scholarly journals YfiB and the tripartite signaling system YfiBNR is involved in virulence of the gut invasive pathogen Shigella flexneri.

2021 ◽  
Author(s):  
Tanuka Sen ◽  
Naresh Kumar Verma
Keyword(s):  
Biofilm Formation ◽  
Shigella Flexneri ◽  
Targeted Mutagenesis ◽  
Bacterial Invasion ◽  
Bacterial Cells ◽  
Signaling System ◽  
Surface Attachment ◽  
Cellular Processes ◽  
Colonic Cells

Shigella flexneri is one of the principal cause of bacillary dysentery and contributes significantly to the worldwide implication of diarrheal infections. The presence and upsurge of multidrug resistance amongst Shigella strains, demands additional genetic analyses, advancement of new/improved drugs, and finding vaccine candidates against the pathogen. Whilst many features about the invasion of colonic cells by Shigella have been identified, fundamental gaps in information concerning in what way the bacteria transit, survive, and control gene expression, remain. Present study aims to illustrate the role of yfiB gene in Shigella virulence, which is a part of the periplasmic YfiBNR tripartite signaling system. This system is responsible for regulating cyclic-di-GMP levels inside the bacterial cells, which is a vital messenger molecule impacting varied cellular processes involving biofilm formation, cytotoxicity, motility, synthesis of exopolysaccharide, and other virulence mechanisms like adhesion and invasion of the bacteria. Through a combination of genetic, biochemical, and virulence assays, we show how knocking out the yfiB gene can disrupt the entire YfiBNR system and affect biofilm formation, bacterial invasion, surface attachment, and the virulence of Shigella. We then show how targeted mutagenesis of the significant amino acids of the YfiB protein can affect the proper functioning of the protein. This study eventually improves our understanding of the in-vivo persistence and survival of Shigella and provides a prospective new target to design anti-infective drugs and vaccines against S. flexneri and other bacterial pathogens.

scholarly journals The Bacterial Actin-Like Cytoskeleton

2006 ◽  
Vol 70 (4) ◽  
pp. 888-909 ◽  
Author(s):  
Rut Carballido-López
Keyword(s):  
Sequence Similarity ◽  
Amino Acid Sequence Similarity ◽  
Bacterial Cells ◽  
Cell Morphogenesis ◽  
Cellular Processes ◽  
Macromolecular Trafficking ◽  
Nucleoprotein Complexes ◽  
Dna Partitioning

SUMMARY Recent advances have shown conclusively that bacterial cells possess distant but true homologues of actin (MreB, ParM, and the recently uncovered MamK protein). Despite weak amino acid sequence similarity, MreB and ParM exhibit high structural homology to actin. Just like F-actin in eukaryotes, MreB and ParM assemble into highly dynamic filamentous structures in vivo and in vitro. MreB-like proteins are essential for cell viability and have been implicated in major cellular processes, including cell morphogenesis, chromosome segregation, and cell polarity. ParM (a plasmid-encoded actin homologue) is responsible for driving plasmid-DNA partitioning. The dynamic prokaryotic actin-like cytoskeleton is thought to serve as a central organizer for the targeting and accurate positioning of proteins and nucleoprotein complexes, thereby (and by analogy to the eukaryotic cytoskeleton) spatially and temporally controlling macromolecular trafficking in bacterial cells. In this paper, the general properties and known functions of the actin orthologues in bacteria are reviewed.

scholarly journals Cephalosporins target quorum sensing and suppress virulence of Pseudomonas aeruginosa in Caenorhabditis elegans infection model

2020 ◽  
Author(s):  
Lokender Kumar ◽  
Nathanael Brenner ◽  
John Brice ◽  
Judith Klein-Seetharaman ◽  
Susanta K. Sarkar
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Caenorhabditis Elegans ◽  
Quorum Sensing ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Host Cells ◽  
Infection Model ◽  
Host Immune System ◽  
Bacterial Cells

