scholarly journals Endopeptidase regulation as a novel function of the Zur-dependent zinc starvation response

2018 ◽  
Author(s):  
Shannon G. Murphy ◽  
Laura Alvarez ◽  
Myfanwy C. Adams ◽  
Shuning Liu ◽  
Joshua S. Chappie ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Zinc Homeostasis ◽  
Regulatory Control ◽  
Starvation Response ◽  
Antibiotic Development ◽  
Human Host ◽  
Growing Cell

AbstractThe cell wall is a strong, yet flexible, meshwork of peptidoglycan (PG) that gives a bacterium structural integrity. To accommodate a growing cell, the wall is remodeled by both PG synthesis and degradation.Vibrio choleraeencodes a group of three nearly identical zinc-dependent endopeptidases (EPs) that hydrolyze PG to facilitate cell growth. Two of these (shyAandshyC) are housekeeping genes and form a synthetic lethal pair, while the third (shyB) is not expressed under standard laboratory conditions. To investigate the role of ShyB, we conducted a transposon screen to identify mutations that activateshyBtranscription. We found thatshyBis induced as part of the Zur-mediated zinc starvation response, a mode of regulation not previously reported for cell wall lytic enzymes.In vivo, ShyB alone was sufficient to sustain cell growth in low-zinc environments.In vitro, ShyB retained its D,D-endopeptidase activity against purified sacculi in the presence of the metal chelator EDTA at a concentration that inhibits ShyA and ShyC. This suggests that ShyB can substitute for the other EPs during zinc starvation, a condition that pathogens encounter while infecting a human host. Our survey of transcriptomic data from diverse bacteria identified other candidate Zur-regulated endopeptidases, suggesting that this adaptation to zinc starvation is conserved in other Gram-negative bacteria.ImportanceThe human host sequesters zinc and other essential metals in order to restrict growth of potentially harmful bacteria. In response, invading bacteria express a set of genes enabling them to cope with zinc starvation. InVibrio cholerae, the causative agent of the diarrheal disease cholera, we have identified a novel member of this zinc starvation response: a cell wall hydrolase that retains function in low-zinc environments and is conditionally essential for cell growth. Other human pathogens contain homologs that appear to be under similar regulatory control. These findings are significant because they represent, to our knowledge, the first evidence that zinc homeostasis influences cell wall turnover. Anti-infective therapies commonly target the bacterial cell wall and, therefore, an improved understanding of how the cell wall adapts to host-induced zinc starvation could lead to new antibiotic development. Such therapeutic interventions are required to combat the rising threat of drug resistant infections.

scholarly journals Endopeptidase Regulation as a Novel Function of the Zur-Dependent Zinc Starvation Response

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shannon G. Murphy ◽  
Laura Alvarez ◽  
Myfanwy C. Adams ◽  
Shuning Liu ◽  
Joshua S. Chappie ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Vibrio Cholerae ◽  
Zinc Homeostasis ◽  
Regulatory Control ◽  
Gram Negative Bacteria ◽  
Starvation Response ◽  
Gram Negative ◽  
Content Type ◽  
Antibiotic Development

ABSTRACTThe cell wall is a strong, yet flexible, meshwork of peptidoglycan (PG) that gives a bacterium structural integrity. To accommodate a growing cell, the wall is remodeled by both PG synthesis and degradation.Vibrio choleraeencodes a group of three nearly identical zinc-dependent endopeptidases (EPs) that are predicted to hydrolyze PG to facilitate cell growth. Two of these (ShyA and ShyC) are conditionally essential housekeeping EPs, while the third (ShyB) is not expressed under standard laboratory conditions. To investigate the role of ShyB, we conducted a transposon screen to identify mutations that activateshyBtranscription. We found thatshyBis induced as part of the Zur-mediated zinc starvation response, a mode of regulation not previously reported for cell wall lytic enzymes.In vivo, ShyB alone was sufficient to sustain cell growth in low-zinc environments.In vitro, ShyB retained itsd,d-endopeptidase activity against purified sacculi in the presence of the metal chelator EDTA at concentrations that inhibit ShyA and ShyC. This insensitivity to metal chelation is likely what enables ShyB to substitute for other EPs during zinc starvation. Our survey of transcriptomic data from diverse bacteria identified other candidate Zur-regulated EPs, suggesting that this adaptation to zinc starvation is employed by other Gram-negative bacteria.IMPORTANCEBacteria encode a variety of adaptations that enable them to survive during zinc starvation, a condition which is encountered both in natural environments and inside the human host. InVibrio cholerae, the causative agent of the diarrheal disease cholera, we have identified a novel member of this zinc starvation response, a cell wall hydrolase that retains function and is conditionally essential for cell growth in low-zinc environments. Other Gram-negative bacteria contain homologs that appear to be under similar regulatory control. These findings are significant because they represent, to our knowledge, the first evidence that zinc homeostasis influences cell wall turnover. Anti-infective therapies commonly target the bacterial cell wall; therefore, an improved understanding of how the cell wall adapts to host-induced zinc starvation could lead to new antibiotic development. Such therapeutic interventions are required to combat the rising threat of drug-resistant infections.

