scholarly journals Chromosome Segregation Proteins of Vibrio cholerae as Transcription Regulators

mBio ◽  
2014 ◽  
Vol 5 (3) ◽  
Author(s):  
Jong Hwan Baek ◽  
Seesandra V. Rajagopala ◽  
Dhruba K. Chattoraj
Keyword(s):  
Vibrio Cholerae ◽  
Chromosome Segregation ◽  
Transcription Analysis ◽  
Par Proteins ◽  
Content Type ◽  
Cell Functions ◽  
Genome Wide ◽  
Preferential Binding ◽  
Promoter Dna ◽  
Division Cell

ABSTRACT Bacterial ParA and ParB proteins are best known for their contribution to plasmid and chromosome segregation, but they may also contribute to other cell functions. In segregation, ParA interacts with ParB, which binds to parS centromere-analogous sites. In transcription, plasmid Par proteins can serve as repressors by specifically binding to their own promoters and, additionally, in the case of ParB, by spreading from a parS site to nearby promoters. Here, we have asked whether chromosomal Par proteins can likewise control transcription. Analysis of genome-wide ParB1 binding in Vibrio cholerae revealed preferential binding to the three known parS1 sites and limited spreading of ParB1 beyond the parS1 sites. Comparison of wild-type transcriptomes with those of ΔparA1, ΔparB1, and ΔparAB1 mutants revealed that two out of 20 genes (VC0067 and VC0069) covered by ParB1 spreading are repressed by both ParB1 and ParA1. A third gene (VC0076) at the outskirts of the spreading area and a few genes further away were also repressed, particularly the gene for an outer membrane protein, ompU (VC0633). Since ParA1 or ParB1 binding was not evident near VC0076 and ompU genes, the repression may require participation of additional factors. Indeed, both ParA1 and ParB1 proteins were found to interact with several V. cholerae proteins in bacterial and yeast two-hybrid screens. These studies demonstrate that chromosomal Par proteins can repress genes unlinked to parS and can do so without direct binding to the cognate promoter DNA. IMPORTANCE Directed segregation of chromosomes is essential for their maintenance in dividing cells. Many bacteria have genes (par) that were thought to be dedicated to segregation based on analogy to their roles in plasmid maintenance. It is becoming clear that chromosomal par genes are pleiotropic and that they contribute to diverse processes such as DNA replication, cell division, cell growth, and motility. One way to explain the pleiotropy is to suggest that Par proteins serve as or control other transcription factors. We tested this model by determining how Par proteins affect genome-wide transcription activity. We found that genes implicated in drug resistance, stress response, and pathogenesis were repressed by Par. Unexpectedly, the repression did not involve direct Par binding to cognate promoter DNA, indicating that the repression may involve Par interactions with other regulators. This pleiotropy highlights the degree of integration of chromosomal Par proteins into cellular control circuitries.

scholarly journals Phylodynamic Analysis of Clinical and Environmental Vibrio cholerae Isolates from Haiti Reveals Diversification Driven by Positive Selection

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Taj Azarian ◽  
Afsar Ali ◽  
Judith A. Johnson ◽  
David Mohr ◽  
Mattia Prosperi ◽  
...  
Keyword(s):  
Positive Selection ◽  
Vibrio Cholerae ◽  
Short Time Scale ◽  
Single Nucleotide ◽  
Content Type ◽  
Nonsynonymous Substitutions ◽  
Genome Wide ◽  
Close Phylogenetic Relationship ◽  
Phylodynamic Analysis ◽  
Over Time

ABSTRACTPhylodynamic analysis of genome-wide single-nucleotide polymorphism (SNP) data is a powerful tool to investigate underlying evolutionary processes of bacterial epidemics. The method was applied to investigate a collection of 65 clinical and environmental isolates ofVibrio choleraefrom Haiti collected between 2010 and 2012. Characterization of isolates recovered from environmental samples identified a total of four toxigenicV. choleraeO1 isolates, four non-O1/O139 isolates, and a novel nontoxigenicV. choleraeO1 isolate with the classicaltcpAgene. Phylogenies of strains were inferred from genome-wide SNPs using coalescent-based demographic models within a Bayesian framework. A close phylogenetic relationship between clinical and environmental toxigenicV. choleraeO1 strains was observed. As cholera spread throughout Haiti between October 2010 and August 2012, the population size initially increased and then fluctuated over time. Selection analysis along internal branches of the phylogeny showed a steady accumulation of synonymous substitutions and a progressive increase of nonsynonymous substitutions over time, suggesting diversification likely was driven by positive selection. Short-term accumulation of nonsynonymous substitutions driven by selection may have significant implications for virulence, transmission dynamics, and even vaccine efficacy.IMPORTANCECholera, a dehydrating diarrheal disease caused by toxigenic strains of the bacteriumVibrio cholerae, emerged in 2010 in Haiti, a country where there were no available records on cholera over the past 100 years. While devastating in terms of morbidity and mortality, the outbreak provided a unique opportunity to study the evolutionary dynamics ofV. choleraeand its environmental presence. The present study expands on previous work and provides an in-depth phylodynamic analysis inferred from genome-wide single nucleotide polymorphisms of clinical and environmental strains from dispersed geographic settings in Haiti over a 2-year period. Our results indicate that even during such a short time scale,V. choleraein Haiti has undergone evolution and diversification driven by positive selection, which may have implications for understanding the global clinical and epidemiological patterns of the disease. Furthermore, the continued presence of the epidemic strain in Haitian aquatic environments has implications for transmission.

