur. The degree of compaction results from the level of DNA-supercoiling and the presence of nucleoid-binding proteins. DNA-supercoiling is homeostatically maintained by the opposing activities of relaxing DNA topoisomerases and negative supercoil-inducing DNA gyrase. DNA-supercoiling acts as a general cis regulator of transcription, which can be superimposed upon other types of more specific trans regulatory mechanism. Transcriptomic studies on the human pathogen Streptococcus pneumoniae, which has a relatively small genome (∼2 Mb) and few nucleoid-binding proteins, have been performed under conditions of local and global changes in supercoiling. The response to local changes induced by fluoroquinolone antibiotics, which target DNA gyrase subunit A and/or topoisomerase IV, involves an increase in oxygen radicals which reduces cell viability, while the induction of global supercoiling changes by novobiocin (a DNA gyrase subunit B inhibitor), or by seconeolitsine (a topoisomerase I inhibitor), has revealed the existence of topological domains that specifically respond to such changes. The control of DNA-supercoiling in S. pneumoniae occurs mainly via the regulation of topoisomerase gene transcription: relaxation triggers the up-regulation of gyrase and the down-regulation of topoisomerases I and IV, while hypernegative supercoiling down-regulates the expression of topoisomerase I. Relaxation affects 13% of the genome, with the majority of the genes affected located in 15 domains. Hypernegative supercoiling affects 10% of the genome, with one quarter of the genes affected located in 12 domains. However, all the above domains overlap, suggesting that the chromosome is organized into topological domains with fixed locations. Based on its response to relaxation, the pneumococcal chromosome can be said to be organized into five types of domain: up-regulated, down-regulated, position-conserved non-regulated, position-variable non-regulated, and AT-rich. The AT content is higher in the up-regulated than in the down-regulated domains. Genes within the different domains share structural and functional characteristics. It would seem that a topology-driven selection pressure has defined the chromosomal location of the metabolism, virulence and competence genes, which suggests the existence of topological rules that aim to improve bacterial fitness.
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Affiliation(s)
- Adela G de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain.,Presidencia, Consejo Superior de Investigaciones CientíficasMadrid, Spain
| | - María J Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - Antonio J Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
| | - María T García
- Departamento de Microbiología, Facultad de Ciencias Biológicas, Universidad ComplutenseMadrid, Spain
| | - Jose M Tirado-Vélez
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos IIIMadrid, Spain
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16
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Dawoud TM, Davis ML, Park SH, Kim SA, Kwon YM, Jarvis N, O’Bryan CA, Shi Z, Crandall PG, Ricke SC. The Potential Link between Thermal Resistance and Virulence in Salmonella: A Review. Front Vet Sci 2017; 4:93. [PMID: 28660201 PMCID: PMC5469892 DOI: 10.3389/fvets.2017.00093] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/01/2017] [Indexed: 12/19/2022] Open
Abstract
In some animals, the typical body temperature can be higher than humans, for example, 42°C in poultry and 40°C in rabbits which can be a potential thermal stress challenge for pathogens. Even in animals with lower body temperatures, when infection occurs, the immune system may increase body temperature to reduce the chance of survival for pathogens. However, some pathogens can still easily overcome higher body temperatures and/or rise in body temperatures through expression of stress response mechanisms. Salmonella is the causative agent of one of the most prevalent foodborne illnesses, salmonellosis, and can readily survive over a wide range of temperatures due to the efficient expression of the heat (thermal) stress response. Therefore, thermal resistance mechanisms can provide cross protection against other stresses including the non-specific host defenses found within the human body thus increasing pathogenic potential. Understanding the molecular mechanisms associated with thermal responses in Salmonella is crucial in designing and developing more effective or new treatments for reducing and eliminating infection caused by Salmonella that have survived heat stress. In this review, Salmonella thermal resistance is assessed followed by an overview of the thermal stress responses with a focus on gene regulation by sigma factors, heat shock proteins, along with the corresponding thermosensors and their association with virulence expression including a focus on a potential link between heat resistance and potential for infection.
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Affiliation(s)
- Turki M. Dawoud
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
| | - Morgan L. Davis
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Si Hong Park
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Sun Ae Kim
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Young Min Kwon
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Poultry Science, University of Arkansas, Fayetteville, AR, United States
| | - Nathan Jarvis
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Corliss A. O’Bryan
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Zhaohao Shi
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Philip G. Crandall
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
| | - Steven C. Ricke
- Cell and Molecular Biology Program, University of Arkansas, Fayetteville, AR, United States
- Center for Food Safety, University of Arkansas, Fayetteville, AR, United States
- Department of Food Science, University of Arkansas, Fayetteville, AR, United States
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17
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Mekler V, Minakhin L, Severinov K. Mechanism of duplex DNA destabilization by RNA-guided Cas9 nuclease during target interrogation. Proc Natl Acad Sci U S A 2017; 114:5443-5448. [PMID: 28484024 PMCID: PMC5448204 DOI: 10.1073/pnas.1619926114] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The prokaryotic clustered regularly interspaced short palindromic repeats (CRISPR)-associated 9 (Cas9) endonuclease cleaves double-stranded DNA sequences specified by guide RNA molecules and flanked by a protospacer adjacent motif (PAM) and is widely used for genome editing in various organisms. The RNA-programmed Cas9 locates the target site by scanning genomic DNA. We sought to elucidate the mechanism of initial DNA interrogation steps that precede the pairing of target DNA with guide RNA. Using fluorometric and biochemical assays, we studied Cas9/guide RNA complexes with model DNA substrates that mimicked early intermediates on the pathway to the final Cas9/guide RNA-DNA complex. The results show that Cas9/guide RNA binding to PAM favors separation of a few PAM-proximal protospacer base pairs allowing initial target interrogation by guide RNA. The duplex destabilization is mediated, in part, by Cas9/guide RNA affinity for unpaired segments of nontarget strand DNA close to PAM. Furthermore, our data indicate that the entry of double-stranded DNA beyond a short threshold distance from PAM into the Cas9/single-guide RNA (sgRNA) interior is hindered. We suggest that the interactions unfavorable for duplex DNA binding promote DNA bending in the PAM-proximal region during early steps of Cas9/guide RNA-DNA complex formation, thus additionally destabilizing the protospacer duplex. The mechanism that emerges from our analysis explains how the Cas9/sgRNA complex is able to locate the correct target sequence efficiently while interrogating numerous nontarget sequences associated with correct PAMs.
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Affiliation(s)
- Vladimir Mekler
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854;
| | - Leonid Minakhin
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854
| | - Konstantin Severinov
- Waksman Institute of Microbiology, Rutgers, State University of New Jersey, Piscataway, NJ 08854;
- Department of Molecular Biology and Biochemistry, Rutgers, State University of New Jersey, Piscataway, NJ 08854
- Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
- Peter the Great State Polytechnical Institute, St. Petersburg 195251, Russia
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18
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Berset Y, Merulla D, Joublin A, Hatzimanikatis V, van der Meer JR. Mechanistic Modeling of Genetic Circuits for ArsR Arsenic Regulation. ACS Synth Biol 2017; 6:862-874. [PMID: 28215088 DOI: 10.1021/acssynbio.6b00364] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Bioreporters are living cells that generate an easily measurable signal in the presence of a chemical compound. They acquire their functionality from synthetic gene circuits, the configuration of which defines the response signal and signal-to-noise ratio. Bioreporters based on the Escherichia coli ArsR system have raised significant interest for quantifying arsenic pollution, but they need to be carefully optimized to accurately work in the required low concentration range (1-10 μg arsenite L-1). To better understand the general functioning of ArsR-based genetic circuits, we developed a comprehensive mechanistic model that was empirically tested and validated in E. coli carrying different circuit configurations. The model accounts for the different elements in the circuits (proteins, DNA, chemical species), and their detailed affinities and interactions, and predicts the (fluorescent) output from the bioreporter cell as a function of arsenite concentration. The model was parametrized using existing ArsR biochemical data, and then complemented by parameter estimations from the accompanying experimental data using a scatter search algorithm. Model predictions and experimental data were largely coherent for feedback and uncoupled circuit configurations, different ArsR alleles, promoter strengths, and presence or absence of arsenic efflux in the bioreporters. Interestingly, the model predicted a particular useful circuit variant having steeper response at low arsenite concentrations, which was experimentally confirmed and may be useful as arsenic bioreporter in the field. From the extensive validation we expect the mechanistic model to further be a useful framework for detailed modeling of other synthetic circuits.
