1
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Bean EL, Smith JL, Grossman AD. Identification of insertion sites for the integrative and conjugative element Tn916 in the Bacillus subtilis chromosome. PLoS One 2025; 20:e0318964. [PMID: 40378350 PMCID: PMC12084037 DOI: 10.1371/journal.pone.0318964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2025] [Accepted: 04/14/2025] [Indexed: 05/18/2025] Open
Abstract
Integrative and conjugative elements (ICEs) are found in many bacterial species and are mediators of horizontal gene transfer. Tn916 is an ICE found in several Gram-positive genera, including Enterococcus, Staphylococcus, Streptococcus, and Clostridioides (previously Clostridium). In contrast to the many ICEs that preferentially integrate into a single site, Tn916 can integrate into many sites in the host chromosome. The consensus integration motif for Tn916, based on analyses of approximately 200 independent insertions, is an approximately 16 bp AT-rich sequence. Here, we describe the identification and mapping of approximately 105 independent Tn916 insertions in the Bacillus subtilis chromosome. The insertions were distributed between 1,554 chromosomal sites, and approximately 99% of the insertions were in 303 sites and 65% were in only ten sites. One region, between ykuC and ykyB (kre), was a 'hotspot' for integration with ~22% of the insertions in that single location. In almost all of the top 99% of sites, Tn916 was found with similar frequencies in both orientations relative to the chromosome and relative to the direction of transcription, with a few notable exceptions. Using the sequences of all insertion regions, we determined a consensus motif which is similar to that previously identified for C. difficile. The insertion sites are largely AT-rich, and some sites overlap with regions bound by the nucleoid-associated protein Rok, a functional analog of H-NS of Gram-negative bacteria. Rok functions as a negative regulator of at least some horizontally acquired genes. We found that the presence or absence of Rok had little or no effect on insertion site specificity of Tn916.
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Affiliation(s)
- Emily L. Bean
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA.
| | - Janet L. Smith
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA.
| | - Alan D. Grossman
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA.
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2
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Baptista ISC, Dash S, Arsh AM, Kandavalli V, Scandolo CM, Sanders BC, Ribeiro AS. Bimodality in E. coli gene expression: Sources and robustness to genome-wide stresses. PLoS Comput Biol 2025; 21:e1012817. [PMID: 39946496 PMCID: PMC11825099 DOI: 10.1371/journal.pcbi.1012817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2024] [Accepted: 01/22/2025] [Indexed: 02/17/2025] Open
Abstract
Bacteria evolved genes whose single-cell distributions of expression levels are broad, or even bimodal. Evidence suggests that they might enhance phenotypic diversity for coping with fluctuating environments. We identified seven genes in E. coli with bimodal (low and high) single-cell expression levels under standard growth conditions and studied how their dynamics are modified by environmental and antibiotic stresses known to target gene expression. We found that all genes lose bimodality under some, but not under all, stresses. Also, bimodality can reemerge upon cells returning to standard conditions, which suggests that the genes can switch often between high and low expression rates. As such, these genes could become valuable components of future multi-stable synthetic circuits. Next, we proposed models of bimodal transcription dynamics with realistic parameter values, able to mimic the outcome of the perturbations studied. We explored several models' tunability and boundaries of parameter values, beyond which it shifts to unimodal dynamics. From the model results, we predict that bimodality is robust, and yet tunable, not only by RNA and protein degradation rates, but also by the fraction of time that promoters remain unavailable for new transcription events. Finally, we show evidence that, although the empirical expression levels are influenced by many factors, the bimodality emerges during transcription initiation, at the promoter regions and, thus, may be evolvable and adaptable.
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Affiliation(s)
- Ines S. C. Baptista
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Suchintak Dash
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Amir M. Arsh
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Vinodh Kandavalli
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Carlo Maria Scandolo
- Department of Mathematics & Statistics, University of Calgary, Calgary, Canada
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Canada
| | - Barry C. Sanders
- Institute for Quantum Science and Technology, University of Calgary, Calgary, Canada
| | - Andre S. Ribeiro
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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3
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Hong L, Zhang Z, Wang Z, Yu X, Zhang J. Phase separation provides a mechanism to drive phenotype switching. Phys Rev E 2024; 109:064414. [PMID: 39021038 DOI: 10.1103/physreve.109.064414] [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: 03/18/2024] [Accepted: 06/05/2024] [Indexed: 07/20/2024]
Abstract
Phenotypic switching plays a crucial role in cell fate determination across various organisms. Recent experimental findings highlight the significance of protein compartmentalization via liquid-liquid phase separation in influencing such decisions. However, the precise mechanism through which phase separation regulates phenotypic switching remains elusive. To investigate this, we established a mathematical model that couples a phase separation process and a gene expression process with feedback. We used the chemical master equation theory and mean-field approximation to study the effects of phase separation on the gene expression products. We found that phase separation can cause bistability and bimodality. Furthermore, phase separation can control the bistable properties of the system, such as bifurcation points and bistable ranges. On the other hand, in stochastic dynamics, the droplet phase exhibits double peaks within a more extensive phase separation threshold range than the dilute phase, indicating the pivotal role of the droplet phase in cell fate decisions. These findings propose an alternative mechanism that influences cell fate decisions through the phase separation process. As phase separation is increasingly discovered in gene regulatory networks, related modeling research can help build biomolecular systems with desired properties and offer insights into explaining cell fate decisions.
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4
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Lawaetz AC, Cowley LA, Denham EL. Genome-wide annotation of transcript boundaries using bacterial Rend-seq datasets. Microb Genom 2024; 10. [PMID: 38668652 DOI: 10.1099/mgen.0.001239] [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] [Indexed: 05/16/2024] Open
Abstract
Accurate annotation to single-nucleotide resolution of the transcribed regions in genomes is key to optimally analyse RNA-seq data, understand regulatory events and for the design of experiments. However, currently most genome annotations provided by GenBank generally lack information about untranslated regions. Additionally, information regarding genomic locations of non-coding RNAs, such as sRNAs, or anti-sense RNAs is frequently missing. To provide such information, diverse RNA-seq technologies, such as Rend-seq, have been developed and applied to many bacterial species. However, incorporating this vast amount of information into annotation files has been limited and is bioinformatically challenging, resulting in UTRs and other non-coding elements being overlooked or misrepresented. To overcome this problem, we present pyRAP (python Rend-seq Annotation Pipeline), a software package that analyses Rend-seq datasets to accurately resolve transcript boundaries genome-wide. We report the use of pyRAP to find novel transcripts, transcript isoforms, and RNase-dependent sRNA processing events. In Bacillus subtilis we uncovered 63 novel transcripts and provide genomic coordinates with single-nucleotide resolution for 2218 5'UTRs, 1864 3'UTRs and 161 non-coding RNAs. In Escherichia coli, we report 117 novel transcripts, 2429 5'UTRs, 1619 3'UTRs and 91 non-coding RNAs, and in Staphylococcus aureus, 16 novel transcripts, 664 5'UTRs, 696 3'UTRs, and 81 non-coding RNAs. Finally, we use pyRAP to produce updated annotation files for B. subtilis 168, E. coli K-12 MG1655, and S. aureus 8325 for use in the wider microbial genomics research community.