scholarly journals The ParB-parS Chromosome Segregation System Modulates Competence Development in Streptococcus pneumoniae

mBio ◽  
2015 ◽  
Vol 6 (4) ◽  
Author(s):  
Laetitia Attaiech ◽  
Anita Minnen ◽  
Morten Kjos ◽  
Stephan Gruber ◽  
Jan-Willem Veening
Keyword(s):  
Streptococcus Pneumoniae ◽  
Chromosome Segregation ◽  
Dna Sequences ◽  
Molecular Mechanisms ◽  
Developmental Process ◽  
Competence Development ◽  
Human Pathogen ◽  
Transcription Analysis ◽  
Exogenous Dna ◽  
Content Type

ABSTRACT ParB proteins bind centromere-like DNA sequences called parS sites and are involved in plasmid and chromosome segregation in bacteria. We previously showed that the opportunistic human pathogen Streptococcus pneumoniae contains four parS sequences located close to the origin of replication which are bound by ParB. Using chromatin immunoprecipitation (ChIP), we found here that ParB spreads out from one of these parS sites, parS(−1.6°), for more than 5 kb and occupies the nearby comCDE operon, which drives competence development. Competence allows S. pneumoniae to take up DNA from its environment, thereby mediating horizontal gene transfer, and is also employed as a general stress response. Mutating parS(−1.6°) or deleting parB resulted in transcriptional up-regulation of comCDE and ssbB (a gene belonging to the competence regulon), demonstrating that ParB acts as a repressor of competence. However, genome-wide transcription analysis showed that ParB is not a global transcriptional regulator. Different factors, such as the composition of the growth medium and antibiotic-induced stress, can trigger the sensitive switch driving competence. This work shows that the ParB-parS chromosome segregation machinery also influences this developmental process. IMPORTANCE Streptococcus pneumoniae (pneumococcus) is an important human pathogen responsible for more than a million deaths each year. Like all other organisms, S. pneumoniae must be able to segregate its chromosomes properly. Not only is understanding the molecular mechanisms underlying chromosome segregation in S. pneumoniae therefore of fundamental importance, but also, this knowledge might offer new leads for ways to target this pathogen. Here, we identified a link between the pneumococcal chromosome segregation system and the competence-developmental system. Competence allows S. pneumoniae to take up and integrate exogenous DNA in its chromosome. This process plays a crucial role in successful adaptation to—and escape from—host defenses, antibiotic treatments, and vaccination strategies. We show that the chromosome segregation protein ParB acts as a repressor of competence. To the best of our knowledge, this is the first example of a ParB protein controlling bacterial competence.

scholarly journals ¡vIVA la DivIVA!

2019 ◽  
Vol 201 (21) ◽  
Author(s):  
Lauren R. Hammond ◽  
Maria L. White ◽  
Prahathees J. Eswara
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Parental Cell ◽  
Model Organisms ◽  
Posttranslational Regulation ◽  
Bacterial Cell Division ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Division Cell

ABSTRACT Reproduction in the bacterial kingdom predominantly occurs through binary fission—a process in which one parental cell is divided into two similarly sized daughter cells. How cell division, in conjunction with cell elongation and chromosome segregation, is orchestrated by a multitude of proteins has been an active area of research spanning the past few decades. Together, the monumental endeavors of multiple laboratories have identified several cell division and cell shape regulators as well as their underlying regulatory mechanisms in rod-shaped Escherichia coli and Bacillus subtilis, which serve as model organisms for Gram-negative and Gram-positive bacteria, respectively. Yet our understanding of bacterial cell division and morphology regulation is far from complete, especially in noncanonical and non-rod-shaped organisms. In this review, we focus on two proteins that are highly conserved in Gram-positive organisms, DivIVA and its homolog GpsB, and attempt to summarize the recent advances in this area of research and discuss their various roles in cell division, cell growth, and chromosome segregation in addition to their interactome and posttranslational regulation.