ABSTRACTPseudomonas aeruginosa utilizes a chemical social networking system referred to as quorum sensing (QS) to strategically co-ordinate the expression of virulence factors and biofilm formation. Virulence attributes damage the host cells, impair the host immune system, and protect bacterial cells from antibiotic attack. Thus, anti-QS agents may act as novel anti-infective therapeutics to treat P. aeruginosa infections. The present study was performed to evaluate the anti-QS, anti-biofilm, and anti-virulence activity of β-lactam antibiotics (carbapenems and cephalosporins) against P. aeruginosa. The anti-QS activity was quantified using Chromobacterium violaceum CV026 as a QS reporter strain. Our results showed that cephalosporins including cefepime (CP), ceftazidime (CF), and ceftriaxone (CT) exhibited potent anti-QS and anti-virulence activities against P. aeruginosa PAO1. These antibiotics significantly impaired motility phenotypes, decreased pyocyanin production, and reduced the biofilm formation by P. aeruginosa PAO1. In the present study, we studied isogenic QS mutants of PAO1: ΔLasR, ΔRhlR, ΔPqsA, and ΔPqsR and found that the levels of virulence factors of antibiotic-treated PAO1 were comparable to QS mutant strains. Molecular docking predicted high binding affinities of cephalosporins for the ligand-binding pocket of QS receptors (CviR, LasR, and PqsR). In addition, our results showed that the anti-microbial activity of aminoglycosides increased in the presence of sub-inhibitory concentrations (sub-MICs) of CP against P. aeruginosa PAO1. Further, utilizing Caenorhabditis elegans as an animal model for the in vivo anti-virulence effects of antibiotics, cephalosporins showed a significant increase in C. elegans survival by suppressing virulence factor production in P. aeruginosa. Thus, our results indicate that cephalosporins might provide a viable anti-virulence therapy in the treatment of infections caused by multi-drug resistant P. aeruginosa.

scholarly journals Comparison of Escherichia coli surface attachment methods for single-cell microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yao-Kuan Wang ◽  
Ekaterina Krasnopeeva ◽  
Ssu-Yuan Lin ◽  
Fan Bai ◽  
Teuta Pilizota ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Single Cell ◽  
Super Resolution ◽  
Bacterial Cells ◽  
Surface Attachment ◽  
Bacterial Physiology ◽  
E Coli ◽  
Single Cell Imaging ◽  
Atomic Force

AbstractFor in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate that E. coli grow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studying E. coli physiology.

Shigella flexneri Diguanylate Cyclases Regulate Virulence

2021 ◽  
Author(s):  
Ruchi Ojha ◽  
Ashley A. Dittmar ◽  
Geoffrey B. Severin ◽  
Benjamin J. Koestler
Keyword(s):  
Host Cell ◽  
Cell Invasion ◽  
Biofilm Formation ◽  
Shigella Flexneri ◽  
Acid Resistance ◽  
Host Cell Invasion ◽  
Plaque Size ◽  
Human Pathogen ◽  
Signaling System ◽  
Acid Shock

Shigella flexneri is an intracellular human pathogen that invades colonic cells and causes bloody diarrhea. S. flexneri evolved from commensal Escherichia coli , and genome comparisons reveal that S. flexneri has lost approximately 20% of its genes through the process of pathoadaptation, including a disproportionate number of genes associated with the turnover of the nucleotide-based second messenger cyclic di-guanosine monophosphate (c-di-GMP); however, the remaining c-di-GMP turnover enzymes are highly conserved. C-di-GMP regulates many behavioral changes in other bacteria in response to changing environmental conditions, including biofilm formation, but this signaling system has not been examined in S. flexneri . In this study, we expressed VCA0956, a constitutively active c-di-GMP synthesizing diguanylate cyclase (DGC) from Vibrio cholerae , in S. flexneri to determine if virulence phenotypes were regulated by c-di-GMP. We found that expressing VCA0956 in S. flexneri increased c-di-GMP levels, and this corresponds with increased biofilm formation, and reduced acid resistance, host cell invasion, and plaque size. We examined the impact of VCA0956 expression on the S. flexneri transcriptome, and found that genes related to acid resistance were repressed, and this corresponded with decreased survival to acid shock. We also found that individual S. flexneri DGC mutants exhibit reduced biofilm formation, reduced host cell invasion and plaque size, as well as increased resistance to acid shock. This study highlights the importance of c-di-GMP signaling in regulating S. flexneri virulence phenotypes Importance The intracellular human pathogen Shigella causes dysentery, resulting in as many as one million deaths per year. Currently, there is no approved vaccine for the prevention of shigellosis, and the incidence of antimicrobial resistance amongst Shigella species is on the rise. Here, we explore how the widely conserved c-di-GMP bacterial signaling system alters Shigella behaviors associated with pathogenesis. We find that expressing or removing enzymes associated with c-di-GMP synthesis results in changes in Shigella ’s ability to form biofilms, invade host cells, form lesions in host cell monolayers, and resist acid stress.