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Affiliation(s)
- Andreas C Lawaetz
- Life Sciences Department, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Lauren A Cowley
- Life Sciences Department, University of Bath, Claverton Down, Bath, BA2 7AY, UK
- Milner Centre for Evolution, Life Sciences Department, University of Bath, Claverton Down, Bath, BA2 7AY, UK
| | - Emma L Denham
- Life Sciences Department, University of Bath, Claverton Down, Bath, BA2 7AY, UK
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5
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Morreale FE, Kleine S, Leodolter J, Junker S, Hoi DM, Ovchinnikov S, Okun A, Kley J, Kurzbauer R, Junk L, Guha S, Podlesainski D, Kazmaier U, Boehmelt G, Weinstabl H, Rumpel K, Schmiedel VM, Hartl M, Haselbach D, Meinhart A, Kaiser M, Clausen T. BacPROTACs mediate targeted protein degradation in bacteria. Cell 2022; 185:2338-2353.e18. [PMID: 35662409 PMCID: PMC9240326 DOI: 10.1016/j.cell.2022.05.009] [Citation(s) in RCA: 86] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 03/15/2022] [Accepted: 05/10/2022] [Indexed: 12/14/2022]
Abstract
Hijacking the cellular protein degradation system offers unique opportunities for drug discovery, as exemplified by proteolysis-targeting chimeras. Despite their great promise for medical chemistry, so far, it has not been possible to reprogram the bacterial degradation machinery to interfere with microbial infections. Here, we develop small-molecule degraders, so-called BacPROTACs, that bind to the substrate receptor of the ClpC:ClpP protease, priming neo-substrates for degradation. In addition to their targeting function, BacPROTACs activate ClpC, transforming the resting unfoldase into its functional state. The induced higher-order oligomer was visualized by cryo-EM analysis, providing a structural snapshot of activated ClpC unfolding a protein substrate. Finally, drug susceptibility and degradation assays performed in mycobacteria demonstrate in vivo activity of BacPROTACs, allowing selective targeting of endogenous proteins via fusion to an established degron. In addition to guiding antibiotic discovery, the BacPROTAC technology presents a versatile research tool enabling the inducible degradation of bacterial proteins.
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Affiliation(s)
- Francesca E Morreale
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Stefan Kleine
- University of Duisburg-Essen, Center of Medical Biotechnology, Faculty of Biology, 45141 Essen, Germany
| | - Julia Leodolter
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Sabryna Junker
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - David M Hoi
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Stepan Ovchinnikov
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Anastasia Okun
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Juliane Kley
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Robert Kurzbauer
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Lukas Junk
- Saarland University, Organic Chemistry I, 66123 Saarbrücken, Germany
| | - Somraj Guha
- Saarland University, Organic Chemistry I, 66123 Saarbrücken, Germany
| | - David Podlesainski
- University of Duisburg-Essen, Center of Medical Biotechnology, Faculty of Biology, 45141 Essen, Germany
| | - Uli Kazmaier
- Saarland University, Organic Chemistry I, 66123 Saarbrücken, Germany
| | - Guido Boehmelt
- Boehringer Ingelheim RCV GmbH & Co KG, 1120 Vienna, Austria
| | | | - Klaus Rumpel
- Boehringer Ingelheim RCV GmbH & Co KG, 1120 Vienna, Austria
| | | | - Markus Hartl
- Max Perutz Laboratories, Vienna Biocenter, 1030 Vienna, Austria
| | - David Haselbach
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Anton Meinhart
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria
| | - Markus Kaiser
- University of Duisburg-Essen, Center of Medical Biotechnology, Faculty of Biology, 45141 Essen, Germany.
| | - Tim Clausen
- Research Institute of Molecular Pathology, Vienna Biocenter, 1030 Vienna, Austria; Medical University of Vienna, 1030 Vienna, Austria.
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6
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Pi H, Weiss A, Laut CL, Grunenwald CM, Lin HK, Yi XI, Stauff DL, Skaar EP. An RNA-binding protein acts as a major post-transcriptional modulator in Bacillus anthracis. Nat Commun 2022; 13:1491. [PMID: 35314695 PMCID: PMC8938561 DOI: 10.1038/s41467-022-29209-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 03/01/2022] [Indexed: 12/28/2022] Open
Abstract
HitRS is a two-component system that responds to cell envelope damage in the human pathogen Bacillus anthracis. Here we identify an RNA-binding protein, KrrA, that regulates HitRS function by modulating the stability of the hitRS mRNA. In addition to hitRS, KrrA binds to over 70 RNAs and, directly or indirectly, affects the expression of over 150 genes involved in multiple processes, including genetic competence, sporulation, RNA turnover, DNA repair, transport, and cellular metabolism. KrrA does not exhibit detectable nuclease activity in vitro, and thus the mechanism by which it modulates mRNA stability remains unclear.
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Affiliation(s)
- Hualiang Pi
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Andy Weiss
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Clare L Laut
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Caroline M Grunenwald
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA
| | - Hannah K Lin
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Xinjie I Yi
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Devin L Stauff
- Department of Biology, Grove City College, Grove City, PA, USA
| | - Eric P Skaar
- Department of Pathology, Microbiology, & Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University, Nashville, TN, USA.
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7
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Deng A, Sun Z, Wang T, Cui D, Li L, Liu S, Huang F, Wen T. Simultaneous Multiplex Genome Engineering via Accelerated Natural Transformation in Bacillus subtilis. Front Microbiol 2021; 12:714449. [PMID: 34484154 PMCID: PMC8416114 DOI: 10.3389/fmicb.2021.714449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/23/2021] [Indexed: 11/13/2022] Open
Abstract
Multiplex engineering at the scale of whole genomes has become increasingly important for synthetic biology and biotechnology applications. Although several methods have been reported for engineering microbe genomes, their use is limited by their complex procedures using multi-cycle transformations. Natural transformation, involving in species evolution by horizontal gene transfer in many organisms, indicates its potential as a genetic tool. Here, we aimed to develop simultaneous multiplex genome engineering (SMGE) for the simple, rapid, and efficient design of bacterial genomes via one-step of natural transformation in Bacillus subtilis. The transformed DNA, competency factors, and recombinases were adapted to improved co-editing frequencies above 27-fold. Single to octuplet variants with genetic diversity were simultaneously generated using all-in-one vectors harboring multi-gene cassettes. To demonstrate its potential application, the tyrosine biosynthesis pathway was further optimized for producing commercially important resveratrol by high-throughput screening of variant pool in B. subtilis. SMGE represents an accelerated evolution platform that generates diverse multiplex mutations for large-scale genetic engineering and synthetic biology in B. subtilis.
