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 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.

scholarly journals Stable inheritance of Sinorhizobium meliloti cell growth polarity requires an FtsN-like protein and an amidase

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Elizaveta Krol ◽  
Lisa Stuckenschneider ◽  
Joana M. Kästle Silva ◽  
Peter L. Graumann ◽  
Anke Becker
Keyword(s):  
Cell Division ◽  
Cell Polarity ◽  
Chromosome Segregation ◽  
Cell Elongation ◽  
Sinorhizobium Meliloti ◽  
Growth Zone ◽  
Cell Pole ◽  
Growth Polarity ◽  
Selection Of

AbstractIn Rhizobiales bacteria, such as Sinorhizobium meliloti, cell elongation takes place only at new cell poles, generated by cell division. Here, we show that the role of the FtsN-like protein RgsS in S. meliloti extends beyond cell division. RgsS contains a conserved SPOR domain known to bind amidase-processed peptidoglycan. This part of RgsS and peptidoglycan amidase AmiC are crucial for reliable selection of the new cell pole as cell elongation zone. Absence of these components increases mobility of RgsS molecules, as well as abnormal RgsS accumulation and positioning of the growth zone at the old cell pole in about one third of the cells. These cells with inverted growth polarity are able to complete the cell cycle but show partially impaired chromosome segregation. We propose that amidase-processed peptidoglycan provides a landmark for RgsS to generate cell polarity in unipolarly growing Rhizobiales.

scholarly journals The Chaperonin GroESL Facilitates Caulobacter crescentus Cell Division by Supporting the Functions of the Z-Ring Regulators FtsA and FzlA

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Kristen Schroeder ◽  
Kristina Heinrich ◽  
Ines Neuwirth ◽  
Kristina Jonas
Keyword(s):  
Cell Cycle ◽  
Cell Wall ◽  
Cell Division ◽  
Bacterial Cell ◽  
Antimicrobial Agents ◽  
Caulobacter Crescentus ◽  
Content Type ◽  
Growing Cell ◽  
Z Ring ◽  
Bacterial Cell Cycle

ABSTRACT The highly conserved chaperonin GroESL performs a crucial role in protein folding; however, the essential cellular pathways that rely on this chaperone are underexplored. Loss of GroESL leads to severe septation defects in diverse bacteria, suggesting the folding function of GroESL may be integrated with the bacterial cell cycle at the point of cell division. Here, we describe new connections between GroESL and the bacterial cell cycle using the model organism Caulobacter crescentus. Using a proteomics approach, we identify candidate GroESL client proteins that become insoluble or are degraded specifically when GroESL folding is insufficient, revealing several essential proteins that participate in cell division and peptidoglycan biosynthesis. We demonstrate that other cell cycle events, such as DNA replication and chromosome segregation, are able to continue when GroESL folding is insufficient. We further find that deficiency of two FtsZ-interacting proteins, the bacterial actin homologue FtsA and the constriction regulator FzlA, mediate the GroESL-dependent block in cell division. Our data show that sufficient GroESL is required to maintain normal dynamics of the FtsZ scaffold and divisome functionality in C. crescentus. In addition to supporting divisome function, we show that GroESL is required to maintain the flow of peptidoglycan precursors into the growing cell wall. Linking a chaperone to cell division may be a conserved way to coordinate environmental and internal cues that signal when it is safe to divide. IMPORTANCE All organisms depend on mechanisms that protect proteins from misfolding and aggregation. GroESL is a highly conserved molecular chaperone that functions to prevent protein aggregation in organisms ranging from bacteria to humans. Despite detailed biochemical understanding of GroESL function, the in vivo pathways that strictly depend on this chaperone remain poorly defined in most species. This study provides new insights into how GroESL is linked to the bacterial cell division machinery, a crucial target of current and future antimicrobial agents. We identify a functional interaction between GroESL and the cell division proteins FzlA and FtsA, which modulate Z-ring function. FtsA is a conserved bacterial actin homologue, suggesting that as in eukaryotes, some bacteria exhibit a connection between cytoskeletal actin proteins and chaperonins. Our work further defines how GroESL is integrated with cell wall synthesis and illustrates how highly conserved folding machines ensure the functioning of fundamental cellular processes during stress.