scholarly journals Shigella flexneri Adherence Factor Expression in In Vivo-Like Conditions

mSphere ◽  
2019 ◽  
Vol 4 (6) ◽  
Author(s):  
Rachael B. Chanin ◽  
Kourtney P. Nickerson ◽  
Alejandro Llanos-Chea ◽  
Jeticia R. Sistrunk ◽  
David A. Rasko ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Biofilm Formation ◽  
Bile Salts ◽  
Vaccine Development ◽  
Shigella Flexneri ◽  
Colonic Epithelium ◽  
Structural Genes ◽  
Content Type ◽  
Factor Expression

ABSTRACT The Shigella species are Gram-negative, facultative intracellular pathogens that invade the colonic epithelium and cause significant diarrheal disease. Despite extensive research on the pathogen, a comprehensive understanding of how Shigella initiates contact with epithelial cells remains unknown. Shigella maintains many of the same Escherichia coli adherence gene operons; however, at least one critical gene component in each operon is currently annotated as a pseudogene in reference genomes. These annotations, coupled with a lack of structures upon microscopic analysis following growth in laboratory media, have led the field to hypothesize that Shigella is unable to produce fimbriae or other traditional adherence factors. Nevertheless, our previous analyses have demonstrated that a combination of bile salts and glucose induces both biofilm formation and adherence to colonic epithelial cells. The goal of this study was to perform transcriptomic and genetic analyses to demonstrate that adherence gene operons in Shigella flexneri strain 2457T are functional, despite the gene annotations. Our results demonstrate that at least three structural genes facilitate S. flexneri 2457T adherence for epithelial cell contact and biofilm formation. Furthermore, our results demonstrate that host factors, namely, glucose and bile salts at their physiological concentrations in the small intestine, offer key environmental stimuli required for adherence factor expression in S. flexneri. This research may have a significant impact on Shigella vaccine development and further highlights the importance of utilizing in vivo-like conditions to study bacterial pathogenesis. IMPORTANCE Bacterial pathogens have evolved to regulate virulence gene expression at critical points in the colonization and infection processes to successfully cause disease. The Shigella species infect the epithelial cells lining the colon to result in millions of cases of diarrhea and a significant global health burden. As antibiotic resistance rates increase, understanding the mechanisms of infection is vital to ensure successful vaccine development. Despite significant gains in our understanding of Shigella infection, it remains unknown how the bacteria initiate contact with the colonic epithelium. Most pathogens harbor multiple adherence factors to facilitate this process, but Shigella was thought to have lost the ability to produce these factors. Interestingly, we have identified conditions that mimic some features of gastrointestinal transit and that enable Shigella to express adherence structural genes. This work highlights aspects of genetic regulation for Shigella adherence factors and may have a significant impact on future vaccine development.

scholarly journals Flagellar stators stimulate c-di-GMP production by Pseudomonas aeruginosa

2018 ◽  
Author(s):  
Amy E. Baker ◽  
Shanice S. Webster ◽  
Andreas Diepold ◽  
Sherry L. Kuchma ◽  
Eric Bordeleau ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Feedback Loop ◽  
Bacterial Cells ◽  
Diguanylate Cyclase ◽  
Flagellar Motility ◽  
Swarming Motility ◽  
Surface Attachment ◽  
Bidirectional Interactions ◽  
Gmp Production