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Affiliation(s)
- Aihua Deng
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Zhaopeng Sun
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Tiantian Wang
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Di Cui
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Lai Li
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Shuwen Liu
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,China Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing, China
| | - Fei Huang
- Zenbio Biotech Co., Ltd., Chengdu, China
| | - Tingyi Wen
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,China Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
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8
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Benda M, Schulz LM, Stülke J, Rismondo J. Influence of the ABC Transporter YtrBCDEF of Bacillus subtilis on Competence, Biofilm Formation and Cell Wall Thickness. Front Microbiol 2021; 12:587035. [PMID: 33897624 PMCID: PMC8060467 DOI: 10.3389/fmicb.2021.587035] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Bacillus subtilis develops genetic competence for the uptake of foreign DNA when cells enter stationary phase and a high cell density is reached. These signals are integrated by the competence transcription factor ComK, which is subject to transcriptional, post-transcriptional and post-translational regulation. Many proteins are involved in the development of competence, both to control ComK activity and to mediate DNA uptake. However, for many proteins, the precise function they play in competence development is unknown. In this study, we assessed whether proteins required for genetic transformation play a role in the activation of ComK or rather act downstream of competence gene expression. While these possibilities could be distinguished for most of the tested factors, we assume that two proteins, PNPase and the transcription factor YtrA, are required both for full ComK activity and for the downstream processes of DNA uptake and integration. Further analyses of the role of the transcription factor YtrA for the competence development revealed that the overexpression of the YtrBCDEF ABC transporter in the ytrA mutant causes the loss of genetic competence. Moreover, overexpression of this ABC transporter also affects biofilm formation. Since the ytrGABCDEF operon is naturally induced by cell wall-targeting antibiotics, we tested the cell wall properties upon overexpression of the ABC transporter and observed an increased thickness of the cell wall. The composition and properties of the cell wall are important for competence development and biofilm formation, suggesting that the observed phenotypes are the result of the increased cell wall thickness as an outcome of YtrBCDEF overexpression.
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Affiliation(s)
- Martin Benda
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany
| | - Lisa Maria Schulz
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany
| | - Jeanine Rismondo
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany
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9
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Different resource allocation in a Bacillus subtilis population displaying bimodal motility. J Bacteriol 2021; 203:e0003721. [PMID: 33782055 DOI: 10.1128/jb.00037-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
To cope with sudden changes in their environment, bacteria can use a bet-hedging strategy by dividing the population into cells with different properties. This so-called bimodal or bistable cellular differentiation is generally controlled by positive feedback regulation of transcriptional activators. Due to the continuous increase in cell volume, it is difficult for these activators to reach an activation threshold concentration when cells are growing exponentially. This is one reason why bimodal differentiation is primarily observed from the onset of the stationary phase when exponential growth ceases. An exception is the bimodal induction of motility in Bacillus subtilis, which occurs early during exponential growth. Several mechanisms have been put forward to explain this, including double negative-feedback regulation and the stability of the mRNA molecules involved. In this study, we used fluorescence-assisted cell sorting to compare the transcriptome of motile and non-motile cells and noted that expression of ribosomal genes is lower in motile cells. This was confirmed using an unstable GFP reporter fused to the strong ribosomal rpsD promoter. We propose that the reduction in ribosomal gene expression in motile cells is the result of a diversion of cellular resources to the synthesis of the chemotaxis and motility systems. In agreement, single-cell microscopic analysis showed that motile cells are slightly shorter than non-motile cells, an indication of slower growth. We speculate that this growth rate reduction can contribute to the bimodal induction of motility during exponential growth.IMPORTANCETo cope with sudden environmental changes, bacteria can use a bet-hedging strategy and generate different types of cells within a population, so called bimodal differentiation. For example, a Bacillus subtilis culture can contain both motile and non-motile cells. In this study we compared the gene expression between motile and non-motile cells. It appeared that motile cells express less ribosomes. To confirm this, we constructed a ribosomal promoter fusion that enabled us to measure expression of this promoter in individual cells. This reporter fusion confirmed our initial finding. The re-allocation of cellular resources from ribosome synthesis towards synthesis of the motility apparatus results in a reduction in growth. Interestingly, this growth reduction has been shown to stimulate bimodal differentiation.
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10
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Silale A, Lea SM, Berks BC. The DNA transporter ComEC has metal-dependent nuclease activity that is important for natural transformation. Mol Microbiol 2021; 116:416-426. [PMID: 33772889 PMCID: PMC8579336 DOI: 10.1111/mmi.14720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 12/25/2022]
Abstract
In the process of natural transformation bacteria import extracellular DNA molecules for integration into their genome. One strand of the incoming DNA molecule is degraded, whereas the remaining strand is transported across the cytoplasmic membrane. The DNA transport channel is provided by the protein ComEC. Many ComEC proteins have an extracellular C-terminal domain (CTD) with homology to the metallo-β-lactamase fold. Here we show that this CTD binds Mn2+ ions and exhibits Mn2+ -dependent phosphodiesterase and nuclease activities. Inactivation of the enzymatic activity of the CTD severely inhibits natural transformation in Bacillus subtilis. These data suggest that the ComEC CTD is a nuclease responsible for degrading the nontransforming DNA strand during natural transformation and that this process is important for efficient DNA import.
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Affiliation(s)
- Augustinas Silale
- Department of Biochemistry, University of Oxford, Oxford, UK.,Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Ben C Berks
- Department of Biochemistry, University of Oxford, Oxford, UK
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11
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Likhoshvai VA, Golubyatnikov VP, Khlebodarova TM. Limit cycles in models of circular gene networks regulated by negative feedback loops. BMC Bioinformatics 2020; 21:255. [PMID: 32921311 PMCID: PMC7488683 DOI: 10.1186/s12859-020-03598-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 06/10/2020] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND The regulatory feedback loops that present in structural and functional organization of molecular-genetic systems and the phenomenon of the regulatory signal delay, a time period between the moment of signal reception and its implementation, provide natural conditions for complicated dynamic regimes in these systems. The delay phenomenon at the intracellular level is a consequence of the matrix principle of data transmission, implemented through the rather complex processes of transcription and translation.However, the rules of the influence of system structure on system dynamics are not clearly understood. Knowledge of these rules is particularly important for construction of synthetic gene networks with predetermined properties. RESULTS We study dynamical properties of models of simplest circular gene networks regulated by negative feedback mechanisms. We have shown existence and stability of oscillating trajectories (cycles) in these models. Two algorithms of construction and localization of these cycles have been proposed. For one of these models, we have solved an inverse problem of parameters identification. CONCLUSIONS The modeling results demonstrate that non-stationary dynamics in the models of circular gene networks with negative feedback loops is achieved by a high degree of non-linearity of the mechanism of the autorepressor influence on its own expression, by the presence of regulatory signal delay, the value of which must exceed a certain critical value, and transcription/translation should be initiated from a sufficiently strong promoter/Shine-Dalgarno site. We believe that the identified patterns are key elements of the oscillating construction design.