scholarly journals The Role of Fnr Paralogs in Controlling Anaerobic Metabolism in the Diazotroph Paenibacillus polymyxa WLY78

2020 ◽  
Vol 86 (10) ◽  
Author(s):  
Haowen Shi ◽  
Yongbin Li ◽  
Tianyi Hao ◽  
Xiaomeng Liu ◽  
Xiyun Zhao ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Paenibacillus Polymyxa ◽  
Transcription Analysis ◽  
Content Type ◽  
Double Deletion ◽  
Expression Of Genes ◽  
Genome Wide ◽  
Promoter Deletion Analysis ◽  
Single Deletion

ABSTRACT Fnr is a transcriptional regulator that controls the expression of a variety of genes in response to oxygen limitation in bacteria. Genome sequencing revealed four genes (fnr1, fnr3, fnr5, and fnr7) coding for Fnr proteins in Paenibacillus polymyxa WLY78. Fnr1 and Fnr3 showed more similarity to each other than to Fnr5 and Fnr7. Also, Fnr1 and Fnr3 exhibited high similarity with Bacillus cereus Fnr and Bacillus subtilis Fnr in sequence and structures. Both the aerobically purified His-tagged Fnr1 and His-tagged Fnr3 in Escherichia coli could bind to the specific DNA promoter. Deletion analysis showed that the four fnr genes, especially fnr1 and fnr3, have significant impacts on growth and nitrogenase activity. Single deletion of fnr1 or fnr3 led to a 50% reduction in nitrogenase activity, and double deletion of fnr1 and fnr3 resulted to a 90% reduction in activity. Genome-wide transcription analysis showed that Fnr1 and Fnr3 indirectly activated expression of nif (nitrogen fixation) genes and Fe transport genes under anaerobic conditions. Fnr1 and Fnr3 inhibited expression of the genes involved in the aerobic respiratory chain and activated expression of genes responsible for anaerobic electron acceptor genes. IMPORTANCE The members of the nitrogen-fixing Paenibacillus spp. have great potential to be used as a bacterial fertilizer in agriculture. However, the functions of the fnr gene(s) in nitrogen fixation and other metabolisms in Paenibacillus spp. are not known. Here, we found that in P. polymyxa WLY78, Fnr1 and Fnr3 were responsible for regulation of numerous genes in response to changes in oxygen levels, but Fnr5 and Fnr7 exhibited little effect. Fnr1 and Fnr3 indirectly or directly regulated many types of important metabolism, such as nitrogen fixation, Fe uptake, respiration, and electron transport. This study not only reveals the function of the fnr genes of P. polymyxa WLY78 in nitrogen fixation and other metabolisms but also will provide insight into the evolution and regulatory mechanisms of fnr in Paenibacillus.

scholarly journals Vibrio cholerae Virulence Activator ToxR Regulates Manganese Transport and Resistance to Reactive Oxygen Species

2019 ◽  
Vol 88 (3) ◽  
Author(s):  
Hang-hang Jiang ◽  
Yitian Zhou ◽  
Ming Liu ◽  
Jessie Larios-Valencia ◽  
Zachariah Lee ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Vibrio Cholerae ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Content Type ◽  
Genome Wide ◽  
A Genome ◽  
Its Gene ◽  
Virulence Regulator ◽  
Manganese Transport

ABSTRACT Like many other pathogens, Vibrio cholerae, the causative agent of cholera, can modulate its gene expression to combat stresses encountered in both aquatic and host environments, including stress posed by reactive oxygen species (ROS). We previously reported that the virulence activator AphB in V. cholerae is involved in ROS resistance. In this study, we found that another key virulence regulator, ToxR, was important for V. cholerae resistance to hydrogen peroxide. Through a genome-wide transposon screen, we discovered that a deletion in mneA, which encodes a manganese exporter, restored ROS resistance of the toxR mutant. We then showed that ToxR did not affect mneA transcription but that the ToxR-regulated major porin OmpU was critical for ROS resistance. The addition of manganese in culture medium restored ROS resistance in both the toxR and ompU mutants. Furthermore, elemental analysis indicated that the intracellular concentration of manganese in both the toxR and ompU mutants was reduced. This may result in intracellular ROS accumulation in these mutants. Our data suggest that ToxR plays an important role in the resistance to reactive oxygen species through the regulation of manganese transport.