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Affiliation(s)
- Yves Berset
- Department
of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
- Laboratory
of Computational Systems Biotechnology, Ecole Polytechnique Fédérale de Lausane (EPFL), CH 1015 Lausanne, Switzerland
| | - Davide Merulla
- Department
of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Aurélie Joublin
- Department
of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Vassily Hatzimanikatis
- Laboratory
of Computational Systems Biotechnology, Ecole Polytechnique Fédérale de Lausane (EPFL), CH 1015 Lausanne, Switzerland
| | - Jan R. van der Meer
- Department
of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
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19
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Deyneko IV, Kasnitz N, Leschner S, Weiss S. Composing a Tumor Specific Bacterial Promoter. PLoS One 2016; 11:e0155338. [PMID: 27171245 PMCID: PMC4865170 DOI: 10.1371/journal.pone.0155338] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 04/27/2016] [Indexed: 12/12/2022] Open
Abstract
Systemically applied Salmonella enterica spp. have been shown to invade and colonize neoplastic tissues where it retards the growth of many tumors. This offers the possibility to use the bacteria as a vehicle for the tumor specific delivery of therapeutic molecules. Specificity of such delivery is solely depending on promoter sequences that control the production of a target molecule. We have established the functional structure of bacterial promoters that are transcriptionally active exclusively in tumor tissues after systemic application. We observed that the specific transcriptional activation is accomplished by a combination of a weak basal promoter and a strong FNR binding site. This represents a minimal set of control elements required for such activation. In natural promoters, additional DNA remodeling elements are found that alter the level of transcription quantitatively. Inefficiency of the basal promoter ensures the absence of transcription outside tumors. As a proof of concept, we compiled an artificial promoter sequence from individual motifs representing FNR and basal promoter and showed specific activation in a tumor microenvironment. Our results open possibilities for the generation of promoters with an adjusted level of expression of target proteins in particular for applications in bacterial tumor therapy.
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Affiliation(s)
- Igor V. Deyneko
- Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- * E-mail:
| | - Nadine Kasnitz
- Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sara Leschner
- Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Siegfried Weiss
- Molecular Immunology, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Institute of Immunology, Medical School Hannover, Hannover, Germany
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20
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Brunwasser-Meirom M, Pollak Y, Goldberg S, Levy L, Atar O, Amit R. Using synthetic bacterial enhancers to reveal a looping-based mechanism for quenching-like repression. Nat Commun 2016; 7:10407. [PMID: 26832446 PMCID: PMC4740811 DOI: 10.1038/ncomms10407] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 12/02/2015] [Indexed: 01/20/2023] Open
Abstract
We explore a model for 'quenching-like' repression by studying synthetic bacterial enhancers, each characterized by a different binding site architecture. To do so, we take a three-pronged approach: first, we compute the probability that a protein-bound dsDNA molecule will loop. Second, we use hundreds of synthetic enhancers to test the model's predictions in bacteria. Finally, we verify the mechanism bioinformatically in native genomes. Here we show that excluded volume effects generated by DNA-bound proteins can generate substantial quenching. Moreover, the type and extent of the regulatory effect depend strongly on the relative arrangement of the binding sites. The implications of these results are that enhancers should be insensitive to 10-11 bp insertions or deletions (INDELs) and sensitive to 5-6 bp INDELs. We test this prediction on 61 σ(54)-regulated qrr genes from the Vibrio genus and confirm the tolerance of these enhancers' sequences to the DNA's helical repeat.
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Affiliation(s)
- Michal Brunwasser-Meirom
- Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - Yaroslav Pollak
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - Sarah Goldberg
- Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - Lior Levy
- Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - Orna Atar
- Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
| | - Roee Amit
- Department of Biotechnology and Food Engineering, Technion—Israel Institute of Technology, Haifa 32000, Israel
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa 32000, Israel
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21
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Ahmed W, Menon S, Karthik PVDNB, Nagaraja V. Autoregulation of topoisomerase I expression by supercoiling sensitive transcription. Nucleic Acids Res 2015; 44:1541-52. [PMID: 26496944 PMCID: PMC4770202 DOI: 10.1093/nar/gkv1088] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 10/08/2015] [Indexed: 11/13/2022] Open
Abstract
The opposing catalytic activities of topoisomerase I (TopoI/relaxase) and DNA gyrase (supercoiling enzyme) ensure homeostatic maintenance of bacterial chromosome supercoiling. Earlier studies in Escherichia coli suggested that the alteration in DNA supercoiling affects the DNA gyrase and TopoI expression. Although, the role of DNA elements around the promoters were proposed in regulation of gyrase, the molecular mechanism of supercoiling mediated control of TopoI expression is not yet understood. Here, we describe the regulation of TopoI expression from Mycobacterium tuberculosis and Mycobacterium smegmatis by a mechanism termed Supercoiling Sensitive Transcription (SST). In both the organisms, topoI promoter(s) exhibited reduced activity in response to chromosome relaxation suggesting that SST is intrinsic to topoI promoter(s). We elucidate the role of promoter architecture and high transcriptional activity of upstream genes in topoI regulation. Analysis of the promoter(s) revealed the presence of sub-optimal spacing between the -35 and -10 elements, rendering them supercoiling sensitive. Accordingly, upon chromosome relaxation, RNA polymerase occupancy was decreased on the topoI promoter region implicating the role of DNA topology in SST of topoI. We propose that negative supercoiling induced DNA twisting/writhing align the -35 and -10 elements to facilitate the optimal transcription of topoI.
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Affiliation(s)
- Wareed Ahmed
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Shruti Menon
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | | | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
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22
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Fowler RC, Hanson ND. The OpdQ porin of Pseudomonas aeruginosa is regulated by environmental signals associated with cystic fibrosis including nitrate-induced regulation involving the NarXL two-component system. Microbiologyopen 2015; 4:967-82. [PMID: 26459101 PMCID: PMC4694141 DOI: 10.1002/mbo3.305] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/10/2015] [Accepted: 09/17/2015] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is a versatile opportunistic pathogen that causes chronic infections in immunocompromised hosts. Multiple porins modulate outer membrane permeability under various environmental conditions. The lung environment of cystic fibrosis (CF) patients is unique with changes occurring in nutrient availability, osmolarity, and oxygen content. Although P. aeruginosa gene expression is modified under these conditions, little is known about how they influence porin regulation. In this study, we evaluated the regulation of the outer membrane porin OpdQ, a member of the OprD family of porins, with regard to oxygen, nitrate, and/or NaCl levels. We demonstrated using promoter::fusion clones of P. aeruginosa PAO1 and clinical strains collected from CF patients that OpdQ was transcriptionally repressed under low oxygen but increased in the presence of nitrate. The nitrate‐induced regulation of OpdQ was found to be dependent on the transcription factor NarL via the NarXL two‐component system. In addition, NaCl‐induced osmotic stress increased OpdQ production among most of the clinical strains evaluated. In conclusion, these data identify for the first time that specific environmental cues associated with the CF microenvironment influence porin regulation, and that the nitrate‐induced regulation of OpdQ is associated with nitrate metabolism via the NarXL two‐component system of P. aeruginosa.