scholarly journals The Structure and Plastic Properties of the Cell Wall of Nitella in Relation to Extension Growth

1966 ◽  
Vol 19 (3) ◽  
pp. 439 ◽  
Author(s):  
MC Probine ◽  
NF Barber
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
Cell Growth ◽  
Elastic Properties ◽  
Cell Shape ◽  
Cellulose Microfibrils ◽  
Theoretical Treatment ◽  
Plastic Properties ◽  
Growing Cell ◽  
Plastic Matrix

The internodal cells of Nitella opaca L. have been used in earlier studies to assess the part which mechanical properties of the wall may play in the control of cell growth (Probine and Preston 1962). The wall is mechanically anisotropic in both its plastic and elastic properties, and it is shown in this paper by an approximate theoretical treatment that a mat of cellulose microfibrils, embedded in a plastic matrix and having a distribution in the plane of the wall like that observed in Nitella, would lead to longitUdinal and transverse plastic extensions in the ratio observed in the growing cell. Factors which would affect cell shape are discussed.

scholarly journals Tol-Pal System and Rgs Proteins Interact to Promote Unipolar Growth and Cell Division in Sinorhizobium meliloti

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Elizaveta Krol ◽  
Hamish C. L. Yau ◽  
Marcus Lechner ◽  
Simon Schäper ◽  
Gert Bange ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Cell Growth ◽  
Cell Elongation ◽  
Sinorhizobium Meliloti ◽  
Rgs Proteins ◽  
Polar Growth ◽  
Content Type ◽  
Cell Pole ◽  
Growing Cell

ABSTRACT Sinorhizobium meliloti is an alphaproteobacterium belonging to the Rhizobiales. Bacteria from this order elongate their cell wall at the new cell pole, generated by cell division. Screening for protein interaction partners of the previously characterized polar growth factors RgsP and RgsM, we identified the inner membrane components of the Tol-Pal system (TolQ and TolR) and novel Rgs (rhizobial growth and septation) proteins with unknown functions. TolQ, Pal, and all Rgs proteins, except for RgsE, were indispensable for S. meliloti cell growth. Six of the Rgs proteins, TolQ, and Pal localized to the growing cell pole in the cell elongation phase and to the septum in predivisional cells, and three Rgs proteins localized to the growing cell pole only. The putative FtsN-like protein RgsS contains a conserved SPOR domain and is indispensable at the early stages of cell division. The components of the Tol-Pal system were required at the late stages of cell division. RgsE, a homolog of the Agrobacterium tumefaciens growth pole ring protein GPR, has an important role in maintaining the normal growth rate and rod cell shape. RgsD is a periplasmic protein with the ability to bind peptidoglycan. Analysis of the phylogenetic distribution of the Rgs proteins showed that they are conserved in Rhizobiales and mostly absent from other alphaproteobacterial orders, suggesting a conserved role of these proteins in polar growth. IMPORTANCE Bacterial cell proliferation involves cell growth and septum formation followed by cell division. For cell growth, bacteria have evolved different complex mechanisms. The most prevalent growth mode of rod-shaped bacteria is cell elongation by incorporating new peptidoglycans in a dispersed manner along the sidewall. A small share of rod-shaped bacteria, including the alphaproteobacterial Rhizobiales, grow unipolarly. Here, we identified and initially characterized a set of Rgs (rhizobial growth and septation) proteins, which are involved in cell division and unipolar growth of Sinorhizobium meliloti and highly conserved in Rhizobiales. Our data expand the knowledge of components of the polarly localized machinery driving cell wall growth and suggest a complex of Rgs proteins with components of the divisome, differing in composition between the polar cell elongation zone and the septum.

scholarly journals Genes Activated byVibrio choleraeupon Exposure toCaenorhabditis elegansReveal the Mannose-Sensitive Hemagglutinin To Be Essential for Colonization

mSphere ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Cornelia List ◽  
Andreas Grutsch ◽  
Claudia Radler ◽  
Fatih Cakar ◽  
Franz G. Zingl ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Vibrio Cholerae ◽  
Developmental Delay ◽  
Growth Retardation ◽  
Aquatic Environment ◽  
Diarrheal Disease ◽  
Phenotypic Characterization ◽  
Human Pathogen ◽  
Content Type ◽  
Human Host