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Affiliation(s)
- Vitaly A Likhoshvai
- Department of Systems Biology, Institute of Cytology and Genetics, Siberian Branch RAS, Novosibirsk, Russia
| | - Vladimir P Golubyatnikov
- Laboratory of Inverse Problems of Mathematical Physics, Sobolev Institute of Mathematics Siberian Branch RAS, Novosibirsk, Russia.
- Novosibirsk State University, Novosibirsk, Russia.
| | - Tamara M Khlebodarova
- Department of Systems Biology, Institute of Cytology and Genetics, Siberian Branch RAS, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
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12
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Boonstra M, Schaffer M, Sousa J, Morawska L, Holsappel S, Hildebrandt P, Sappa PK, Rath H, de Jong A, Lalk M, Mäder U, Völker U, Kuipers OP. Analyses of competent and non-competent subpopulations of Bacillus subtilis reveal yhfW, yhxC and ncRNAs as novel players in competence. Environ Microbiol 2020; 22:2312-2328. [PMID: 32249531 PMCID: PMC7317962 DOI: 10.1111/1462-2920.15005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Accepted: 03/29/2020] [Indexed: 11/28/2022]
Abstract
Upon competence-inducing nutrient-limited conditions, only part of the Bacillus subtilis population becomes competent. Here, we separated the two subpopulations by fluorescence-assisted cell sorting (FACS). Using RNA-seq, we confirmed the previously described ComK regulon. We also found for the first time significantly downregulated genes in the competent subpopulation. The downregulated genes are not under direct control by ComK but have higher levels of corresponding antisense RNAs in the competent subpopulation. During competence, cell division and replication are halted. By investigating the proteome during competence, we found higher levels of the regulators of cell division, MinD and Noc. The exonucleases SbcC and SbcD were also primarily regulated at the post-transcriptional level. In the competent subpopulation, yhfW was newly identified as being highly upregulated. Its absence reduces the expression of comG, and has a modest, but statistically significant effect on the expression of comK. Although expression of yhfW is higher in the competent subpopulation, no ComK-binding site is present in its promoter region. Mutants of yhfW have a small but significant defect in transformation. Metabolomic analyses revealed significant reductions in tricarboxylic acid (TCA) cycle metabolites and several amino acids in a ΔyhfW mutant. RNA-seq analysis of ΔyhfW revealed higher expression of the NAD synthesis genes nadA, nadB and nadC.
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Affiliation(s)
- Mirjam Boonstra
- Molecular Genetics group, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, the Netherlands
| | - Marc Schaffer
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Joana Sousa
- Department of Cellular Biochemistry/Metabolomics, Institute of Biochemistry, University of Greifswald, Germany
| | - Luiza Morawska
- Molecular Genetics group, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, the Netherlands
| | - Siger Holsappel
- Molecular Genetics group, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, the Netherlands
| | - Petra Hildebrandt
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Praveen Kumar Sappa
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Hermann Rath
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Anne de Jong
- Molecular Genetics group, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, the Netherlands
| | - Michael Lalk
- Department of Cellular Biochemistry/Metabolomics, Institute of Biochemistry, University of Greifswald, Germany
| | - Ulrike Mäder
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Uwe Völker
- Department of Functional Genomics, Interfaculty Institute of Genetics and Functional Genomics, University Medicine Greifswald, Germany
| | - Oscar P Kuipers
- Molecular Genetics group, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, the Netherlands
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13
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Menn D, Sochor P, Goetz H, Tian XJ, Wang X. Intracellular Noise Level Determines Ratio Control Strategy Confined by Speed-Accuracy Trade-off. ACS Synth Biol 2019; 8:1352-1360. [PMID: 31083890 DOI: 10.1021/acssynbio.9b00030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Robust and precise ratio control of heterogeneous phenotypes within an isogenic population is an essential task, especially in the development and differentiation of a large number of cells such as bacteria, sensory receptors, and blood cells. However, the mechanisms of such ratio control are poorly understood. Here, we employ experimental and mathematical techniques to understand the combined effects of signal induction and gene expression stochasticity on phenotypic multimodality. We identify two strategies to control phenotypic ratios from an initially homogeneous population, suitable roughly to high-noise and low-noise intracellular environments, and we show that both can be used to generate precise fractional differentiation. In noisy gene expression contexts, such as those found in bacteria, induction within the circuit's bistable region is enough to cause noise-induced bimodality within a feasible time frame. However, in less noisy contexts, such as tightly controlled eukaryotic systems, spontaneous state transitions are rare and hence bimodality needs to be induced with a controlled pulse of induction that falls outside the bistable region. Finally, we show that noise levels, system response time, and ratio tuning accuracy impose trade-offs and limitations on both ratio control strategies, which guide the selection of strategy alternatives.
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Affiliation(s)
- David Menn
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85281, United States
| | - Patrick Sochor
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85281, United States
| | - Hanah Goetz
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85281, United States
| | - Xiao-Jun Tian
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85281, United States
| | - Xiao Wang
- School of Biological and Health Systems Engineering, Arizona State University, Tempe, Arizona 85281, United States
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14
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Wu G, Drufva E, Wu K. Fast genome editing in Bacillus subtilis. Eng Life Sci 2019; 19:471-477. [PMID: 32625024 DOI: 10.1002/elsc.201800164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 03/21/2019] [Accepted: 04/24/2019] [Indexed: 11/08/2022] Open
Abstract
Bacillus subtilis is a model organism for Gram-positive bacteria and widely used in the study of cellular functions and processes including protein secretion, sporulation, and signal transduction. It is also an important industrial host for the production of proteins and chemicals. Generally, genome editing of B. subtilis often needs the construction of integration vectors in Escherichia coli, linearizing the constructed plasmids, and subsequent transformation of the linear deoxyribonucleic acid via natural competence or electroporation. In this work, we examined the feasibility to directly transform and integrate B. subtilis using linear deoxyribonucleic acid from Gibson assembly without the need for cloning in E. coli. Linear deoxyribonucleic acid of 8-10 kb showed the highest transformation efficiency which was similar to that of using linearized plasmids constructed in E. coli. This method shortens the overall process from 1 week to 1 day and allows the integration of multiple genes in one step, providing a simple and fast method for genome editing in B. subtilis.