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Affiliation(s)
- Randal C Fowler
- Department of Medical Microbiology and Immunology, Center for Research in Anti-Infectives and Biotechnology, Creighton University School of Medicine, 2500 California Plaza, Omaha, Nebraska, 68178
| | - Nancy D Hanson
- Department of Medical Microbiology and Immunology, Center for Research in Anti-Infectives and Biotechnology, Creighton University School of Medicine, 2500 California Plaza, Omaha, Nebraska, 68178
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23
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Mutations That Stimulate flhDC Expression in Escherichia coli K-12. J Bacteriol 2015; 197:3087-96. [PMID: 26170415 DOI: 10.1128/jb.00455-15] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 07/09/2015] [Indexed: 01/01/2023] Open
Abstract
UNLABELLED Motility is a beneficial attribute that enables cells to access and explore new environments and to escape detrimental ones. The organelle of motility in Escherichia coli is the flagellum, and its production is initiated by the activating transcription factors FlhD and FlhC. The expression of these factors by the flhDC operon is highly regulated and influenced by environmental conditions. The flhDC promoter is recognized by σ(70) and is dependent on the transcriptional activator cyclic AMP (cAMP)-cAMP receptor protein complex (cAMP-CRP). A number of K-12 strains exhibit limited motility due to low expression levels of flhDC. We report here a large number of mutations that stimulate flhDC expression in such strains. They include single nucleotide changes in the -10 element of the promoter, in the promoter spacer, and in the cAMP-CRP binding region. In addition, we show that insertion sequence (IS) elements or a kanamycin gene located hundreds of base pairs upstream of the promoter can effectively enhance transcription, suggesting that the topology of a large upstream region plays a significant role in the regulation of flhDC expression. None of the mutations eliminated the requirement for cAMP-CRP for activation. However, several mutations allowed expression in the absence of the nucleoid organizing protein, H-NS, which is normally required for flhDC expression. IMPORTANCE The flhDC operon of Escherichia coli encodes transcription factors that initiate flagellar synthesis, an energetically costly process that is highly regulated. Few deregulating mutations have been reported thus far. This paper describes new single nucleotide mutations that stimulate flhDC expression, including a number that map to the promoter spacer region. In addition, this work shows that insertion sequence elements or a kanamycin gene located far upstream from the promoter or repressor binding sites also stimulate transcription, indicating a role of regional topology in the regulation of flhDC expression.
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Fernandez-López R, Ruiz R, de la Cruz F, Moncalián G. Transcription factor-based biosensors enlightened by the analyte. Front Microbiol 2015; 6:648. [PMID: 26191047 PMCID: PMC4486848 DOI: 10.3389/fmicb.2015.00648] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2015] [Accepted: 06/15/2015] [Indexed: 01/17/2023] Open
Abstract
Whole cell biosensors (WCBs) have multiple applications for environmental monitoring, detecting a wide range of pollutants. WCBs depend critically on the sensitivity and specificity of the transcription factor (TF) used to detect the analyte. We describe the mechanism of regulation and the structural and biochemical properties of TF families that are used, or could be used, for the development of environmental WCBs. Focusing on the chemical nature of the analyte, we review TFs that respond to aromatic compounds (XylS-AraC, XylR-NtrC, and LysR), metal ions (MerR, ArsR, DtxR, Fur, and NikR) or antibiotics (TetR and MarR). Analyzing the structural domains involved in DNA recognition, we highlight the similitudes in the DNA binding domains (DBDs) of these TF families. Opposite to DBDs, the wide range of analytes detected by TFs results in a diversity of structures at the effector binding domain. The modular architecture of TFs opens the possibility of engineering TFs with hybrid DNA and effector specificities. Yet, the lack of a crisp correlation between structural domains and specific functions makes this a challenging task.
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Affiliation(s)
| | | | | | - Gabriel Moncalián
- Departamento de Biología Molecular and Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria – Consejo Superior de Investigaciones CientíficasSantander, Spain
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Cho S, Cho YB, Kang TJ, Kim SC, Palsson B, Cho BK. The architecture of ArgR-DNA complexes at the genome-scale in Escherichia coli. Nucleic Acids Res 2015; 43:3079-88. [PMID: 25735747 PMCID: PMC4381063 DOI: 10.1093/nar/gkv150] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 02/13/2015] [Indexed: 01/26/2023] Open
Abstract
DNA-binding motifs that are recognized by transcription factors (TFs) have been well studied; however, challenges remain in determining the in vivo architecture of TF-DNA complexes on a genome-scale. Here, we determined the in vivo architecture of Escherichia coli arginine repressor (ArgR)-DNA complexes using high-throughput sequencing of exonuclease-treated chromatin-immunoprecipitated DNA (ChIP-exo). The ChIP-exo has a unique peak-pair pattern indicating 5′ and 3′ ends of ArgR-binding region. We identified 62 ArgR-binding loci, which were classified into three groups, comprising single, double and triple peak-pairs. Each peak-pair has a unique 93 base pair (bp)-long (±2 bp) ArgR-binding sequence containing two ARG boxes (39 bp) and residual sequences. Moreover, the three ArgR-binding modes defined by the position of the two ARG boxes indicate that DNA bends centered between the pair of ARG boxes facilitate the non-specific contacts between ArgR subunits and the residual sequences. Additionally, our approach may also reveal other fundamental structural features of TF-DNA interactions that have implications for studying genome-scale transcriptional regulatory networks.
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Affiliation(s)
- Suhyung Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Yoo-Bok Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Taek Jin Kang
- Department of Chemical and Biochemical Engineering, Dongguk University-Seoul, Seoul 100-715, Republic of Korea
| | - Sun Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
| | - Bernhard Palsson
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA Center for Biosustainability, Technical University of Denmark, Hørsholm, Denmark
| | - Byung-Kwan Cho
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea KI for the BioCentury, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea
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The effect of CbbR-binding affinity to the upstream of cbbF and cfxB on the metabolic effector in Rhodobacter sphaeroides. Curr Microbiol 2015; 70:816-20. [PMID: 25708583 DOI: 10.1007/s00284-015-0789-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 01/09/2015] [Indexed: 10/24/2022]
Abstract
Rhodobacter sphaeroides is a non-sulfur photosynthetic bacterium that possesses two cbb operons, cbb I and cbb II , encoding enzymes involved in the Calvin-Bensom-Bassham reductive pentose phosphate pathway of carbon dioxide fixation. In the present study, a number of molecules have been identified that have the ability to alter the in vivo DNA-binding properties of CbbR protein in R. sphaeroides. The CbbR-binding sites on the cbb operon in R. sphaeroides were characterized by chromatin immunoprecipitation (ChIP) assay. The ChIP assay indicated that the CbbR protein binds specifically to the upstream regions cbbF in cbb I operon and cfxB in cbb II operon. The change in the binding of CbbR to the upstream of cbbF and cfxB in the presence of RuBP, fructose 1,6-bisphosphate, NADPH, KH2PO4 was observed under anaerobic, aerobic, aerobic light-dark, and aerobic dark conditions, respectively. From these results, the role of different co-inducer molecules in influencing the interactions of CbbR with the binding site within cbb operon has been ascertained. The biosynthetic intermediates and other potential metabolic effectors have been observed to play an important role in the regulatory mechanism.
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27
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Dai Z, Guo D, Dai X, Xiong Y. Genome-wide analysis of transcription factor binding sites and their characteristic DNA structures. BMC Genomics 2015; 16 Suppl 3:S8. [PMID: 25708259 PMCID: PMC4331811 DOI: 10.1186/1471-2164-16-s3-s8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Transcription factors (TF) regulate gene expression by binding DNA regulatory regions. Transcription factor binding sites (TFBSs) are conserved not only in primary DNA sequences but also in DNA structures. However, the global relationship between TFs and their preferred DNA structures remains to be elucidated. Results In this paper, we have developed a computational method to generate a genome-wide landscape of TFs and their characteristic binding DNA structures in Saccharomyces cerevisiae. We revealed DNA structural features for different TFs. The structural conservation shows positional preference in TFBSs. Structural levels of DNA sequences are correlated with TF-DNA binding affinities. Conclusions We provided the genome-wide correspondences of TFs to DNA structures. Our findings will have implications in understanding TF regulatory mechanisms.
