scholarly journals Simulations of proposed mechanisms of FtsZ-driven cell constriction

2019 ◽  
Author(s):  
Lam T. Nguyen ◽  
Catherine M. Oikonomou ◽  
Grant J. Jensen
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Recent Observation ◽  
Turgor Pressure ◽  
Critical Conditions ◽  
Bacterial Cell Division ◽  
Division Plane ◽  
Lateral Contact ◽  
Rigid Connection

ABSTRACTTo divide, bacteria must constrict their membranes against significant force from turgor pressure. A tubulin homo-log, FtsZ, is thought to drive constriction, but how FtsZ filaments might generate constrictive force in the absence of motor proteins is not well understood. There are two predominant models in the field. In one, filaments overlap to form complete rings around the circumference of the cell; as filaments slide against each other to maximize lateral contact, the rings constrict. In the other, filaments exert force on the membrane by a GTP-hydrolysis-induced switch in conformation from straight to bent. Here we developed software, ZCONSTRICT, for quantitative 3D simulations of Gram-negative bacterial cell division to test these two models and identify critical conditions required for them to work. We find that the avidity of lateral interactions quickly halts the sliding of filaments, so a mechanism such as depolymerization or treadmilling is required to sustain constriction by filament sliding. For filament bending, we find that a mechanism such as the presence of a rigid linker is required to constrain bending within the division plane and maintain the distance observed in vivo between the filaments and the membrane. We also explored the recent observation of constriction associated with a single FtsZ filament and found that it can be explained by the filament bending model if there is a rigid connection between the filament and the cell wall. Together, our work sheds light on the physical principles underlying bacterial cell division and informs future experiments to elucidate the mechanism of FtsZ.

scholarly journals Simulations of Proposed Mechanisms of FtsZ-Driven Cell Constriction

2020 ◽  
Vol 203 (3) ◽  
Author(s):  
Lam T. Nguyen ◽  
Catherine M. Oikonomou ◽  
Grant J. Jensen
Keyword(s):  
Recent Observation ◽  
Turgor Pressure ◽  
Three Dimensional ◽  
The Other ◽  
Critical Conditions ◽  
Bacterial Cell Division ◽  
Division Plane ◽  
3D Simulations ◽  
Lateral Contact

ABSTRACT To divide, bacteria must constrict their membranes against significant force from turgor pressure. A tubulin homolog, FtsZ, is thought to drive constriction, but how FtsZ filaments might generate constrictive force in the absence of motor proteins is not well understood. There are two predominant models in the field. In one, FtsZ filaments overlap to form complete rings around the circumference of the cell, and attractive forces cause filaments to slide past each other to maximize lateral contact. In the other, filaments exert force on the membrane by a GTP-hydrolysis-induced switch in conformation from straight to bent. Here, we developed software, ZCONSTRICT, for quantitative three-dimensional (3D) simulations of Gram-negative bacterial cell division to test these two models and identify critical conditions required for them to work. We find that the avidity of any kind of lateral interactions quickly halts the sliding of filaments, so a mechanism such as depolymerization or treadmilling is required to sustain constriction by filament sliding. For filament bending, we find that a mechanism such as the presence of a rigid linker is required to constrain bending to within the division plane and maintain the distance observed in vivo between the filaments and the membrane. Of these two models, only the filament bending model is consistent with our lab’s recent observation of constriction associated with a single, short FtsZ filament. IMPORTANCE FtsZ is thought to generate constrictive force to divide the cell, possibly via one of two predominant models in the field. In one, FtsZ filaments overlap to form complete rings which constrict as filaments slide past each other to maximize lateral contact. In the other, filaments exert force on the membrane by switching conformation from straight to bent. Here, we developed software, ZCONSTRICT, for three-dimensional (3D) simulations to test these two models. We find that a mechanism such as depolymerization or treadmilling are required to sustain constriction by filament sliding. For filament bending, we find that a mechanism that constrains bending to within the division plane is required to maintain the distance observed in vivo between the filaments and the membrane.

scholarly journals Lateral interactions between protofilaments of the bacterial tubulin homolog FtsZ are essential for cell division