AbstractFlagellar motility is critical for surface attachment and biofilm formation in many bacteria. A key regulator of flagellar motility in Pseudomonas aeruginosa and other microbes is cyclic diguanylate (c-di-GMP). High levels of this second messenger repress motility and stimulate biofilm formation. C-di-GMP levels regulate motility in P. aeruginosa in part by influencing the localization of its two flagellar stator sets, MotAB and MotCD. Here we show that just as c-di-GMP can influence the stators, stators can impact c-di-GMP levels. We demonstrate that the swarming motility-driving stator MotC physically interacts with the transmembrane region of the diguanylate cyclase SadC. Furthermore, we demonstrate that this interaction is capable of stimulating SadC activity. We propose a model by which the MotCD stator set interacts with SadC to stimulate c-di-GMP production in conditions not permissive to motility. This regulation implies a positive feedback loop in which c-di-GMP signaling events cause MotCD stators to disengage from the motor; then disengaged stators stimulate c-di-GMP production to reinforce a biofilm mode of growth. Our studies help define the bidirectional interactions between c-di-GMP and the motility machinery.Importance.The ability of bacterial cells to control motility during early steps in biofilm formation is critical for the transition to a non-motile, biofilm lifestyle. Recent studies have clearly demonstrated the ability of c-di-GMP to control motility via a number of mechanisms, including through controlling transcription of motility-related genes and modulating motor function. Here we provide evidence that motor components can in turn impact c-di-GMP levels. We propose that communication between motor components and c-di-GMP synthesis machinery allows the cell to have a robust and sensitive switching mechanism to control motility during early events in biofilm formation.

scholarly journals Evidence for Escherichia coli Diguanylate Cyclase DgcZ Interlinking Surface Sensing and Adhesion via Multiple Regulatory Routes

2016 ◽  
Vol 198 (18) ◽  
pp. 2524-2535 ◽  
Author(s):  
Egidio Lacanna ◽  
Colette Bigosch ◽  
Volkhard Kaever ◽  
Alex Boehm ◽  
Anke Becker
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Bacterial Infections ◽  
Primary Role ◽  
Bacterial Cells ◽  
Diguanylate Cyclase ◽  
Surface Attachment ◽  
Content Type ◽  
Surface Sensing

ABSTRACTDgcZ is the main cyclic dimeric GMP (c-di-GMP)-producing diguanylate cyclase (DGC) controlling biosynthesis of the exopolysaccharide poly-β-1,6-N-acetylglucosamine (poly-GlcNAc or PGA), which is essential for surface attachment ofEscherichia coli. Although the complex regulation of DgcZ has previously been investigated, its primary role and the physiological conditions under which the protein is active are not fully understood. Transcription ofdgcZis regulated by the two-component system CpxAR activated by the lipoprotein NlpE in response to surface sensing. Here, we show that the negative effect of acpxRmutation and the positive effect ofnlpEoverexpression on biofilm formation both depend on DgcZ. Coimmunoprecipitation data suggest several potential interaction partners of DgcZ. Interaction with FrdB, a subunit of the fumarate reductase complex (FRD) involved in anaerobic respiration and in control of flagellum assembly, was further supported by a bacterial-two-hybrid assay. Furthermore, the FRD complex was required for the increase in DgcZ-mediated biofilm formation upon induction of oxidative stress by addition of paraquat. A DgcZ-mVENUS fusion protein was found to localize at one bacterial cell pole in response to alkaline pH and carbon starvation. Based on our data and previous knowledge, an integrative role of DgcZ in regulation of surface attachment is proposed. We speculate that both DgcZ-stimulated PGA biosynthesis and interaction of DgcZ with the FRD complex contribute to impeding bacterial escape from the surface.IMPORTANCEBacterial cells can grow by clonal expansion to surface-associated biofilms that are ubiquitous in the environment but also constitute a pervasive problem related to bacterial infections. Cyclic dimeric GMP (c-di-GMP) is a widespread bacterial second messenger involved in regulation of motility and biofilm formation, and plays a primary role in bacterial surface attachment.E. colipossesses a plethora of c-di-GMP-producing diguanylate cyclases, including DgcZ. Our study expands the knowledge on the role of DgcZ in regulation of surface attachment and suggests that it interconnects surface sensing and adhesion via multiple routes.

scholarly journals Flagellar Stators Stimulate c-di-GMP Production by Pseudomonas aeruginosa

2019 ◽  
Vol 201 (18) ◽  
Author(s):  
Amy E. Baker ◽  
Shanice S. Webster ◽  
Andreas Diepold ◽  
Sherry L. Kuchma ◽  
Eric Bordeleau ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Feedback Loop ◽  
Bacterial Cells ◽  
Flagellar Motility ◽  
Swarming Motility ◽  
Surface Attachment ◽  
Content Type ◽  
Bidirectional Interactions ◽  
Gmp Production