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Rydenfelt M, Garcia HG, Cox RS, Phillips R. The influence of promoter architectures and regulatory motifs on gene expression in Escherichia coli. PLoS One 2014; 9:e114347. [PMID: 25549361 PMCID: PMC4280137 DOI: 10.1371/journal.pone.0114347] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 11/02/2014] [Indexed: 12/31/2022] Open
Abstract
The ability to regulate gene expression is of central importance for the adaptability of living organisms to changes in their external and internal environment. At the transcriptional level, binding of transcription factors (TFs) in the promoter region can modulate the transcription rate, hence making TFs central players in gene regulation. For some model organisms, information about the locations and identities of discovered TF binding sites have been collected in continually updated databases, such as RegulonDB for the well-studied case of E. coli. In order to reveal the general principles behind the binding-site arrangement and function of these regulatory architectures we propose a random promoter architecture model that preserves the overall abundance of binding sites to identify overrepresented binding site configurations. This model is analogous to the random network model used in the study of genetic network motifs, where regulatory motifs are identified through their overrepresentation with respect to a “randomly connected” genetic network. Using our model we identify TF pairs which coregulate operons in an overrepresented fashion, or individual TFs which act at multiple binding sites per promoter by, for example, cooperative binding, DNA looping, or through multiple binding domains. We furthermore explore the relationship between promoter architecture and gene expression, using three different genome-wide protein copy number censuses. Perhaps surprisingly, we find no systematic correlation between the number of activator and repressor binding sites regulating a gene and the level of gene expression. A position-weight-matrix model used to estimate the binding affinity of RNA polymerase (RNAP) to the promoters of activated and repressed genes suggests that this lack of correlation might in part be due to differences in basal transcription levels, with repressed genes having a higher basal activity level. This quantitative catalogue relating promoter architecture and function provides a first step towards genome-wide predictive models of regulatory function.
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Affiliation(s)
- Mattias Rydenfelt
- Department of Physics, California Institute of Technology, Pasadena, CA, United States of America
- Integrative Research Institute for the Life Sciences and Institute for Theoretical Biology, Humboldt University, Berlin, Germany
| | - Hernan G. Garcia
- Joseph-Henry Laboratories of Physics, Princeton University, Princeton, NJ, United States of America
| | - Robert Sidney Cox
- Department of Chemical Science and Engineering, Kobe University, Kobe, Japan
| | - Rob Phillips
- Department of Applied Physics, California Institute of Technology, Pasadena, CA, United States of America
- Division of Biology, California Institute of Technology, Pasadena, CA, United States of America
- * E-mail:
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29
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Driessen RPC, Sitters G, Laurens N, Moolenaar GF, Wuite GJL, Goosen N, Dame RT. Effect of temperature on the intrinsic flexibility of DNA and its interaction with architectural proteins. Biochemistry 2014; 53:6430-8. [PMID: 25291500 PMCID: PMC5451147 DOI: 10.1021/bi500344j] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
![]()
The
helical structure of double-stranded DNA is destabilized by
increasing temperature. Above a critical temperature (the melting
temperature), the two strands in duplex DNA become fully separated.
Below this temperature, the structural effects are localized. Using
tethered particle motion in a temperature-controlled sample chamber,
we systematically investigated the effect of increasing temperature
on DNA structure and the interplay between this effect and protein
binding. Our measurements revealed that (1) increasing temperature
enhances DNA flexibility, effectively leading to more compact folding
of the double-stranded DNA chain, and (2) temperature differentially
affects different types of DNA-bending chromatin proteins from mesophilic
and thermophilic organisms. Thus, our findings aid in understanding
genome organization in organisms thriving at moderate as well as extreme
temperatures. Moreover, our results underscore the importance of carefully
controlling and measuring temperature in single-molecule DNA (micromanipulation)
experiments.
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Affiliation(s)
- Rosalie P C Driessen
- Molecular Genetics, Leiden Institute of Chemistry and Cell Observatory, Leiden University , 2333 CC Leiden, The Netherlands
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Ferrándiz MJ, Arnanz C, Martín-Galiano AJ, Rodríguez-Martín C, de la Campa AG. Role of global and local topology in the regulation of gene expression in Streptococcus pneumoniae. PLoS One 2014; 9:e101574. [PMID: 25019515 PMCID: PMC4096756 DOI: 10.1371/journal.pone.0101574] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/09/2014] [Indexed: 11/19/2022] Open
Abstract
The most basic level of transcription regulation in Streptococcus pneumoniae is the organization of its chromosome in topological domains. In response to drugs that caused DNA-relaxation, a global transcriptional response was observed. Several chromosomal domains were identified based on the transcriptional response of their genes: up-regulated (U), down-regulated (D), non-regulated (N), and flanking (F). We show that these distinct domains have different expression and conservation characteristics. Microarray fluorescence units under non-relaxation conditions were used as a measure of gene transcriptional level. Fluorescence units were significantly lower in F genes than in the other domains with a similar AT content. The transcriptional level of the domains categorized them was D>U>F. In addition, a comparison of 12 S. pneumoniae genome sequences showed a conservation of gene composition within U and D domains, and an extensive gene interchange in F domains. We tested the organization of chromosomal domains by measuring the relaxation-mediated transcription of eight insertions of a heterologous Ptccat cassette, two in each type of domain, showing that transcription depended on their chromosomal location. Moreover, transcription from the four promoters directing the five genes involved in supercoiling homeostasis, located either in U (gyrB), D (topA), or N (gyrA and parEC) domains was analyzed both in their chromosomal locations and in a replicating plasmid. Although expression from the chromosomal PgyrB and PtopA showed the expected domain regulation, their expression was down-regulated in the plasmid, which behaved as a D domain. However, both PparE and PgyrA carried their own regulatory signals, their topology-dependent expression being equivalent in the plasmid or in the chromosome. In PgyrA a DNA bend acted as a DNA supercoiling sensor. These results revealed that DNA topology functions as a general transcriptional regulator, superimposed upon other more specific regulatory mechanisms.
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Affiliation(s)
- María-José Ferrándiz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER Enfermedades Respiratorias, Madrid, Spain
| | - Cristina Arnanz
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER Enfermedades Respiratorias, Madrid, Spain
| | - Antonio J. Martín-Galiano
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER Enfermedades Respiratorias, Madrid, Spain
| | - Carlos Rodríguez-Martín
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER Enfermedades Respiratorias, Madrid, Spain
| | - Adela G. de la Campa
- Unidad de Genética Bacteriana, Centro Nacional de Microbiología, Instituto de Salud Carlos III and CIBER Enfermedades Respiratorias, Madrid, Spain
- Consejo Superior de Investigaciones Científicas, Madrid, Spain
- * E-mail:
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31
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A repetitive DNA element regulates expression of the Helicobacter pylori sialic acid binding adhesin by a rheostat-like mechanism. PLoS Pathog 2014; 10:e1004234. [PMID: 24991812 PMCID: PMC4081817 DOI: 10.1371/journal.ppat.1004234] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 05/21/2014] [Indexed: 12/12/2022] Open
Abstract
During persistent infection, optimal expression of bacterial factors is required to match the ever-changing host environment. The gastric pathogen Helicobacter pylori has a large set of simple sequence repeats (SSR), which constitute contingency loci. Through a slipped strand mispairing mechanism, the SSRs generate heterogeneous populations that facilitate adaptation. Here, we present a model that explains, in molecular terms, how an intergenically located T-tract, via slipped strand mispairing, operates with a rheostat-like function, to fine-tune activity of the promoter that drives expression of the sialic acid binding adhesin, SabA. Using T-tract variants, in an isogenic strain background, we show that the length of the T-tract generates multiphasic output from the sabA promoter. Consequently, this alters the H. pylori binding to sialyl-Lewis x receptors on gastric mucosa. Fragment length analysis of post-infection isolated clones shows that the T-tract length is a highly variable feature in H. pylori. This mirrors the host-pathogen interplay, where the bacterium generates a set of clones from which the best-fit phenotypes are selected in the host. In silico and functional in vitro analyzes revealed that the length of the T-tract affects the local DNA structure and thereby binding of the RNA polymerase, through shifting of the axial alignment between the core promoter and UP-like elements. We identified additional genes in H. pylori, with T- or A-tracts positioned similar to that of sabA, and show that variations in the tract length likewise acted as rheostats to modulate cognate promoter output. Thus, we propose that this generally applicable mechanism, mediated by promoter-proximal SSRs, provides an alternative mechanism for transcriptional regulation in bacteria, such as H. pylori, which possesses a limited repertoire of classical trans-acting regulatory factors.