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Fenghui Guan ◽  
Jiayu Yu ◽  
Jie Yu ◽  
Yang Liu ◽  
Ying Li ◽  
...  
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Dynamic Structure ◽  
Living Cells ◽  
Lateral Interactions ◽  
Bacterial Cell Division ◽  
Z Ring ◽  
Crystallographic Structures ◽  
Order Structures

The prokaryotic tubulin homolog FtsZ polymerizes into protofilaments, which further assemble into higher-order structures at future division sites to form the Z-ring, a dynamic structure essential for bacterial cell division. The precise nature of interactions between FtsZ protofilaments that organize the Z-ring and their physiological significance remain enigmatic. In this study, we solved two crystallographic structures of a pair of FtsZ protofilaments, and demonstrated that they assemble in an antiparallel manner through the formation of two different inter-protofilament lateral interfaces. Our in vivo photocrosslinking studies confirmed that such lateral interactions occur in living cells, and disruption of the lateral interactions rendered cells unable to divide. The inherently weak lateral interactions enable FtsZ protofilaments to self-organize into a dynamic Z-ring. These results have fundamental implications for our understanding of bacterial cell division and for developing antibiotics that target this key process.

scholarly journals Asymmetric localization of the cell division machinery during Bacillus subtilis sporulation

2020 ◽  
Author(s):  
Kanika Khanna ◽  
Javier López-Garrido ◽  
Joseph Sugie ◽  
Kit Pogliano ◽  
Elizabeth Villa
Keyword(s):  
Bacillus Subtilis ◽  
Cell Division ◽  
Vegetative Growth ◽  
Bacterial Cell ◽  
Mother Cell ◽  
Electron Tomography ◽  
Leading Edge ◽  
Specific Protein ◽  
Bacterial Cell Division ◽  
Division Plane

The mechanistic details of bacterial cell division are poorly understood. The Gram-positive bacterium Bacillus subtilis can divide via two modes. During vegetative growth, the division septum is formed at the mid cell to produce two equal daughter cells. However, during sporulation, the division septum is formed closer to one pole to yield a smaller forespore and a larger mother cell. We use cryo-electron tomography to visualize the architectural differences in the organization of FtsAZ filaments, the major orchestrators of bacterial cell division during these conditions. We demonstrate that during vegetative growth, FtsAZ filaments are present uniformly around the leading edge of the invaginating septum but during sporulation, they are only present on the mother cell side. Our data show that the sporulation septum is thinner than the vegetative septum during constriction, and that this correlates with half as many FtsZ filaments tracking the division plane during sporulation as compared to vegetative growth. We further find that a sporulation-specific protein, SpoIIE, regulates divisome localization and septal thickness during sporulation. Our data provide first evidence of asymmetric localization of the cell division machinery, and not just septum formation, to produce different cell types with diverse fates in bacteria.

scholarly journals A Specialized Peptidoglycan Synthase Promotes Salmonella Cell Division inside Host Cells

mBio ◽  
2017 ◽  
Vol 8 (6) ◽  
Author(s):  
Sónia Castanheira ◽  
Juan J. Cestero ◽  
Gadea Rico-Pérez ◽  
Pablo García ◽  
Felipe Cava ◽  
...  
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Salmonella Enterica ◽  
Bacterial Pathogens ◽  
Bacterial Cell Division ◽  
Daughter Cells ◽  
Target Organs ◽  
A Cell ◽  
Acidic Environments