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Affiliation(s)
- Guo Wu
- Department of Chemical Engineering University of New Hampshire Durham New Hampshire USA
| | - Erin Drufva
- Department of Chemical Engineering University of New Hampshire Durham New Hampshire USA
| | - Kang Wu
- Department of Chemical Engineering University of New Hampshire Durham New Hampshire USA
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15
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Genome-Wide Characterization of the Fur Regulatory Network Reveals a Link between Catechol Degradation and Bacillibactin Metabolism in Bacillus subtilis. mBio 2018; 9:mBio.01451-18. [PMID: 30377275 PMCID: PMC6212828 DOI: 10.1128/mbio.01451-18] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many bacteria synthesize high-affinity iron chelators (siderophores). Siderophore-mediated iron acquisition is an efficient and widely utilized strategy for bacteria to meet their cellular iron requirements. One prominent class of siderophores uses catecholate groups to chelate iron. B. subtilis bacillibactin, structurally similar to enterobactin (made by enteric bacteria), is a triscatecholate siderophore that is hydrolyzed to monomeric units after import to release iron. However, the ultimate fates of these catechol compounds and their potential toxicities have not been defined previously. We performed genome-wide identification of Fur binding sites in vivo and uncovered a connection between catechol degradation and bacillibactin metabolism in B. subtilis. Besides its role in the detoxification of environmental catechols, the catechol 2,3-dioxygenase encoded by catDE also protects cells from intoxication by endogenous bacillibactin-derived catechol metabolites under iron-limited conditions. These findings shed light on the degradation pathway and precursor recycling of the catecholate siderophores. The ferric uptake regulator (Fur) is the global iron biosensor in many bacteria. Fur functions as an iron-dependent transcriptional repressor for most of its regulated genes. There are a few examples where holo-Fur activates transcription, either directly or indirectly. Recent studies suggest that apo-Fur might also act as a positive regulator and that, besides iron metabolism, the Fur regulon might encompass other biological processes such as DNA synthesis, energy metabolism, and biofilm formation. Here, we obtained a genomic view of the Fur regulatory network in Bacillus subtilis using chromatin immunoprecipitation sequencing (ChIP-seq). Besides the known Fur target sites, 70 putative DNA binding sites were identified, and the vast majority had higher occupancy under iron-sufficient conditions. Among the new sites detected, a Fur binding site in the promoter region of the catDE operon is of particular interest. This operon, encoding catechol 2,3-dioxygenase, is critical for catechol degradation and is under negative regulation of CatR and YodB. These three repressors (Fur, CatR, and YodB) function cooperatively to regulate the transcription of catDE, with Fur functioning as a sensor of iron limitation and CatR as the major sensor of catechol stress. Genetic analysis suggests that CatDE is involved in metabolism of the catecholate siderophore bacillibactin, particularly when bacillibactin is constitutively produced and accumulates intracellularly, potentially generating endogenous toxic catechol derivatives. This study documents a role for catechol degradation in bacillibactin metabolism and provides evidence that catechol 2,3-dioxygenase can detoxify endogenously produced catechol substrates in addition to its more widely studied role in biodegradation of environmental aromatic compounds and pollutants.
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16
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Kaspar J, Shields RC, Burne RA. Competence inhibition by the XrpA peptide encoded within the comX gene of Streptococcus mutans. Mol Microbiol 2018; 109:345-364. [PMID: 29802741 DOI: 10.1111/mmi.13989] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2018] [Indexed: 01/06/2023]
Abstract
Streptococcus mutans displays complex regulation of natural genetic competence. Competence development in S. mutans is controlled by a peptide derived from ComS (XIP); which along with the cytosolic regulator ComR controls the expression of the alternative sigma factor comX, the master regulator of competence development. Recently, a gene embedded within the coding region of comX was discovered and designated xrpA (comX regulatory peptide A). XrpA was found to be an antagonist of ComX, but the mechanism was not established. In this study, we reveal through both genomic and proteomic techniques that XrpA is the first described negative regulator of ComRS systems in streptococci. Transcriptomic and promoter activity assays in the ΔxrpA strain revealed an up-regulation of genes controlled by both the ComR- and ComX-regulons. An in vivo protein crosslinking and in vitro fluorescent polarization assays confirmed that the N-terminal region of XrpA were found to be sufficient in inhibiting ComR-XIP complex binding to ECom-box located within the comX promoter. This inhibitory activity was sufficient for decreases in PcomX activity, transformability and ComX accumulation. XrpA serving as a modulator of ComRS activity ultimately results in changes to subpopulation behaviors and cell fate during competence activation.
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Affiliation(s)
- Justin Kaspar
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Robert C Shields
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
| | - Robert A Burne
- Department of Oral Biology, University of Florida, Gainesville, FL, 32610, USA
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17
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Sauer C, Ver Loren van Themaat E, Boender LGM, Groothuis D, Cruz R, Hamoen LW, Harwood CR, van Rij T. Exploring the Nonconserved Sequence Space of Synthetic Expression Modules in Bacillus subtilis. ACS Synth Biol 2018; 7:1773-1784. [PMID: 29939720 DOI: 10.1021/acssynbio.8b00110] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Increasing protein expression levels is a key step in the commercial production of enzymes. Predicting promoter activity and translation initiation efficiency based solely on consensus sequences have so far met with mixed results. Here, we addressed this challenge using a "brute-force" approach by designing and synthesizing a large combinatorial library comprising ∼12 000 unique synthetic expression modules (SEMs) for Bacillus subtilis. Using GFP fluorescence as a reporter of gene expression, we obtained a dynamic expression range that spanned 5 orders of magnitude, as well as a maximal 13-fold increase in expression compared with that of the already strong veg expression module. Analyses of the synthetic modules indicated that sequences at the 5'-end of the mRNA were the most important contributing factor to the differences in expression levels, presumably by preventing formation of strong secondary mRNA structures that affect translation initiation. When the gfp coding region was replaced by the coding region of the xynA gene, encoding the industrially relevant B. subtilis xylanase enzyme, only a 3-fold improvement in xylanase production was observed. Moreover, the correlation between GFP and xylanase expression levels was weak. This suggests that the differences in expression levels between the gfp and xynA constructs were due to differences in 5'-end mRNA folding and consequential differences in the rates of translation initiation. Our data show that the use of large libraries of SEMs, in combination with high-throughput technologies, is a powerful approach to improve the production of a specific protein, but that the outcome cannot necessarily be extrapolated to other proteins.
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Affiliation(s)
- Christopher Sauer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | | | | | - Daphne Groothuis
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | - Rita Cruz
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
| | - Leendert W. Hamoen
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Colin R. Harwood
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Tjeerd van Rij
- DSM Biotechnology Center, P.O. Box 1, 2600 MA Delft, The Netherlands
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18
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Fang X, Liu Q, Bohrer C, Hensel Z, Han W, Wang J, Xiao J. Cell fate potentials and switching kinetics uncovered in a classic bistable genetic switch. Nat Commun 2018; 9:2787. [PMID: 30018349 PMCID: PMC6050291 DOI: 10.1038/s41467-018-05071-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/17/2018] [Indexed: 11/13/2022] Open
Abstract
Bistable switches are common gene regulatory motifs directing two mutually exclusive cell fates. Theoretical studies suggest that bistable switches are sufficient to encode more than two cell fates without rewiring the circuitry due to the non-equilibrium, heterogeneous cellular environment. However, such a scenario has not been experimentally observed. Here by developing a new, dual single-molecule gene-expression reporting system, we find that for the two mutually repressing transcription factors CI and Cro in the classic bistable bacteriophage λ switch, there exist two new production states, in which neither CI nor Cro is produced, or both CI and Cro are produced. We construct the corresponding potential landscape and map the transition kinetics among the four production states. These findings uncover cell fate potentials beyond the classical picture of bistable switches, and open a new window to explore the genetic and environmental origins of the cell fate decision-making process in gene regulatory networks.