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Cebrián R, Rodríguez-Ruano S, Martínez-Bueno M, Valdivia E, Maqueda M, Montalbán-López M. Analysis of the promoters involved in enterocin AS-48 expression. PLoS One 2014; 9:e90603. [PMID: 24594763 PMCID: PMC3942455 DOI: 10.1371/journal.pone.0090603] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 01/31/2014] [Indexed: 11/17/2022] Open
Abstract
The enterocin AS-48 is the best characterized antibacterial circular protein in prokaryotes. It is a hydrophobic and cationic bacteriocin, which is ribosomally synthesized by enterococcal cells and post-translationally cyclized by a head-to-tail peptide bond. The production of and immunity towards AS-48 depend upon the coordinated expression of ten genes organized in two operons, as-48ABC (where genes encoding enzymes with processing, secretion, and immunity functions are adjacent to the structural as-48A gene) and as-48C1DD1EFGH. The current study describes the identification of the promoters involved in AS-48 expression. Seven putative promoters have been here amplified, and separately inserted into the promoter-probe vector pTLR1, to create transcriptional fusions with the mCherry gene used as a reporter. The activity of these promoter regions was assessed measuring the expression of the fluorescent mCherry protein using the constitutive pneumococcal promoter PX as a reference. Our results revealed that only three promoters PA, P2(2) and PD1 were recognized in Enterococcus faecalis, Lactococcus lactis and Escherichia coli, in the conditions tested. The maximal fluorescence was obtained with PX in all the strains, followed by the P2(2) promoter, which level of fluorescence was 2-fold compared to PA and 4-fold compared to PD1. Analysis of putative factors influencing the promoter activity in single and double transformants in E. faecalis JH2-2 demonstrated that, in general, a better expression was achieved in presence of pAM401-81. In addition, the P2(2) promoter could be regulated in a negative fashion by genes existing in the native pMB-2 plasmid other than those of the as-48 cluster, while the pH seems to affect differently the as-48 promoter expression.
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Affiliation(s)
- Rubén Cebrián
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Sonia Rodríguez-Ruano
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Manuel Martínez-Bueno
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Eva Valdivia
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Mercedes Maqueda
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - Manuel Montalbán-López
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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Daddaoua A, Krell T, Ramos JL. Transcriptional control by two interacting regulatory proteins: identification of the PtxS binding site at PtxR. Nucleic Acids Res 2013; 41:10150-6. [PMID: 24019239 PMCID: PMC3905896 DOI: 10.1093/nar/gkt773] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The PtxS and PtxR regulators control the expression of the glucose dehydrogenase genes from the Pgad promoter in Pseudomonas aeruginosa. These regulators bind to their cognate operators, that are separated by ∼50 nt, within the promoter region and interact with each other creating a DNA-loop that prevents RNA polymerase promoter access. Binding of the 2-ketogluconate effector to PtxS caused PtxS/PtxR complex dissociation and led to the dissolution of the repression loop facilitating the entry of the RNA polymerase and enabling the transcription of the gad gene. We have identified a hydrophobic surface patch on the PtxR putative surface that was hypothesized to correspond to the binding site for PtxS. Two surface-exposed residues in this patch, V173 and W269, were replaced by alanine. Isothermal titration calorimetry assays showed that PtxS does not interact with the mutant variants of PtxR. Electrophoretic mobility shift assay and DNAase I footprinting assays proved that both regulators bind to their target operators and that failure to interact with each other prevented the formation of the DNA-loop. In vitro transcription showed that PtxS per se is sufficient to inhibit transcription from the Pgad promoter, but that affinity of PtxS for its effector is modulated by PtxR.
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Affiliation(s)
- Abdelali Daddaoua
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Estación Experimental del Zaidín, Calle Profesor Albareda 1, E-18008 Granada, Spain
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Lin MH, Fu JF, Liu ST. A repeat sequence causes competition of ColE1-type plasmids. PLoS One 2013; 8:e61668. [PMID: 23613898 PMCID: PMC3628316 DOI: 10.1371/journal.pone.0061668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 03/11/2013] [Indexed: 11/18/2022] Open
Abstract
Plasmid pSW200 from Pantoea stewartii contains 41 copies of 15-bp repeats and has a replicon that is homologous to that of ColE1. Although deleting the repeats (pSW207) does not change the copy number and stability of the plasmid. The plasmid becomes unstable and is rapidly lost from the host when a homoplasmid with the repeats (pSW201) is present. Deleting the repeats is found to reduce the transcriptional activity of RNAIp and RNAIIp by about 30%, indicating that the repeats promote the transcription of RNAI and RNAII, and how the RNAI that is synthesized by pSW201 inhibits the replication of pSW207. The immunoblot analysis herein demonstrates that RNA polymerase β subunit and σ(70) in the lysate from Escherichia coli MG1655 bind to a biotin-labeled DNA probe that contains the entire sequence of the repeat region. Electrophoretic mobility shift assay also reveals that purified RNA polymerase shifts a DNA probe that contains four copies of the repeats. These results thus obtained reveal that RNA polymerase holoenzyme binds to the repeats. The repeats also exchange RNA polymerase with RNAIp and RNAIIp in vitro, revealing the mechanism by which the transcription is promoted. This investigation elucidates a mechanism by which a plasmid prevents the invasion of an incompatible plasmid and maintains its stability in the host cell during evolution.
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Affiliation(s)
- Mei-Hui Lin
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan
| | - Jen-Fen Fu
- Department of Medical Research, Chang Gung Memorial Hospital, and Graduate Institute of Clinical Medical Sciences Taoyuan, Taiwan
| | - Shih-Tung Liu
- Department of Microbiology and Immunology, College of Medicine, Chang Gung University, Taoyuan, Taiwan
- Research Center for Pathogenic Bacteria, Chang Gung University, Taoyuan, Taiwan
- * E-mail:
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35
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Regulatory twist and synergistic role of metabolic coinducer- and response regulator-mediated CbbR-cbbI interactions in Rhodopseudomonas palustris CGA010. J Bacteriol 2013; 195:1381-8. [PMID: 23292778 DOI: 10.1128/jb.02060-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhodopseudomonas palustris assimilates CO2 by the Calvin-Benson-Bassham (CBB) reductive pentose phosphate pathway. Most genes required for a functional CBB pathway are clustered into the cbbI and cbbII operons, with the cbbI operon subject to control by a LysR transcriptional activator, CbbR, encoded by cbbR, which is divergently transcribed from the cbbLS genes (encoding form I RubisCO) of the cbbI operon. Juxtaposed between the genes encoding CbbR and CbbLS are genes that encode a three-protein two-component system (CbbRRS system) that functions to modify the ability of CbbR to regulate cbbLS expression. Previous studies indicated that the response regulators, as well as various coinducers (effectors), specifically influence CbbR-promoter interactions. In the current study, it was shown via several experimental approaches that the response regulators and coinducers act synergistically on CbbR to influence cbbLS transcription. Synergistic effects on the formation of specific CbbR-DNA complexes were quantified using surface plasmon resonance (SPR) procedures. Gel mobility shift and DNA footprint analyses further indicated structural changes in the DNA arising from the presence of response regulators and coinducer molecules binding to CbbR. Based on previous studies, and especially emphasized by the current investigation, it is clear that protein complexes influence promoter activity and the cbbLS transcription machinery.