ABSTRACT Bacterial cell division has been studied extensively under laboratory conditions. Despite being a key event in the bacterial cell cycle, cell division has not been explored in vivo in bacterial pathogens interacting with their hosts. We discovered in Salmonella enterica serovar Typhimurium a gene absent in nonpathogenic bacteria and encoding a peptidoglycan synthase with 63% identity to penicillin-binding protein 3 (PBP3). PBP3 is an essential cell division-specific peptidoglycan synthase that builds the septum required to separate daughter cells. Since S. Typhimurium carries genes that encode a PBP3 paralog—which we named PBP3SAL—and PBP3, we hypothesized that there are different cell division events in host and nonhost environments. To test this, we generated S. Typhimurium isogenic mutants lacking PBP3SAL or the hitherto considered essential PBP3. While PBP3 alone promotes cell division under all conditions tested, the mutant producing only PBP3SAL proliferates under acidic conditions (pH ≤ 5.8) but does not divide at neutral pH. PBP3SAL production is tightly regulated with increased levels as bacteria grow in media acidified up to pH 4.0 and in intracellular bacteria infecting eukaryotic cells. PBP3SAL activity is also strictly dependent on acidic pH, as shown by beta-lactam antibiotic binding assays. Live-cell imaging microscopy revealed that PBP3SAL alone is sufficient for S. Typhimurium to divide within phagosomes of the eukaryotic cell. Additionally, we detected much larger amounts of PBP3SAL than those of PBP3 in vivo in bacteria colonizing mouse target organs. Therefore, PBP3SAL evolved in S. Typhimurium as a specialized peptidoglycan synthase promoting cell division in the acidic intraphagosomal environment. IMPORTANCE During bacterial cell division, daughter cells separate by a transversal structure known as the division septum. The septum is a continuum of the cell wall and therefore is composed of membrane(s) and a peptidoglycan layer. To date, actively growing bacteria were reported to have only a “cell division-specific” peptidoglycan synthase required for the last steps of septum formation and consequently, essential for bacterial life. Here, we discovered that Salmonella enterica has two peptidoglycan synthases capable of synthesizing the division septum. One of these enzymes, PBP3SAL, is present only in bacterial pathogens and evolved in Salmonella to function exclusively in acidic environments. PBP3SAL is used preferentially by Salmonella to promote cell division in vivo in mouse target organs and inside acidified phagosomes. Our data challenge the concept of only one essential cell division-specific peptidoglycan synthase and demonstrate that pathogens can divide in defined host locations using alternative mechanisms. IMPORTANCE During bacterial cell division, daughter cells separate by a transversal structure known as the division septum. The septum is a continuum of the cell wall and therefore is composed of membrane(s) and a peptidoglycan layer. To date, actively growing bacteria were reported to have only a “cell division-specific” peptidoglycan synthase required for the last steps of septum formation and consequently, essential for bacterial life. Here, we discovered that Salmonella enterica has two peptidoglycan synthases capable of synthesizing the division septum. One of these enzymes, PBP3SAL, is present only in bacterial pathogens and evolved in Salmonella to function exclusively in acidic environments. PBP3SAL is used preferentially by Salmonella to promote cell division in vivo in mouse target organs and inside acidified phagosomes. Our data challenge the concept of only one essential cell division-specific peptidoglycan synthase and demonstrate that pathogens can divide in defined host locations using alternative mechanisms.

scholarly journals The chaperonin GroESL facilitates Caulobacter crescentus cell division by supporting the function of the actin homologue FtsA

2020 ◽  
Author(s):  
Kristen Schroeder ◽  
Kristina Heinrich ◽  
Ines Neuwirth ◽  
Kristina Jonas
Keyword(s):  
Cell Cycle ◽  
Cell Wall ◽  
Cell Division ◽  
Bacterial Cell ◽  
Antimicrobial Agents ◽  
Caulobacter Crescentus ◽  
Bacterial Cell Division ◽  
Growing Cell ◽  
Bacterial Cell Cycle

AbstractThe 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, and find that deficiency of the bacterial actin homologue FtsA function mediates the GroESL-dependent block in cell division. Our data suggest that a GroESL-FtsA interaction is required to maintain normal dynamics of the FtsZ scaffold and divisome functionality in C. crescentus. In addition to supporting FtsA 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.ImportanceAll 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 FtsA, 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 Structural analysis of the interaction between the bacterial cell division proteins FtsQ and FtsB

2018 ◽  
Author(s):  
Danguole Kureisaite-Ciziene ◽  
Aravindan Varadajan ◽  
Stephen H. McLaughlin ◽  
Marjolein Glas ◽  
Alejandro Montón Silva ◽  
...  
Keyword(s):  
Cell Division ◽  
Membrane Proteins ◽  
Bacterial Cell ◽  
Outer Membrane Proteins ◽  
Ring Structure ◽  
Globular Domain ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Division Process