ABSTRACTDuring its life cycle, the facultative human pathogenVibrio cholerae, which is the causative agent of the diarrheal disease cholera, needs to adapt to a variety of different conditions, such as the human host or the aquatic environment. Importantly, cholera infections originate from the aquatic reservoir whereV. choleraepersists between the outbreaks. In the aquatic environment, bacteria are constantly threatened by predatory protozoa and nematodes, but our knowledge of the response pathways and adaptation strategies ofV. choleraeto such stressors is limited. Using a temporally controlled reporter system of transcription, we identified more than 100 genes ofV. choleraeinduced upon exposure to the nematodeCaenorhabditis elegans, which emerged recently as a valuable model for environmental predation during the aquatic lifestyle ofV. cholerae. Besides others, we identified and validated the genes encoding the mannose-sensitive hemagglutinin (MSHA) type IV pilus to be significantly induced upon exposure to the nematode. Subsequent analyses demonstrated that the mannose-sensitive hemagglutinin is crucial for attachment ofV. choleraein the pharynx of the worm and initiation of colonization, which results in growth retardation and developmental delay ofC. elegans. Thus, the surface adhesion factor MSHA could be linked to a fitness advantage ofV. choleraeupon contact with bacterium-grazing nematodes.IMPORTANCEThe waterborne diarrheal disease cholera is caused by the bacteriumVibrio cholerae. The facultative human pathogen persists as a natural inhabitant in the aquatic ecosystem between outbreaks. In contrast to the human host,V. choleraerequires a different set of genes to survive in this hostile environment. For example, predatory micrograzers are commonly found in the aquatic environment and use bacteria as a nutrient source, but knowledge of the interaction between bacterivorous grazers andV. choleraeis limited. In this study, we successfully adapted a genetic reporter technology and identified more than 100 genes activated byV. choleraeupon exposure to the bacterium-grazing nematodeCaenorhabditis elegans. This screen provides a first glimpse into responses and adaptational strategies of the bacterial pathogen against such natural predators. Subsequent phenotypic characterization revealed the mannose-sensitive hemagglutinin to be crucial for colonization of the worm, which causes developmental delay and growth retardation.

scholarly journals Tol-Pal system and Rgs proteins interact to promote unipolar growth and cell division in Sinorhizobium meliloti

2020 ◽  
Author(s):  
Elizaveta Krol ◽  
Hamish C. L. Yau ◽  
Marcus Lechner ◽  
Simon Schäper ◽  
Gert Bange ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Cell Growth ◽  
Cell Elongation ◽  
Sinorhizobium Meliloti ◽  
Normal Growth ◽  
Rgs Proteins ◽  
Polar Growth ◽  
Cell Pole ◽  
Growing Cell

ABSTRACTSinorhizobium meliloti is an α-proteobacterium belonging to the Rhizobiales. Bacteria from this order elongate their cell wall at the new cell pole, generated by cell division. Screening for protein interaction partners of the previously characterized polar growth factors RgsP and RgsM, we identified the inner membrane components of the Tol-Pal system (TolQ and TolR) and novel Rgs (rhizobial growth and septation) proteins with unknown functions. TolQ, Pal and all Rgs proteins, except for RgsE, were indispensable for S. meliloti cell growth. Six of the Rgs proteins, TolQ and Pal localized to the growing cell pole in the cell elongation phase and to the septum in pre-divisional cells, and three Rgs proteins localized to growing cell pole only. The FtsN-like protein RgsS contains a conserved SPOR domain and is indispensable at the early stages of cell division. The components of the Tol-Pal system were required at the late stages of cell division. RgsE, a homolog of the Agrobacterium tumefaciens growth pole ring protein GPR, has an important role in maintaining the normal growth rate and rod cell shape. RgsD is a novel periplasmic protein with the ability to bind peptidoglycan. Analysis of the phylogenetic distribution of novel Rgs proteins showed that they are conserved in Rhizobiales and mostly absent from other α-proteobacterial orders, suggesting a conserved role of these proteins in polar growth.IMPORTANCEBacterial cell proliferation involves cell growth and septum formation followed by cell division. For cell growth, bacteria have evolved different complex mechanisms. The most prevalent growth mode of rod shaped bacteria is cell elongation by incorporating new peptidoglycan in a dispersed manner along the sidewall. A small share of rod-shaped bacteria, including the α-proteobacterial Rhizobiales, grow unipolarly. Here, we identified and initially characterized a set of Rgs (rhizobial growth and septation) proteins, which are involved in cell division and unipolar growth of Sinorhizobium meliloti and highly conserved in Rhizobiales. Our data expand the knowledge of components of the polarly localized machinery driving cell wall growth and suggest a complex of Rgs proteins with components of the divisome, differing in composition between the polar cell elongation zone and the septum.