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36
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Lim S, Lee B, Kim M, Kim D, Yoon H, Yong K, Kang DH, Ryu S. Analysis of HilC/D-dependent invF promoter expression under different culture conditions. Microb Pathog 2012; 52:359-66. [PMID: 22480973 DOI: 10.1016/j.micpath.2012.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Revised: 03/07/2012] [Accepted: 03/13/2012] [Indexed: 11/18/2022]
Abstract
In Salmonella enterica serovar Typhimurium, many of the genes required for intestinal penetration and invasion of host cells are encoded within the Salmonella pathogenicity island 1 (SPI1). The expression of invF, which is a positive transcriptional activator of SPI1, is controlled by HilA-dependent (invF-1) and HilC/D-dependent (invF-2) promoters. Transcriptional analysis of invF revealed that the invF-2 promoter (P(invF-2)) was not activated when cells were grown in standing culture conditions (which are known to induce SPI1) and that hilD mutation decreased the expression of P(invF-2) only in shaking culture conditions. In the absence of invF-1 promoter (P(invF-1)), P(invF-2) promoted InvF production and sipC expression (which is regulated by InvF) in shaking culture conditions. An analysis of the transcription patterns of plasmids harboring the lacZY reporter gene under various P(invF-2) derivatives with truncations or mutations revealed that the downstream region of the P(invF-2) transcription start site (i.e., +148 to +363) plays a role in repressing P(invF-2) in standing culture and in HilD-dependent activation of P(invF-2) in shaking culture conditions. The expression of invH overlaps with P(invF-2), but they are transcribed in opposite directions. However, invH expression did not influence P(invF-2) activity. This suggests that independent regulation of the two invF promoters allows Salmonella to respond quickly to environmental changes.
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Affiliation(s)
- Sangyong Lim
- Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185, Republic of Korea
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Further unraveling the regulatory twist by elucidating metabolic coinducer-mediated CbbR-cbbI promoter interactions in Rhodopseudomonas palustris CGA010. J Bacteriol 2012; 194:1350-60. [PMID: 22247506 DOI: 10.1128/jb.06418-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cbb(I) region of Rhodopseudomonas palustris (Rp. palustris) contains the cbbLS genes encoding form I ribulose-1,5-bisphosphate (RuBP) carboxylase oxygenase (RubisCO) along with a divergently transcribed regulator gene, cbbR. Juxtaposed between cbbR and cbbLS are the cbbRRS genes, encoding an unusual three-protein two-component (CbbRRS) system that modulates the ability of CbbR to influence cbbLS expression. The nature of the metabolic signals that Rp. palustris CbbR perceives to regulate cbbLS transcription is not known. Thus, in this study, the CbbR binding region was first mapped within the cbbLS promoter by the use of gel mobility shift assays and DNase I footprinting. In addition, potential metabolic coinducers (metabolites) were tested for their ability to alter the cbbLS promoter binding properties of CbbR. Gel mobility shift assays and surface plasmon resonance analyses together indicated that biosynthetic intermediates such as RuBP, ATP, fructose 1,6-bisphosphate, and NADPH enhanced DNA binding by CbbR. These coinducers did not yield identical CbbR-dependent DNase I footprints, indicating that the coinducers caused significant changes in DNA structure. These in vitro studies suggest that cellular signals such as fluctuating metabolite concentrations are perceived by and transduced to the cbbLS promoter via the master regulator CbbR.
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Evolutionary link between the mycobacterial plasmid pAL5000 replication protein RepB and the extracytoplasmic function family of σ factors. J Bacteriol 2012; 194:1331-41. [PMID: 22247504 DOI: 10.1128/jb.06218-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mycobacterial plasmid pAL5000 represents a family of plasmids found mostly in the Actinobacteria. It replicates using two plasmid-encoded proteins, RepA and RepB. While BLAST searches indicate that RepA is a replicase family protein, the evolutionary connection of RepB cannot be established, as no significant homologous partner (E < 10(-3)) outside the RepB family can be identified. To obtain insight into the structure-function and evolutionary connections of RepB, an investigation was undertaken using homology modeling, phylogenetic, and mutational analysis methods. The results indicate that although they are synthesized from the same operon, the phylogenetic affinities of RepA and RepB differ. Thus, the operon may have evolved through random breaking and joining events. Homology modeling predicted the presence of a three-helical helix-turn-helix domain characteristic of region 4 of extracytoplasmic function (ECF) σ factors in the C-terminal region of RepB. At the N-terminal region, there is a helical stretch, which may be distantly related to region 3 of σ factors. Mutational analysis identified two arginines indispensable for RepB activity, one each located within the C- and N-terminal conserved regions. Apart from analyzing the domain organization of the protein, the significance of the presence of a highly conserved A/T-rich element within the RepB binding site was investigated. Mutational analysis revealed that although this motif does not bind RepB, its integrity is important for efficient DNA-protein interactions and replication to occur. The present investigation unravels the possibility that RepB-like proteins and their binding sites represent ancient DNA-protein interaction modules.
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Dai Z, Dai X. Gene expression divergence is coupled to evolution of DNA structure in coding regions. PLoS Comput Biol 2011; 7:e1002275. [PMID: 22125484 PMCID: PMC3219629 DOI: 10.1371/journal.pcbi.1002275] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 10/01/2011] [Indexed: 01/17/2023] Open
Abstract
Sequence changes in coding region and regulatory region of the gene itself (cis) determine most of gene expression divergence between closely related species. But gene expression divergence between yeast species is not correlated with evolution of primary nucleotide sequence. This indicates that other factors in cis direct gene expression divergence. Here, we studied the contribution of DNA three-dimensional structural evolution as cis to gene expression divergence. We found that the evolution of DNA structure in coding regions and gene expression divergence are correlated in yeast. Similar result was also observed between Drosophila species. DNA structure is associated with the binding of chromatin remodelers and histone modifiers to DNA sequences in coding regions, which influence RNA polymerase II occupancy that controls gene expression level. We also found that genes with similar DNA structures are involved in the same biological process and function. These results reveal the previously unappreciated roles of DNA structure as cis-effects in gene expression. The unique phenotype of each organism is partly determined by gene expression. Changes in gene expression are an important source of phenotypic variation, and can be caused by changes in regulatory and coding sequences of the gene itself (cis) and changes in regulatory factors (trans). The contribution of cis regulation to gene expression divergence between closely related species is much greater than that of trans regulation. However, evolution of primary nucleotide sequences is not correlated with gene expression divergence in yeast, suggesting that other factors in cis drive gene expression divergence. Here, we found that evolution of DNA structure in coding regions is coupled to gene expression divergence in yeast. We also found that DNA structure is associated with specific gene characteristics. Genes with similar DNA structures are involved in the same biological process and function. These results demonstrate the important roles of DNA structure in directing gene expression.
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Affiliation(s)
- Zhiming Dai
- School of Information Science and Technology, Sun Yat-Sen University, Guangzhou, China
- * E-mail: (ZD); (XD)
| | - Xianhua Dai
- School of Information Science and Technology, Sun Yat-Sen University, Guangzhou, China
- * E-mail: (ZD); (XD)
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Just-in-time control of Spo0A synthesis in Bacillus subtilis by multiple regulatory mechanisms. J Bacteriol 2011; 193:6366-74. [PMID: 21949067 DOI: 10.1128/jb.06057-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The response regulator Spo0A governs multiple developmental processes in Bacillus subtilis, including most conspicuously sporulation. Spo0A is activated by phosphorylation via a multicomponent phosphorelay. Previous work has shown that the Spo0A protein is not rate limiting for sporulation. Rather, Spo0A is present at high levels in growing cells, rapidly rising to yet higher levels under sporulation-inducing conditions, suggesting that synthesis of the response regulator is subject to a just-in-time control mechanism. Transcription of spo0A is governed by a promoter switching mechanism, involving a vegetative, σ(A)-recognized promoter, P(v), and a sporulation σ(H)-recognized promoter, P(s), that is under phosphorylated Spo0A (Spo0A∼P) control. The spo0A regulatory region also contains four (including one identified in the present work) conserved elements that conform to the consensus binding site for Spo0A∼P binding sites. These are herein designated O(1), O(2), O(3), and O(4) in reverse order of their proximity to the coding sequence. Here we report that O(1) is responsible for repressing P(v) during the transition to stationary phase, that O(2) is responsible for repressing P(s) during growth, that O(3) is responsible for activating P(s) at the start of sporulation, and that O(4) is dispensable for promoter switching. We also report that Spo0A synthesis is subject to a posttranscriptional control mechanism such that translation of mRNAs originating from P(v) is impeded due to RNA secondary structure whereas mRNAs originating from P(s) are fully competent for protein synthesis. We propose that the opposing actions of O(2) and O(3) and the enhanced translatability of mRNAs originating from P(s) create a highly sensitive, self-reinforcing switch that is responsible for producing a burst of Spo0A synthesis at the start of sporulation.