scholarly journals Loss of PodJ in Agrobacterium tumefaciens Leads to Ectopic Polar Growth, Branching, and Reduced Cell Division

2016 ◽  
Vol 198 (13) ◽  
pp. 1883-1891 ◽  
Author(s):  
James C. Anderson-Furgeson ◽  
John R. Zupan ◽  
Romain Grangeon ◽  
Patricia C. Zambryski
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Agrobacterium Tumefaciens ◽  
Cell Envelope ◽  
Critical Factor ◽  
Polar Growth ◽  
Content Type ◽  
Growth Pole ◽  
Envelope Material ◽  
Z Ring

ABSTRACTAgrobacterium tumefaciensis a rod-shaped Gram-negative bacterium that elongates by unipolar addition of new cell envelope material. Approaching cell division, the growth pole transitions to a nongrowing old pole, and the division site creates new growth poles in sibling cells. TheA. tumefacienshomolog of theCaulobacter crescentuspolar organizing protein PopZ localizes specifically to growth poles. In contrast, theA. tumefacienshomolog of theC. crescentuspolar organelle development protein PodJ localizes to the old pole early in the cell cycle and accumulates at the growth pole as the cell cycle proceeds. FtsA and FtsZ also localize to the growth pole for most of the cell cycle prior to Z-ring formation. To further characterize the function of polar localizing proteins, we created a deletion ofA. tumefacienspodJ(podJAt). ΔpodJAtcells display ectopic growth poles (branching), growth poles that fail to transition to an old pole, and elongated cells that fail to divide. In ΔpodJAtcells,A. tumefaciensPopZ-green fluorescent protein (PopZAt-GFP) persists at nontransitioning growth poles postdivision and also localizes to ectopic growth poles, as expected for a growth-pole-specific factor. Even though GFP-PodJAtdoes not localize to the midcell in the wild type, deletion ofpodJAtimpacts localization, stability, and function of Z-rings as assayed by localization of FtsA-GFP and FtsZ-GFP. Z-ring defects are further evidenced by minicell production. Together, these data indicate that PodJAtis a critical factor for polar growth and that ΔpodJAtcells display a cell division phenotype, likely because the growth pole cannot transition to an old pole.IMPORTANCEHow rod-shaped prokaryotes develop and maintain shape is complicated by the fact that at least two distinct species-specific growth modes exist: uniform sidewall insertion of cell envelope material, characterized in model organisms such asEscherichia coli, and unipolar growth, which occurs in several alphaproteobacteria, includingAgrobacterium tumefaciens. Essential components for unipolar growth are largely uncharacterized, and the mechanism constraining growth to one pole of a wild-type cell is unknown. Here, we report that the deletion of a polar development gene,podJAt, results in cells exhibiting ectopic polar growth, including multiple growth poles and aberrant localization of cell division and polar growth-associated proteins. These data suggest that PodJAtis a critical factor in normal polar growth and impacts cell division inA. tumefaciens.

scholarly journals Agrobacterium tumefaciens Growth Pole Ring Protein: C Terminus and Internal Apolipoprotein Homologous Domains Are Essential for Function and Subcellular Localization

mBio ◽  
2021 ◽  
Vol 12 (3) ◽  
Author(s):  
John Zupan ◽  
Zisheng Guo ◽  
Trevor Biddle ◽  
Patricia Zambryski
Keyword(s):  
Amino Acids ◽  
Cell Wall ◽  
Agrobacterium Tumefaciens ◽  
Polar Growth ◽  
Content Type ◽  
Growth Pole ◽  
Human Apolipoprotein ◽  
Apolipoprotein A ◽  
C Terminus ◽  
Organizing Center