scholarly journals Vibrio cholerae Represses Polysaccharide Synthesis To Promote Motility in Mucosa

2015 ◽  
Vol 83 (3) ◽  
pp. 1114-1121 ◽  
Author(s):  
Zhenyu Liu ◽  
Yuning Wang ◽  
Shengyan Liu ◽  
Ying Sheng ◽  
Karl-Gustav Rueggeberg ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Epithelial Surface ◽  
Semisolid Medium ◽  
Content Type ◽  
Infant Mouse ◽  
Genome Wide ◽  
Polysaccharide Synthesis ◽  
A Genome ◽  
Rapid Spread ◽  
Colonization Model

The viscoelastic mucus layer of gastrointestinal tracts is a host defense barrier that a successful enteric pathogen, such asVibrio cholerae, must circumvent.V. cholerae, the causative agent of cholera, is able to penetrate the mucosa and colonize the epithelial surface of the small intestine. In this study, we found that mucin, the major component of mucus, promotedV. choleraemovement on semisolid medium and in liquid medium. A genome-wide screen revealed thatVibriopolysaccharide (VPS) production was inversely correlated with mucin-enhanced motility. Mucin adhesion assays indicated that VPS bound to mucin. Moreover, we found thatvpsexpression was reduced upon exposure to mucin. In an infant mouse colonization model, mutants that overexpressed VPS colonized less effectively than wild-type strains in more distal intestinal regions. These results suggest thatV. choleraeis able to sense mucosal signals and modulatevpsexpression accordingly so as to promote fast motion in mucus, thus allowing for rapid spread throughout the intestines.

scholarly journals MetR-Regulated Vibrio cholerae Metabolism Is Required for Virulence

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
Ryan W. Bogard ◽  
Bryan W. Davies ◽  
John J. Mekalanos
Keyword(s):  
Amino Acid ◽  
Vibrio Cholerae ◽  
Virulence Factor ◽  
Current Knowledge ◽  
Intestinal Colonization ◽  
Wild Type ◽  
Pathogenic Potential ◽  
Content Type ◽  
Mouse Intestine

ABSTRACTLysR-type transcriptional regulators (LTTRs) are the largest, most diverse family of prokaryotic transcription factors, with regulatory roles spanning metabolism, cell growth and division, and pathogenesis. Using a sequence-defined transposon mutant library, we screened a panel ofV. choleraeEl Tor mutants to identify LTTRs required for host intestinal colonization. Surprisingly, out of 38 LTTRs, only one severely affected intestinal colonization in the suckling mouse model of cholera: the methionine metabolism regulator, MetR. Genetic analysis of genes influenced by MetR revealed thatglyA1andmetJwere also required for intestinal colonization. Chromatin immunoprecipitation of MetR and quantitative reverse transcription-PCR (qRT-PCR) confirmed interaction with and regulation ofglyA1, indicating that misregulation ofglyA1is likely responsible for the colonization defect observed in themetRmutant. TheglyA1mutant was auxotrophic for glycine but exhibited wild-type trimethoprim sensitivity, making folate deficiency an unlikely cause of its colonization defect. MetJ regulatory mutants are not auxotrophic but are likely altered in the regulation of amino acid-biosynthetic pathways, including those for methionine, glycine, and serine, and this misregulation likely explains its colonization defect. However, mutants defective in methionine, serine, and cysteine biosynthesis exhibited wild-type virulence, suggesting that these amino acids can be scavenged in vivo. Taken together, our results suggest that glycine biosynthesis may be required to alleviate an in vivo nutritional restriction in the mouse intestine; however, additional roles for glycine may exist. Irrespective of the precise nature of this requirement, this study illustrates the importance of pathogen metabolism, and the regulation thereof, as a virulence factor.IMPORTANCEVibrio choleraecontinues to be a severe cause of morbidity and mortality in developing countries. Identification ofV. choleraefactors critical to disease progression offers the potential to develop or improve upon therapeutics and prevention strategies. To increase the efficiency of virulence factor discovery, we employed a regulator-centric approach to multiplex our in vivo screening capabilities and allow whole regulons inV. choleraeto be interrogated for pathogenic potential. We identified MetR as a new virulence regulator and serine hydroxymethyltransferase GlyA1 as a new MetR-regulated virulence factor, both required byV. choleraeto colonize the infant mouse intestine. Bacterial metabolism is a prerequisite to virulence, and current knowledge of in vivo metabolism of pathogens is limited. Here, we expand the known role of amino acid metabolism and regulation in virulence and offer new insights into the in vivo metabolic requirements ofV. choleraewithin the mouse intestine.

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