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41
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Kiran JAP, Chakravarthi VP, Kumar YN, Rekha SS, Kruti SS, Bhaskar M. Comparison and correlation of Simple Sequence Repeats distribution in genomes of Brucella species. Bioinformation 2011; 6:179-82. [PMID: 21738309 PMCID: PMC3124796 DOI: 10.6026/97320630006179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 05/07/2011] [Indexed: 11/23/2022] Open
Abstract
UNLABELLED Computational genomics is one of the important tools to understand the distribution of closely related genomes including simple sequence repeats (SSRs) in an organism, which gives valuable information regarding genetic variations. The central objective of the present study was to screen the SSRs distributed in coding and non-coding regions among different human Brucella species which are involved in a range of pathological disorders. Computational analysis of the SSRs in the Brucella indicates few deviations from expected random models. Statistical analysis also reveals that tri-nucleotide SSRs are overrepresented and tetranucleotide SSRs underrepresented in Brucella genomes. From the data, it can be suggested that over expressed tri-nucleotide SSRs in genomic and coding regions might be responsible in the generation of functional variation of proteins expressed which in turn may lead to different pathogenicity, virulence determinants, stress response genes, transcription regulators and host adaptation proteins of Brucella genomes. ABBREVIATIONS SSRs - Simple Sequence Repeats, ORFs - Open Reading Frames.
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Affiliation(s)
| | | | - Yellapu Nanda Kumar
- Division of Animal Biotechnology, Department of Zoology, S. V. University, Tirupati-517502, Andhra Pradesh, India
| | - Somesula Swapna Rekha
- Division of Animal Biotechnology, Department of Zoology, S. V. University, Tirupati-517502, Andhra Pradesh, India
| | - Srinivasan Shanthi Kruti
- Division of Animal Biotechnology, Department of Zoology, S. V. University, Tirupati-517502, Andhra Pradesh, India
| | - Matcha Bhaskar
- Division of Animal Biotechnology, Department of Zoology, S. V. University, Tirupati-517502, Andhra Pradesh, India
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Bendtsen KM, Erdossy J, Csiszovszki Z, Svenningsen SL, Sneppen K, Krishna S, Semsey S. Direct and indirect effects in the regulation of overlapping promoters. Nucleic Acids Res 2011; 39:6879-85. [PMID: 21609952 PMCID: PMC3167631 DOI: 10.1093/nar/gkr390] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Optimal response to environmental stimuli often requires activation of certain genes and repression of others. Dual function regulatory proteins play a key role in the differential regulation of gene expression. While repression can be achieved by any DNA binding protein through steric occlusion of RNA polymerase in the promoter region, activation often requires a surface on the regulatory protein to contact RNAP and thus facilitate transcription initiation. RNAP itself is also a DNA binding protein, therefore it can function as a transcriptional repressor. Searching the Escherichia coli promoter database we found that ∼14% of the identified ‘forward’ promoters overlap with a promoter oriented in the opposite direction. In this article we combine a mathematical model with experimental analysis of synthetic regulatory regions to investigate interference of overlapping promoters. We find that promoter interference depends on the characteristics of overlapping promoters. The model predicts that promoter strength and interference can be regulated separately, which provides unique opportunities for regulation. Our experimental data suggest that in principle any DNA binding protein can be used for both activation and repression of promoter transcription, depending on the context. These findings can be exploited in the construction of synthetic networks.
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Affiliation(s)
- Kristian Moss Bendtsen
- CMOL, Niels Bohr Institute, Copenhagen, DK-2100, Denmark, Department of Genetics, Eotvos Lorand University, H-1117, Budapest, Hungary
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Santos-Aberturas J, Vicente CM, Guerra SM, Payero TD, Martín JF, Aparicio JF. Molecular control of polyene macrolide biosynthesis: direct binding of the regulator PimM to eight promoters of pimaricin genes and identification of binding boxes. J Biol Chem 2010; 286:9150-61. [PMID: 21187288 DOI: 10.1074/jbc.m110.182428] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Control of polyene macrolide production in Streptomyces natalensis is mediated by the transcriptional activator PimM. This regulator, which combines an N-terminal PAS domain with a C-terminal helix-turn-helix motif, is highly conserved among polyene biosynthetic gene clusters. PimM, truncated forms of the protein without the PAS domain (PimM(ΔPAS)), and forms containing just the DNA-binding domain (DBD) (PimM(DBD)) were overexpressed in Escherichia coli as GST-fused proteins. GST-PimM binds directly to eight promoters of the pimaricin cluster, as demonstrated by electrophoretic mobility shift assays. Assays with truncated forms of the protein revealed that the PAS domain does not mediate specificity or the distinct recognition of target genes, which rely on the DBD domain, but significantly reduces binding affinity up to 500-fold. Transcription start points were identified by 5'-rapid amplification of cDNA ends, and the binding regions of PimM(DBD) were investigated by DNase I protection studies. In all cases, binding took place covering the -35 hexamer box of each promoter, suggesting an interaction of PimM and RNA polymerase to cause transcription activation. Information content analysis of the 16 sequences protected in target promoters was used to deduce the structure of the PimM-binding site. This site displays dyad symmetry, spans 14 nucleotides, and adjusts to the consensus TVGGGAWWTCCCBA. Experimental validation of this binding site was performed by using synthetic DNA duplexes. Binding of PimM to the promoter region of one of the polyketide synthase genes from the Streptomyces nodosus amphotericin cluster containing the consensus binding site was also observed, thus proving the applicability of the findings reported here to other antifungal polyketides.
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Prosseda G, Mazzola A, Di Martino ML, Tielker D, Micheli G, Colonna B. A temperature-induced narrow DNA curvature range sustains the maximum activity of a bacterial promoter in vitro. Biochemistry 2010; 49:2778-85. [PMID: 20170130 DOI: 10.1021/bi902003g] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Among the molecular strategies bacteria have set up to quickly match their transcriptional program to new environments, changes in sequence-mediated DNA curvature play a crucial role. Bacterial promoters, especially those of mesophilic bacteria, are in general preceded by a curved region. The marked thermosensitivity of curved DNA stretches allows bacteria to rapidly sense outer temperature variations and affects transcription by favoring the binding of activators or repressors. Curved DNA is also able to influence the transcriptional activity of a bacterial promoter directly, without the involvement of trans-acting regulators. This study attempts to quantitatively analyze the role of DNA curvature in thermoregulated gene expression using a real-time in vitro transcription model system based on a specific fluorescence molecular beacon. By analyzing the temperature-dependent expression of a reporter gene in a construct carrying a progressively decreasing bent sequence upstream from the promoter, we show that with a decrease in temperature a narrow curvature range accounts for a significant enhancement of promoter activity. This strengthens the view that DNA curvature-mediated regulation of gene expression is likely a strategy offering fine-tuning control possibilities and that, considering the widespread presence of curved sequences upstream from bacterial promoters, it may represent one of the most primitive forms of gene regulation.