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Affiliation(s)
- Xiaona Fang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Changchun, 130022, China
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
- College of Physics, Jilin University, Changchun, 130012, China
- Department of Chemistry and Physics, Stony Brook University, Stony Brook, NY, 11790, USA
| | - Qiong Liu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Changchun, 130022, China
| | - Christopher Bohrer
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
| | - Zach Hensel
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Wei Han
- College of Physics, Jilin University, Changchun, 130012, China
| | - Jin Wang
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Changchun, 130022, China.
- College of Physics, Jilin University, Changchun, 130012, China.
- Department of Chemistry and Physics, Stony Brook University, Stony Brook, NY, 11790, USA.
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, 21205, USA.
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19
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The Conserved DNA Binding Protein WhiA Influences Chromosome Segregation in Bacillus subtilis. J Bacteriol 2018; 200:JB.00633-17. [PMID: 29378890 DOI: 10.1128/jb.00633-17] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 01/22/2018] [Indexed: 11/20/2022] Open
Abstract
The DNA binding protein WhiA is conserved in Gram-positive bacteria and is present in the genetically simple cell wall-lacking mycoplasmas. The protein shows homology to eukaryotic homing endonucleases but lacks nuclease activity. WhiA was first characterized in streptomycetes, where it regulates the expression of key differentiation genes, including the cell division gene ftsZ, which is essential for sporulation. For Bacillus subtilis, it was shown that WhiA is essential when certain cell division genes are deleted. However, in B. subtilis, WhiA is not required for sporulation, and it does not seem to function as a transcription factor, despite its DNA binding activity. The exact function of B. subtilis WhiA remains elusive. We noticed that whiA mutants show an increased space between their nucleoids, and here, we describe the results of fluorescence microscopy, genetic, and transcriptional experiments to further investigate this phenomenon. It appeared that the deletion of whiA is synthetic lethal when either the DNA replication and segregation regulator ParB or the DNA replication inhibitor YabA is absent. However, WhiA does not seem to affect replication initiation. We found that a ΔwhiA mutant is highly sensitive for DNA-damaging agents. Further tests revealed that the deletion of parAB induces the SOS response, including the cell division inhibitor YneA. When yneA was inactivated, the viability of the synthetic lethal ΔwhiA ΔparAB mutant was restored. However, the nucleoid segregation phenotype remained. These findings underline the importance of WhiA for cell division and indicate that the protein also plays a role in DNA segregation.IMPORTANCE The conserved WhiA protein family can be found in most Gram-positive bacteria, including the genetically simple cell wall-lacking mycoplasmas, and these proteins play a role in cell division. WhiA has some homology with eukaryotic homing endonucleases but lacks nuclease activity. Because of its DNA binding activity, it is assumed that the protein functions as a transcription factor, but this is not the case in the model system B. subtilis The function of this protein in B. subtilis remains unclear. We noticed that a whiA mutant has a mild chromosome segregation defect. Further studies of this phenomenon provided new support for a functional role of WhiA in cell division and indicated that the protein is required for normal chromosome segregation.
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20
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Zou X, Ren Z, Wang N, Cheng Y, Jiang Y, Wang Y, Xu C. Function analysis of 5'-UTR of the cellulosomal xyl- doc cluster in Clostridium papyrosolvens. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:43. [PMID: 29467821 PMCID: PMC5815224 DOI: 10.1186/s13068-018-1040-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 02/02/2018] [Indexed: 05/04/2023]
Abstract
BACKGROUND Anaerobic, mesophilic, and cellulolytic Clostridium papyrosolvens produces an efficient cellulolytic extracellular complex named cellulosome that hydrolyzes plant cell wall polysaccharides into simple sugars. Its genome harbors two long cellulosomal clusters: cip-cel operon encoding major cellulosome components (including scaffolding) and xyl-doc gene cluster encoding hemicellulases. Compared with works on cip-cel operon, there are much fewer studies on xyl-doc mainly due to its rare location in cellulolytic clostridia. Sequence analysis of xyl-doc revealed that it harbors a 5' untranslated region (5'-UTR) which potentially plays a role in the regulation of downstream gene expression. Here, we analyzed the function of 5'-UTR of xyl-doc cluster in C. papyrosolvens in vivo via transformation technology developed in this study. RESULTS In this study, we firstly developed an electrotransformation method for C. papyrosolvens DSM 2782 before the analysis of 5'-UTR of xyl-doc cluster. In the optimized condition, a field with an intensity of 7.5-9.0 kV/cm was applied to a cuvette (0.2 cm gap) containing a mixture of plasmid and late cell suspended in exponential phase to form a 5 ms pulse in a sucrose-containing buffer. Afterwards, the putative promoter and the 5'-UTR of xyl-doc cluster were determined by sequence alignment. It is indicated that xyl-doc possesses a long conservative 5'-UTR with a complex secondary structure encompassing at least two perfect stem-loops which are potential candidates for controlling the transcriptional termination. In the last step, we employed an oxygen-independent flavin-based fluorescent protein (FbFP) as a quantitative reporter to analyze promoter activity and 5'-UTR function in vivo. It revealed that 5'-UTR significantly blocked transcription of downstream genes, but corn stover can relieve its suppression. CONCLUSIONS In the present study, our results demonstrated that 5'-UTR of the cellulosomal xyl-doc cluster blocks the transcriptional activity of promoter. However, some substrates, such as corn stover, can relieve the effect of depression of 5'-UTR. Thus, it is speculated that 5'-UTR of xyl-doc was a putative riboswitch to regulate the expression of downstream cellulosomal genes, which is helpful to understand the complex regulation of cellulosome.