ABSTRACT The Agrobacterium growth pole ring (GPR) protein forms a hexameric ring at the growth pole (GP) that is essential for polar growth. GPR is large (2,115 amino acids) and contains 1,700 amino acids of continuous α-helices. To dissect potential GPR functional domains, we created deletions of regions with similarity to human apolipoprotein A-IV (396 amino acids), itself composed of α-helical domains. We also tested deletions of the GPR C terminus. Deletions were inducibly expressed as green fluorescent protein (GFP) fusion proteins and tested for merodiploid interference with wild-type (WT) GPR function, for partial function in cells lacking GPR, and for formation of paired fluorescent foci (indicative of hexameric rings) at the GP. Deletion of domains similar to human apolipoprotein A-IV in GPR caused defects in cell morphology when expressed in trans to WT GPR and provided only partial complementation to cells lacking GPR. Agrobacterium-specific domains A-IV-1 and A-IV-4 contain predicted coiled coil (CC) regions of 21 amino acids; deletion of CC regions produced severe defects in cell morphology in the interference assay. Mutants that produced the most severe effects on cell shape also failed to form paired polar foci. Modeling of A-IV-1 and A-IV-4 reveals significant similarity to the solved structure of human apolipoprotein A-IV. GPR C-terminal deletions profoundly blocked complementation. Finally, peptidoglycan (PG) synthesis is abnormally localized circumferentially in cells lacking GPR. The results support the hypothesis that GPR plays essential roles as an organizing center for membrane and PG synthesis during polar growth. IMPORTANCE Bacterial growth and division are extensively studied in model systems (Escherichia coli, Bacillus subtilis, and Caulobacter crescentus) that grow by dispersed insertion of new cell wall material along the length of the cell. An alternative growth mode—polar growth—is used by some Actinomycetales and Proteobacteria species. The latter phylum includes the family Rhizobiaceae, in which many species, including Agrobacterium tumefaciens, exhibit polar growth. Current research aims to identify growth pole (GP) factors. The Agrobacterium growth pole ring (GPR) protein is essential for polar growth and forms a striking hexameric ring structure at the GP. GPR is long (2,115 amino acids), and little is known about regions essential for structure or function. Genetic analyses demonstrate that the C terminus of GPR, and two internal regions with homology to human apolipoproteins (that sequester lipids), are essential for GPR function and localization to the GP. We hypothesize that GPR is an organizing center for membrane and cell wall synthesis during polar growth.

Wachstumsparameter in normalen und durch Actinomycin verlängerten Zellzyklen von Tetrahymena / Growth Parameters in Normal and Actinomycin-induced prolonged Cell Cycles of Tetrahymena

1969 ◽  
Vol 24 (12) ◽  
pp. 1624-1629 ◽  
Author(s):  
Günter Cleffmann
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Cell Division ◽  
Dna Replication ◽  
Cell Growth ◽  
Rna Synthesis ◽  
Growth Parameters ◽  
Average Duration ◽  
Cell Cycles ◽  
Growing Cell

Actinomycin in low concentration (0,2 μg/ml — 0,5 μg/ml) prolongs the average duration of the cell cycle of Tetrahymena considerably, but does not inhibit cell division completely. Some parameters of the growing cell have been tested in cell cycles extended in this way and compared to those of normally growing cells. The RNA synthesis of treated cells is reduced to such an extent that the RNA content per cell decreases during the prolonged cell cycle. Nevertheless cell growth, protein synthesis and DNA replication proceed at almost the same rate as in untreated cells. These findings indicate that the presence of actinomycin does not interfere with RNA fractions necessary for growth but reduce the synthesis of RNA fractions which are essential for cell division. Therefore a longer period is needed for their accumulation.

scholarly journals Cell-Biological Studies of Osmotic Shock Response in Streptomyces spp

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Katsuya Fuchino ◽  
Klas Flärdh ◽  
Paul Dyson ◽  
Nora Ausmees
Keyword(s):  
Cell Wall ◽  
Cell Polarity ◽  
Tip Growth ◽  
Biological Study ◽  
Polar Growth ◽  
Hyphal Branching ◽  
Content Type ◽  
Biological Studies ◽  
Wide Range ◽  
Tip Extension