Cell Wall Biology of Vibrio cholerae

2021 ◽  
Vol 75 (1) ◽  
pp. 151-174
Author(s):  
Laura Alvarez ◽  
Sara B. Hernandez ◽  
Felipe Cava
Keyword(s):  
Cell Wall ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Genetic Determinants ◽  
Cell Wall Metabolism ◽  
Gram Negative ◽  
Adaptive Mechanisms ◽  
Bacterial Morphology ◽  
A Cell ◽  
Shed Light

Most bacteria are protected from environmental offenses by a cell wall consisting of strong yet elastic peptidoglycan. The cell wall is essential for preserving bacterial morphology and viability, and thus the enzymes involved in the production and turnover of peptidoglycan have become preferred targets for many of our most successful antibiotics. In the past decades, Vibrio cholerae, the gram-negative pathogen causing the diarrheal disease cholera, has become a major model for understanding cell wall genetics, biochemistry, and physiology. More than 100 articles have shed light on novel cell wall genetic determinants, regulatory links, and adaptive mechanisms. Here we provide the first comprehensive review of V. cholerae’s cell wall biology and genetics. Special emphasis is placed on the similarities and differences with Escherichia coli, the paradigm for understanding cell wall metabolism and chemical structure in gram-negative bacteria.

scholarly journals The VarA-CsrA regulatory pathway influences cell shape in Vibrio cholerae

2021 ◽  
Author(s):  
Leonardo F. Lemos Rocha ◽  
Katharina Peters ◽  
Jamie S. Depelteau ◽  
Ariane Briegel ◽  
Waldemar Vollmer ◽  
...  
Keyword(s):  
Cell Wall ◽  
Vibrio Cholerae ◽  
Environmental Changes ◽  
Diarrheal Disease ◽  
Spherical Shape ◽  
Building Blocks ◽  
Diaminopimelic Acid ◽  
Two Component Signal Transduction ◽  
External Stimuli ◽  
Mutant Cells

AbstractDespite extensive studies on the curve-shaped bacterium Vibrio cholerae, the causative agent of the diarrheal disease cholera, its virulence-associated regulatory two-component signal transduction system VarS/VarA is not well understood. This pathway, which mainly signals through the downstream protein CsrA, is highly conserved among gamma-proteobacteria, indicating there is likely a broader function of this system beyond virulence regulation. In this study, we investigated the VarA-CsrA signaling pathway and discovered a previously unrecognized link to the shape of the bacterium. We observed that varA-deficient V. cholerae cells showed an abnormal spherical morphology during late-stage growth. Through peptidoglycan (PG) composition analyses, we discovered that these mutant bacteria contained an increased content of disaccharide dipeptides and reduced peptide crosslinks, consistent with the atypical cellular shape. The spherical shape correlated with the CsrA-dependent overproduction of aspartate ammonia lyase (AspA) in varA mutant cells, which likely depleted the cellular aspartate pool; therefore, the synthesis of the PG precursor amino acid meso-diaminopimelic acid was impaired. Importantly, this phenotype, and the overall cell rounding, could be prevented by means of cell wall recycling. Collectively, our data provide new insights into how V. cholerae use the VarA-CsrA signaling system to adjust its morphology upon unidentified external cues in its environment.Significance StatementResponsible for the diarrheal disease cholera, the bacterium Vibrio cholerae tightly regulates its virulence program according to external stimuli. Here, we discovered that a sensing-response mechanism involved in the regulation of virulence also controls bacterial shape. We show that V. cholerae lacking this system lose their normal comma shape and become spherical due to an abnormal cell wall composition caused by metabolic changes that reduce available cell wall building blocks. Our study therefore sheds new light on how V. cholerae modulates its morphology based on environmental changes.

A fibre-reinforced fluid model of anisotropic plant cell growth

2010 ◽  
Vol 655 ◽  
pp. 472-503 ◽  
Author(s):  
R. J. DYSON ◽  
O. E. JENSEN
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Fluid Model ◽  
Turgor Pressure ◽  
Cellulose Microfibrils ◽  
Wall Material ◽  
Primary Cell Wall ◽  
Growing Cell ◽  
Asymptotic Reduction ◽  
Simple Sets

Many growing plant cells undergo rapid axial elongation with negligible radial expansion. Growth is driven by high internal turgor pressure causing viscous stretching of the cell wall, with embedded cellulose microfibrils providing the wall with strongly anisotropic properties. We present a theoretical model of a growing cell, representing the primary cell wall as a thin axisymmetric fibre-reinforced viscous sheet supported between rigid end plates. Asymptotic reduction of the governing equations, under simple sets of assumptions about the fibre and wall properties, yields variants of the traditional Lockhart equation, which relates the axial cell growth rate to the internal pressure. The model provides insights into the geometric and biomechanical parameters underlying bulk quantities such as wall extensibility, and shows how either dynamical changes in wall material properties or passive fibre reorientation may suppress cell elongation.

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