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Affiliation(s)
- Xia Zou
- Research Center for Harmful Algae and Marine Biology, College of Life Science and Technology, Jinan University, Guangzhou, 510632 Guangdong Province China
| | - Zhenxing Ren
- Institute of Applied Chemistry, Shanxi University, Taiyuan, 030006 Shanxi Province China
| | - Na Wang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi Province China
| | - Yin Cheng
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi Province China
| | - Yuanyuan Jiang
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi Province China
| | - Yan Wang
- Research Center for Harmful Algae and Marine Biology, College of Life Science and Technology, Jinan University, Guangzhou, 510632 Guangdong Province China
| | - Chenggang Xu
- Key Laboratory of Chemical Biology and Molecular Engineering of Ministry of Education, Institute of Biotechnology, Shanxi University, Taiyuan, 030006 Shanxi Province China
- Single-Cell Center, CAS Key Laboratory of Biofuels and Shandong Key Laboratory of Energy Genetics, Qingdao Institute of BioEnergy and BioProcess Technology, Chinese Academy of Sciences, Qingdao, 266101 Shandong Province China
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21
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Yaseen Y, Diop A, Gancel F, Béchet M, Jacques P, Drider D. Polynucleotide phosphorylase is involved in the control of lipopeptide fengycin production in Bacillus subtilis. Arch Microbiol 2018; 200:783-791. [PMID: 29423562 DOI: 10.1007/s00203-018-1483-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 01/18/2018] [Accepted: 01/23/2018] [Indexed: 10/18/2022]
Abstract
Bacillus subtilis is a wealth source of lipopeptide molecules such as iturins, surfactins and fengycins or plipastatins endowed with a range of biological activities. These molecules, designated secondary metabolites, are synthesized via non-ribosomal peptides synthesis (NRPS) machinery and are most often subjected to a complex regulation with involvement of several regulatory factors. To gain novel insights on mechanism regulating fengycin production, we investigated the effect of the fascinating polynucleotide phosphorylase (PNPase), as well as the effect of lipopeptide surfactin. Compared to the wild type, the production of fengycin in the mutant strains B. subtilis BBG235 and BBG236 altered for PNPase has not only decreased to about 70 and 40%, respectively, but also hampered its antifungal activity towards the plant pathogen Botrytis cinerea. On the other hand, mutant strains BBG231 (srfAA-) and BBG232 (srfAC-) displayed different levels of fengycin production. BBG231 had registered an important decrease in fengycin production, comparable to that observed for BBG235 or BBG236. This study permitted to establish that the products of pnpA gene (PNPase), and srfAA- (surfactin synthetase) are involved in fengycin production.
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Affiliation(s)
- Yazen Yaseen
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France
| | - Awa Diop
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France
| | - Frédérique Gancel
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France
| | - Max Béchet
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France
| | - Philippe Jacques
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France
| | - Djamel Drider
- Université de Lille, INRA, Université d'Artois, Université du Littoral-Côte d'Opale, EA 7394 - ICV-Institut Charles Viollette, F-59000, Lille, France.
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22
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Diethmaier C, Chawla R, Canzoneri A, Kearns DB, Lele PP, Dubnau D. Viscous drag on the flagellum activates Bacillus subtilis entry into the K-state. Mol Microbiol 2017; 106:367-380. [PMID: 28800172 DOI: 10.1111/mmi.13770] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/08/2017] [Indexed: 12/23/2022]
Abstract
Bacillus subtilis flagella are not only required for locomotion but also act as sensors that monitor environmental changes. Although how the signal transmission takes place is poorly understood, it has been shown that flagella play an important role in surface sensing by transmitting a mechanical signal to control the DegS-DegU two-component system. Here we report a role for flagella in the regulation of the K-state, which enables transformability and antibiotic tolerance (persistence). Mutations impairing flagellar synthesis are inferred to increase DegU-P, which inhibits the expression of ComK, the master regulator for the K-state, and reduces transformability. Tellingly, both deletion of the flagellin gene and straight filament (hagA233V ) mutations increased DegU phosphorylation despite the fact that both mutants had wild type numbers of basal bodies and the flagellar motors were functional. We propose that higher viscous loads on flagellar motors result in lower DegU-P levels through an unknown signaling mechanism. This flagellar-load based mechanism ensures that cells in the motile subpopulation have a tenfold enhanced likelihood of entering the K-state and taking up DNA from the environment. Further, our results suggest that the developmental states of motility and competence are related and most commonly occur in the same epigenetic cell type.
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Affiliation(s)
- Christine Diethmaier
- Public Health Research Institute Center, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Ravi Chawla
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station Texas, TX, USA
| | | | - Daniel B Kearns
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station Texas, TX, USA
| | - David Dubnau
- Public Health Research Institute Center, New Jersey Medical School, Rutgers University, Newark, NJ, USA
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23
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The heterocyst regulatory protein HetP and its homologs modulate heterocyst commitment in Anabaena sp. strain PCC 7120. Proc Natl Acad Sci U S A 2016; 113:E6984-E6992. [PMID: 27791130 DOI: 10.1073/pnas.1610533113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The commitment of differentiating cells to a specialized fate is fundamental to the correct assembly of tissues within a multicellular organism. Because commitment is often irreversible, entry into and progression through this phase of development must be tightly regulated. Under nitrogen-limiting conditions, the multicellular cyanobacterium Anabaena sp. strain PCC 7120 terminally commits ∼10% of its cells to become specialized nitrogen-fixing heterocysts. Although commitment is known to occur 9-14 h after the induction of differentiation, the factors that regulate the initiation and duration of this phase have yet to be elucidated. Here, we report the identification of four genes that share a functional domain and modulate heterocyst commitment: hetP (alr2818), asl1930, alr2902, and alr3234 Epistatic relationships between all four genes relating to commitment were revealed by deleting them individually and in combination; asl1930 and alr3234 acted most upstream to delay commitment, alr2902 acted next in the pathway to inhibit development, and hetP acted most downstream to drive commitment forward. Possible protein-protein interactions between HetP, its homologs, and the heterocyst master regulator, HetR, were assessed, and interaction partners were defined. Finally, patterns of gene expression for each homolog, as determined by promoter fusions to gfp and reverse transcription-quantitative PCR, were distinct from that of hetP in both spatiotemporal organization and regulation. We posit that a dynamic succession of protein-protein interactions modulates the timing and efficiency of the commitment phase of development and note that this work highlights the utility of a multicellular cyanobacterium as a model for the study of developmental processes.
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Cascante-Estepa N, Gunka K, Stülke J. Localization of Components of the RNA-Degrading Machine in Bacillus subtilis. Front Microbiol 2016; 7:1492. [PMID: 27708634 PMCID: PMC5030255 DOI: 10.3389/fmicb.2016.01492] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 09/07/2016] [Indexed: 11/17/2022] Open
Abstract
In bacteria, the control of mRNA stability is crucial to allow rapid adaptation to changing conditions. In most bacteria, RNA degradation is catalyzed by the RNA degradosome, a protein complex composed of endo- and exoribonucleases, RNA helicases, and accessory proteins. In the Gram-positive model organism Bacillus subtilis, the existence of a RNA degradosome assembled around the membrane-bound endoribonuclease RNase Y has been proposed. Here, we have studied the intracellular localization of the protein that have been implicated in the potential B. subtilis RNA degradosome, i.e., polynucleotide phosphorylase, the exoribonucleases J1 and J2, the DEAD-box RNA helicase CshA, and the glycolytic enzymes enolase and phosphofructokinase. Our data suggests that the bulk of these enzymes is located in the cytoplasm. The RNases J1 and J2 as well as the RNA helicase CshA were mainly localized in the peripheral regions of the cell where also the bulk of messenger RNA is localized. We were able to demonstrate active exclusion of these proteins from the transcribing nucleoid. Taken together, our findings suggest that the interactions of the enzymes involved in RNA degradation in B. subtilis are rather transient.