ABSTRACT Flagellar motility is critical for surface attachment and biofilm formation in many bacteria. A key regulator of flagellar motility in Pseudomonas aeruginosa and other microbes is cyclic diguanylate (c-di-GMP). High levels of this second messenger repress motility and stimulate biofilm formation. c-di-GMP levels regulate motility in P. aeruginosa in part by influencing the localization of its two flagellar stator sets, MotAB and MotCD. Here, we show that while c-di-GMP can influence stator localization, stators can in turn impact c-di-GMP levels. We demonstrate that the swarming motility-driving stator MotC physically interacts with the transmembrane region of the diguanylate cyclase SadC. Furthermore, we demonstrate that this interaction is capable of stimulating SadC activity. We propose a model by which the MotCD stator set interacts with SadC to stimulate c-di-GMP production under conditions not permissive to motility. This regulation implies a positive-feedback loop in which c-di-GMP signaling events cause MotCD stators to disengage from the motor; then disengaged stators stimulate c-di-GMP production to reinforce a biofilm mode of growth. Our studies help to define the bidirectional interactions between c-di-GMP and the flagellar machinery. IMPORTANCE The ability of bacterial cells to control motility during early steps in biofilm formation is critical for the transition to a nonmotile, biofilm lifestyle. Recent studies have clearly demonstrated the ability of c-di-GMP to control motility via a number of mechanisms, including through controlling transcription of motility-related genes and modulating motor function. Here, we provide evidence that motor components can in turn impact c-di-GMP levels. We propose that communication between motor components and the c-di-GMP synthesis machinery allows the cell to have a robust and sensitive switching mechanism to control motility during early events in biofilm formation.

scholarly journals Comparison ofEscherichia colisurface attachment methods for single-cell,in vivomicroscopy

2019 ◽  
Author(s):  
Yao-Kuan Wang ◽  
Ekaterina Krasnopeeva ◽  
Ssu-Yuan Lin ◽  
Fan Bai ◽  
Teuta Pilizota ◽  
...  
Keyword(s):  
Single Cell ◽  
Super Resolution ◽  
Bacterial Cells ◽  
Surface Attachment ◽  
Bacterial Physiology ◽  
E Coli ◽  
Single Cell Imaging ◽  
Atomic Force ◽  
Internal Ph

ABSTRACTForin vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacteriumEscherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate thatE. coligrow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studyingE. coliphysiology.

scholarly journals Evaluation of Biofilm Formation and Anti-biofilm Properties of Peganum Harmala and Crocus Sativus in Shigella Flexneri Clinical Isolates

2019 ◽  
Vol 13 (1) ◽  
pp. 297-300
Author(s):  
Mahsa Jalili ◽  
Mansour Amraei ◽  
Nourkhoda Sadeghifard ◽  
Sobhan Ghafourian
Keyword(s):  
Biofilm Formation ◽  
Bacterial Infections ◽  
Shigella Flexneri ◽  
Herbal Medicines ◽  
Clinical Isolates ◽  
Crocus Sativus ◽  
Peganum Harmala ◽  
Chronic Infections ◽  
Traditional Use

Background: Biofilm formation causes many serious problems in the treatment of bacterial infections. In addition, chronic infections due to biofilm formation can pose a huge burden to the health care systems. Also, many bacteria are biofilm producers as an important strategy for pathogenicity. Furthermore, the traditional use of herbal medicines such as Peganum harmala and Crocus sativus in Iran is interesting. Objective: The purpose of the current study was to investigate the biofilm formation in Shigella flexneri clinical isolates and to evaluate the anti-biofilm properties of P. harmala and C. sativus on Shigella flexneri clinical isolates. Methods: For the study purpose, Thirty S.flexneri clinical isolates were collected from Ahvaz, Iran. Then, the collected bacteria were subjected to biofilm formation assay. Afterward, P. harmala and C. sativus were applied as an anti-biofilm formation in S. flexneri. Results & Conclusion: Our results demonstrated that a significant number of samples were identified as strong biofilm producers. Then, P. harmala and C . sativus in a concentration of 30μg/ml and 60μg/ml were able to eradicate a strong biofilm formation in S. flexneri, respectively. In addition, it seems that more extensive studies and in vivo research should be done to confirm their properties.

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