AbstractMost bacteria and archaea use similar proteins within their cell division machinery, which uses the tubulin homologue FtsZ as its central organiser. In Gram-negative Escherichia coli bacteria, FtsZ recruits cytosolic, transmembrane, periplasmic and outer membrane proteins, assembling the divisome that facilitates bacterial cell division. One such divisome component, FtsQ, a bitopic membrane protein with a globular domain in the periplasm, has been shown to interact with many other divisome proteins. Despite its otherwise unknown function, it has been shown to be a major divisome interaction hub. Here, we investigated the interactions of FtsQ with FtsB and FtsL, two small bitopic membrane proteins that act immediately downstream of FtsQ. In biochemical assays we show that the periplasmic domains of E. coli FtsB and FtsL interact with FtsQ, but not with each other. Our crystal structure of FtsB bound to the β domain of FtsQ shows that only residues 64-87 of FtsB interact with FtsQ. A synthetic peptide comprising those 24 FtsB residues recapitulates the FtsQ:FtsB interactions. Protein deletions and structure-guided mutant analyses validate the structure. Furthermore, the same structure-guided mutants show cell division defects in vivo that are consistent with our structure of the FtsQ:FtsB complex that shows their interactions as they occur during cell division. Our work provides intricate details of the interactions within the divisome and also provides a tantalising view of a highly conserved protein interaction in the periplasm of bacteria that is an excellent target for cell division inhibitor searches.ImportanceCells in most bacteria and archaea divide through a cell division process that is characterised through its filamentous organiser, FtsZ protein. FtsZ forms a ring structure at the division site and starts the recruitment of 10-20 downstream proteins that together form an elusive multi-protein complex termed divisome. The divisome is thought to facilitate many of the steps required to make two cells out of one. FtsQ and FtsB are part of the divisome, with FtsQ being a central hub, interacting with most of the other divisome components. Here we show for the first time how FtsQ interacts with its downstream partner FtsB and show that mutations that disturb the interface between the two proteins effectively inhibit cell division.

scholarly journals Treadmilling by FtsZ filaments drives peptidoglycan synthesis and bacterial cell division

2016 ◽  
Author(s):  
Alexandre W. Bisson Filho ◽  
Yen-Pang Hsu ◽  
Georgia R. Squyres ◽  
Erkin Kuru ◽  
Fabai Wu ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Division ◽  
Division Ring ◽  
Bacterial Cell ◽  
Cytoplasmic Membrane ◽  
Bacterial Cell Division ◽  
Cell Wall Synthesis ◽  
Division Plane ◽  
Peptidoglycan Synthesis

AbstractHow bacteria produce a septum to divide in two is not well understood. This process is mediated by periplasmic cell-wall producing enzymes that are positioned by filaments of the cytoplasmic membrane-associated actin FtsA and the tubulin FtsZ (FtsAZ). To understand how these components act in concert to divide cells, we visualized their movements relative to the dynamics of cell wall synthesis during cytokinesis. We find that the division septum is built at discrete sites that move around the division plane. Furthermore, FtsAZ filaments treadmill in circumferential paths around the division ring, pulling along the associated cell-wall-synthesizing enzymes. We show that the rate of FtsZ treadmilling controls both the rate of cell wall synthesis and cell division. The coupling of both the position and activity of the cell wall synthases to FtsAZ treadmilling guides the progressive insertion of new cell wall, synthesizing increasingly small concentric rings to divide the cell.One-sentence summaryBacterial cytokinesis is controlled by circumferential treadmilling of FtsAZ filaments that drives the insertion of new cell wall.

scholarly journals In Vivo Imaging of a Bacterial Cell Division Protein Using a Protease-Assisted Small-Molecule Labeling Approach

ChemBioChem ◽  
2008 ◽  
Vol 9 (5) ◽  
pp. 677-680 ◽  
Author(s):  
Souvik Chattopadhaya ◽  
Farhana B. Abu Bakar ◽  
Rajavel Srinivasan ◽  
Shao. Q. Yao
Keyword(s):  
Cell Division ◽  
Small Molecule ◽  
In Vivo Imaging ◽  
Bacterial Cell ◽  
Bacterial Cell Division ◽  
Cell Division Protein ◽  
Labeling Approach
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