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Affiliation(s)
- Nora Cascante-Estepa
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen Göttingen, Germany
| | - Katrin Gunka
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen Göttingen, Germany
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Disselkoen C, Greco B, Cook K, Koch K, Lerebours R, Viss C, Cape J, Held E, Ashenafi Y, Fischer K, Acosta A, Cunningham M, Best AA, DeJongh M, Tintle N. A Bayesian Framework for the Classification of Microbial Gene Activity States. Front Microbiol 2016; 7:1191. [PMID: 27555837 PMCID: PMC4977825 DOI: 10.3389/fmicb.2016.01191] [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: 12/19/2015] [Accepted: 07/19/2016] [Indexed: 11/29/2022] Open
Abstract
Numerous methods for classifying gene activity states based on gene expression data have been proposed for use in downstream applications, such as incorporating transcriptomics data into metabolic models in order to improve resulting flux predictions. These methods often attempt to classify gene activity for each gene in each experimental condition as belonging to one of two states: active (the gene product is part of an active cellular mechanism) or inactive (the cellular mechanism is not active). These existing methods of classifying gene activity states suffer from multiple limitations, including enforcing unrealistic constraints on the overall proportions of active and inactive genes, failing to leverage a priori knowledge of gene co-regulation, failing to account for differences between genes, and failing to provide statistically meaningful confidence estimates. We propose a flexible Bayesian approach to classifying gene activity states based on a Gaussian mixture model. The model integrates genome-wide transcriptomics data from multiple conditions and information about gene co-regulation to provide activity state confidence estimates for each gene in each condition. We compare the performance of our novel method to existing methods on both simulated data and real data from 907 E. coli gene expression arrays, as well as a comparison with experimentally measured flux values in 29 conditions, demonstrating that our method provides more consistent and accurate results than existing methods across a variety of metrics.
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Affiliation(s)
- Craig Disselkoen
- Department of Mathematics, Statistics and Computer Science, Dordt College Sioux Center, IA, USA
| | - Brian Greco
- Department of Biostatistics, School of Public Health, University of MichiganAnn Arbor, MI, USA; Department of Statistics, University of TexasAustin, TX, USA
| | - Kaitlyn Cook
- Department of Biostatistics, Harvard University Boston, MA, USA
| | - Kristin Koch
- Department of Statistics, Baylor University Waco, TX, USA
| | | | - Chase Viss
- Department of Mathematics, University of Denver Denver, CO, USA
| | - Joshua Cape
- Department of Applied Mathematics and Statistics, Johns Hopkins University Baltimore, MD, USA
| | - Elizabeth Held
- Department of Biostatistics, University of Iowa Iowa City, IA, USA
| | - Yonatan Ashenafi
- Department of Mathematics, Statistics and Computer Science, Dordt College Sioux Center, IA, USA
| | - Karen Fischer
- Department of Statistics, Texas A&M University College Station, TX, USA
| | - Allyson Acosta
- Department of Computer Science, Hope College Holland, MI, USA
| | | | - Aaron A Best
- Department of Biology, Hope College Holland, MI, USA
| | - Matthew DeJongh
- Department of Computer Science, Hope College Holland, MI, USA
| | - Nathan Tintle
- Department of Mathematics, Statistics and Computer Science, Dordt College Sioux Center, IA, USA
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Schultz D. Coordination of cell decisions and promotion of phenotypic diversity in B. subtilis via pulsed behavior of the phosphorelay. Bioessays 2016; 38:440-5. [PMID: 26941227 DOI: 10.1002/bies.201500199] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The phosphorelay of Bacillus subtilis, a kinase cascade that activates master regulator Spo0A ~ P in response to starvation signals, is the core of a large network controlling the cell's decision to differentiate into sporulation and other phenotypes. This article reviews recent advances in understanding the origins and purposes of the complex dynamical behavior of the phosphorelay, which pulses with peaks of activity coordinated with the cell cycle. The transient imbalance in the expression of two critical genes caused by their strategic placement at opposing ends of the chromosome proved to be the key for this pulsed behavior. Feedback control loops in the phosphorelay use these pulses to implement a timer mechanism, which creates several windows of opportunity for phenotypic transitions over multiple generations. This strategy allows the cell to coordinate multiple differentiation programs in a decision process that fosters phenotypic diversity and adapts to current conditions.
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Affiliation(s)
- Daniel Schultz
- Department of Systems Biology, Harvard Medical School, Boston, MA, USA
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27
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Rahmer R, Morabbi Heravi K, Altenbuchner J. Construction of a Super-Competent Bacillus subtilis 168 Using the P mtlA -comKS Inducible Cassette. Front Microbiol 2015; 6:1431. [PMID: 26732353 PMCID: PMC4685060 DOI: 10.3389/fmicb.2015.01431] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/01/2015] [Indexed: 11/16/2022] Open
Abstract
Competence is a physiological state that enables Bacillus subtilis 168 to take up and internalize extracellular DNA. In practice, only a small subpopulation of B. subtilis 168 cells becomes competent when they enter stationary phase. In this study, we developed a new transformation method to improve the transformation efficiency of B. subtilis 168, specially in rich media. At first, different competence genes, namely comK, comS, and dprA, were alone or together integrated into the chromosome of B. subtilis 168 under control of mannitol-inducible PmtlA promoter. Overexpression of both comK and comS increased the transformation efficiency of B. subtilis REG19 with plasmid DNA by 6.7-fold compared to the wild type strain 168. This transformation efficiency reached its maximal level after 1.5 h of induction by mannitol. Besides, transformability of the REG19 cells was saturated in the presence of 100 ng dimeric plasmid or 3000 ng chromosomal DNA. Studying the influence of global regulators on the development of competence pointed out that important competence development factors, such as Spo0A, ComQXPA, and DegU, could be removed in REG19. On the other hand, efficient REG19 transformation remained highly dependent on the original copies of comK and comS regardless of the presence of PmtlA-comKS. Finally, novel plasmid-free strategies were used for transformation of REG19 based on Gibson assembly.
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Affiliation(s)
- Regine Rahmer
- Institut für Industrielle Genetik, Universität Stuttgart Stuttgart, Germany
| | | | - Josef Altenbuchner
- Institut für Industrielle Genetik, Universität Stuttgart Stuttgart, Germany
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Waldron D. Bimodal regulation of genetic competence. Nat Rev Genet 2015. [DOI: 10.1038/nrg3987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Affiliation(s)
- Jan Kampf
- Department of General Microbiology, Georg-August-Universität Göttingen, Göttingen, Germany
| | - Jörg Stülke
- Department of General Microbiology, Georg-August-Universität Göttingen, Göttingen, Germany
- * E-mail:
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