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Affiliation(s)
- Gianni Prosseda
- Istituto Pasteur Fondazione Cenci Bolognetti, Dip. Biologia Cellulare e dello Sviluppo, Sapienza Univ. Roma, via dei Sardi 70, 00185 Roma, Italy
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45
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Becker PD, Royo JL, Guzman CA. Exploitation of prokaryotic expression systems based on the salicylate-dependent control circuit encompassing nahR/P(sal)::xylS2 for biotechnological applications. Bioeng Bugs 2010; 1:244-51. [PMID: 21327056 DOI: 10.4161/bbug.1.4.11247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2009] [Revised: 01/11/2010] [Accepted: 01/12/2010] [Indexed: 12/13/2022] Open
Abstract
Expression vectors appear to be an indispensable tool for both biological studies and biotechnological applications. Controlling gene overexpression becomes a critical issue when protein production is desired. In addition to several aspects regarding toxicity or plasmid instability, tight control of gene expression is an essential factor in biotechnological processes. Thus, the search for better-controlled circuits is an important issue among biotechnologists. Traditionally, expression systems involve a single regulatory protein operating over a target promoter. However, these circuits are limited on their induction ratios (e.g., by their restriction in the maximal expression capacity, by their leakiness under non-induced conditions). Due to these limitations, regulatory cascades, which are far more efficient, are necessary for biotechnological applications. Thus, regulatory circuits with two modules operating in cascade offer a significant advantage. In this review, we describe the regulatory cascade based on two salicylate-responsive transcriptional regulators of Pseudomonas putida (nahR/P(sal)::xylS2), its properties, and contribution to a tighter control over heterologous gene expression in different applications.Nowadays, heterologous expression has been proven to be an indispensable tool for tackling basic biological questions, as well as for developing biotechnological applications. As the nature of the protein of interest becomes more complex, biotechnologists find that a tight control of gene expression is a key factor which conditions the success of the downstream purification process, as well as the interpretation of the results in other type of studies. Fortunately, different expression systems can be found in the market, each of them with their own pros and cons. In this review we discuss the exploitation of prokaryotic expression systems based on a promising expression system, the salicylate-dependent control circuit encompassing nahR/P(sal)::xylS2, as well as some of the improvements that have been done on this system to exploit it more efficiently in the context of both biotechnological applications and basic research.
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Affiliation(s)
- Pablo D Becker
- Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany
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46
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Oscillations in supercoiling drive circadian gene expression in cyanobacteria. Proc Natl Acad Sci U S A 2009; 106:22564-8. [PMID: 20018699 DOI: 10.1073/pnas.0912673106] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The cyanobacterium Synechococcus elongatus PCC 7942 exhibits oscillations in mRNA transcript abundance with 24-h periodicity under continuous light conditions. The mechanism underlying these oscillations remains elusive--neither cis nor trans-factors controlling circadian gene expression phase have been identified. Here, we show that the topological status of the chromosome is highly correlated with circadian gene expression state. We also demonstrate that DNA sequence characteristics of genes that appear monotonically activated and monotonically repressed by chromosomal relaxation during the circadian cycle are similar to those of supercoiling-responsive genes in Escherichia coli. Furthermore, perturbation of superhelical status within the physiological range elicits global changes in gene expression similar to those that occur during the normal circadian cycle.
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Kobori S, Ko Y, Kato M. A target site for spontaneous insertion of IS10 element in pUC19 DNA located within intrinsically bent DNA. Open Microbiol J 2009; 3:146-50. [PMID: 19812719 PMCID: PMC2758499 DOI: 10.2174/1874285800903010146] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 08/25/2009] [Accepted: 08/27/2009] [Indexed: 11/22/2022] Open
Abstract
Residual insertion sequence elements (IS elements) in Escherichia coli strains that are commonly used for DNA cloning are known to cause cloning artifacts by transposing themselves into the recombinant DNA fragments. In such cases, chance insertion of IS elements may occur at integration sites in the cloning targets, which in the case of the IS10 element is a 9-bp consensus sequence. We report here that the integration of IS10-related DNA sequences into the pUC19 cloning vector and its derivative occurred with considerable frequency in E. coli strains JM107 and DH10B, with duplication of a 9-bp segment (TCTAAAGTA). Notably, native polyacrylamide gel electrophoresis revealed that intrinsically bent DNA flanks the insertion site.
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Affiliation(s)
- Shungo Kobori
- Department of Biological Science, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuencho, Sakai 599-8531, Japan
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Nov Klaiman T, Hosid S, Bolshoy A. Upstream curved sequences in E. coli are related to the regulation of transcription initiation. Comput Biol Chem 2009; 33:275-82. [PMID: 19646927 DOI: 10.1016/j.compbiolchem.2009.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 06/17/2009] [Indexed: 01/03/2023]
Abstract
The advancement in Escherichia coli genome research has made the information regarding transcription start sites of many genes available. A study relying on the availability of transcription start locations was performed. The first question addressed was what an average DNA curvature profile upstream of genes would look like when these genes are aligned by transcription start sites in comparison to alignment by translation start sites. Since it was hypothesized that curvature plays a role in transcription regulation, the expectation was that curvature measurements relative to transcription starts, rather than translation, should strengthen the signal. Our study justified this expectation. The second question aimed to clarify the relation between DNA curvature and promoter strength. Through clustering based on DNA curvature profiles along promoter regions, a strong positive correlation between the promoter strength and the curved DNA was found. The third question dealt with dinucleotide periodicity in E. coli to see whether a periodicity pattern specific to promoter regions exists. Such unknown pattern might shed new light on transcription regulation mechanisms in E. coli. A sequence periodicity of about 11 bp is characteristic to the whole E. coli genome, and is especially well-expressed in intergenic regions. Here it was shown that regions of the size of about 100-150 bp centered 70-100 bp upstream to transcription starts carry hidden periodicity with a period of about 10.3 bp.
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Affiliation(s)
- Tamar Nov Klaiman
- Department of Evolutionary and Environmental Biology, University of Haifa, Haifa 31905, Israel
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Moscoso M, García E. Transcriptional regulation of the capsular polysaccharide biosynthesis locus of streptococcus pneumoniae: a bioinformatic analysis. DNA Res 2009; 16:177-86. [PMID: 19429668 PMCID: PMC2695774 DOI: 10.1093/dnares/dsp007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The polysaccharide capsule of Streptococcus pneumoniae is the main virulence factor, which makes the bacterium resistant to phagocytosis. Expression of capsular polysaccharide must be adjusted at different stages of pneumococcal infection, thus, their transcriptional regulation appears to be crucial. To get insight into the existence of regulatory mechanisms common to most serotypes, a bioinformatic analysis of the DNA region located upstream of the capsular locus was performed. With the exception of serotype 37, the capsular locus is located between dexB and aliA on the pneumococcal chromosome. Up to 26 different sequence organizations were found among pneumococci synthesizing their capsule through a Wzy-polymerase-dependent mechanism, mostly varying according to the presence/absence of distinct insertion elements. As a consequence, only ∼250 bp (including a 107 bp RUP_A element) was conserved in 86 sequences, although only a short (ca. 87 bp) region located immediately upstream of cpsA was strictly conserved in all the sequences analyzed. An exhaustive search for possible operator sequences was done. Interestingly, although the promoter region of serotype 3 isolates completely differs from that of other serotypes, most of the proteins proposed to regulate transcription in serotype 3 pneumococci were also predicted to function as possible regulators in non-serotype 3 S. pneumoniae isolates.
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Affiliation(s)
- Miriam Moscoso
- Centro de Investigaciones Biológicas, (CSIC) and CIBER de Enfermedades Respiratorias, Ramiro de Maeztu, Madrid 9 28040, Spain
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Abstract
Enterohemorrhagic Escherichia coli serotype O157:H7 is a pathotype of diarrheagenic E. coli that produces one or more Shiga toxins, forms a characteristic histopathology described as attaching and effacing lesions, and possesses the large virulence plasmid pO157. The bacterium is recognized worldwide, especially in developed countries, as an emerging food-borne bacterial pathogen, which causes disease in humans and in some animals. Healthy cattle are the principal and natural reservoir of E. coli O157:H7, and most disease outbreaks are, therefore, due to consumption of fecally contaminated bovine foods or dairy products. In this review, we provide a general overview of E. coli O157:H7 infection, especially focusing on the bacterial characteristics rather than on the host responses during infection.
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Affiliation(s)
- Jang W Yoon
- Division of Molecular and Life Science, Hanyang University, Ansan 426-791, Korea
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