ABSTRACT Most bacteria are likely to face osmotic challenges, but there is yet much to learn about how such environmental changes affect the architecture of bacterial cells. Here, we report a cell-biological study in model organisms of the genus Streptomyces, which are actinobacteria that grow in a highly polarized fashion to form branching hyphae. The characteristic apical growth of Streptomyces hyphae is orchestrated by protein assemblies, called polarisomes, which contain coiled-coil proteins DivIVA and Scy, and recruit cell wall synthesis complexes and the stress-bearing cytoskeleton of FilP to the tip regions of the hyphae. We monitored cell growth and cell-architectural changes by time-lapse microscopy in osmotic upshift experiments. Hyperosmotic shock caused arrest of growth, loss of turgor, and hypercondensation of chromosomes. The recovery period was protracted, presumably due to the dehydrated state of the cytoplasm, before hyphae could restore their turgor and start to grow again. In most hyphae, this regrowth did not take place at the original hyphal tips. Instead, cell polarity was reprogrammed, and polarisomes were redistributed to new sites, leading to the emergence of multiple lateral branches from which growth occurred. Factors known to regulate the branching pattern of Streptomyces hyphae, such as the serine/threonine kinase AfsK and Scy, were not involved in reprogramming of cell polarity, indicating that different mechanisms may act under different environmental conditions to control hyphal branching. Our observations of hyphal morphology during the stress response indicate that turgor and sufficient hydration of cytoplasm are required for Streptomyces tip growth. IMPORTANCE Polar growth is an intricate manner of growth for accomplishing a complicated morphology, employed by a wide range of organisms across the kingdoms of life. The tip extension of Streptomyces hyphae is one of the most pronounced examples of polar growth among bacteria. The expansion of the cell wall by tip extension is thought to be facilitated by the turgor pressure, but it was unknown how external osmotic change influences Streptomyces tip growth. We report here that severe hyperosmotic stress causes cessation of growth, followed by reprogramming of cell polarity and rearrangement of growth zones to promote lateral hyphal branching. This phenomenon may represent a strategy of hyphal organisms to avoid osmotic stress encountered by the growing hyphal tip.

scholarly journals Bacteriophage SP01 Gene Product 56 Inhibits Bacillus subtilis Cell Division by Interacting with FtsL and Disrupting Pbp2B and FtsW Recruitment

2020 ◽  
Vol 203 (2) ◽  
pp. e00463-20
Author(s):  
Amit Bhambhani ◽  
Isabella Iadicicco ◽  
Jules Lee ◽  
Syed Ahmed ◽  
Max Belfatto ◽  
...  
Keyword(s):  
Cell Wall ◽  
Bacillus Subtilis ◽  
Cell Division ◽  
Gene Product ◽  
Fluorescent Protein ◽  
Lytic Bacteriophage ◽  
Cell Wall Synthesis ◽  
Content Type ◽  
Ftsz Ring ◽  
Green Fluorescent

ABSTRACTPrevious work identified gene product 56 (gp56), encoded by the lytic bacteriophage SP01, as being responsible for inhibition of Bacillus subtilis cell division during its infection. Assembly of the essential tubulin-like protein FtsZ into a ring-shaped structure at the nascent site of cytokinesis determines the timing and position of division in most bacteria. This FtsZ ring serves as a scaffold for recruitment of other proteins into a mature division-competent structure permitting membrane constriction and septal cell wall synthesis. Here, we show that expression of the predicted 9.3-kDa gp56 of SP01 inhibits later stages of B. subtilis cell division without altering FtsZ ring assembly. Green fluorescent protein-tagged gp56 localizes to the membrane at the site of division. While its localization does not interfere with recruitment of early division proteins, gp56 interferes with the recruitment of late division proteins, including Pbp2b and FtsW. Imaging of cells with specific division components deleted or depleted and two-hybrid analyses suggest that gp56 localization and activity depend on its interaction with FtsL. Together, these data support a model in which gp56 interacts with a central part of the division machinery to disrupt late recruitment of the division proteins involved in septal cell wall synthesis.IMPORTANCE Studies over the past decades have identified bacteriophage-encoded factors that interfere with host cell shape or cytokinesis during viral infection. The phage factors causing cell filamentation that have been investigated to date all act by targeting FtsZ, the conserved prokaryotic tubulin homolog that composes the cytokinetic ring in most bacteria and some groups of archaea. However, the mechanisms of several phage factors that inhibit cytokinesis, including gp56 of bacteriophage SP01 of Bacillus subtilis, remain unexplored. Here, we show that, unlike other published examples of phage inhibition of cytokinesis, gp56 blocks B. subtilis cell division without targeting FtsZ. Rather, it utilizes the assembled FtsZ cytokinetic ring to localize to the division machinery and to block recruitment of proteins needed for septal cell wall synthesis.

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.

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