Energetics and Geometry of FtsZ Polymers: Nucleated Self-Assembly of Single Protofilaments

Huecas, Sonia; Llorca, Óscar; Boskovic, Jasminka; Martín‐Benito, Jaime; Valpuesta, José M.; Andreu, José Manuel

doi:10.1529/biophysj.107.115493

Cited by 110 publications

(159 citation statements)

References 85 publications

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“…S5). Confinement of these clusters to a ∼60 × 100 nm Z-ring crosssection in vivo (SI Appendix, Table S1) indicates that FtsZ protofilaments in Z-ring clusters typically do not grow longer than 100 nm in any direction, which is within the 100-to 200-nm range of protofilament lengths observed in vitro (64)(65)(66) and consistent with random orientations of FtsZ protofilaments in the Z-ring (67).…”

Section: Resultsmentioning

confidence: 54%

Defining the rate-limiting processes of bacterial cytokinesis

Coltharp

Buss

Plumer

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

161

216

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Bacterial cytokinesis is accomplished by the essential ‘divisome’ machinery. The most widely conserved divisome component, FtsZ, is a tubulin homolog that polymerizes into the ‘FtsZ-ring’ (‘Z-ring’). Previous in vitro studies suggest that Z-ring contraction serves as a major constrictive force generator to limit the progression of cytokinesis. Here, we applied quantitative superresolution imaging to examine whether and how Z-ring contraction limits the rate of septum closure during cytokinesis in Escherichia coli cells. Surprisingly, septum closure rate was robust to substantial changes in all Z-ring properties proposed to be coupled to force generation: FtsZ’s GTPase activity, Z-ring density, and the timing of Z-ring assembly and disassembly. Instead, the rate was limited by the activity of an essential cell wall synthesis enzyme and further modulated by a physical divisome–chromosome coupling. These results challenge a Z-ring–centric view of bacterial cytokinesis and identify cell wall synthesis and chromosome segregation as limiting processes of cytokinesis.

show abstract

Section: Resultsmentioning

confidence: 54%

Defining the rate-limiting processes of bacterial cytokinesis

Coltharp

Buss

Plumer

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

161

216

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“…1F. In the presence of GTP in vitro, FtsZ either forms straight filaments with little curvature (14), or filaments with intermediate curvature with radii on the order of 100 nm (30)(31)(32)(33). The modeled GTP-FtsZ filament in Fig.…”

Section: Discussionmentioning

confidence: 99%

Nucleotide-dependent conformations of FtsZ dimers and force generation observed through molecular dynamics simulations

Hsin

Gopinathan

Huang

2012

Proc. Natl. Acad. Sci. U.S.A.

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The bacterial cytoskeletal protein FtsZ is a GTPase that is thought to provide mechanical constriction force via an unidentified mechanism. Purified FtsZ polymerizes into filaments with varying structures in vitro: while GTP-bound FtsZ assembles into straight or gently curved filaments, GDP-bound FtsZ forms highly curved filaments, prompting the hypothesis that a difference in the inherent curvature of FtsZ filaments provides mechanical force. However, no nucleotide-dependent structural transition of FtsZ monomers has been observed to support this force generation model. Here, we present a series of all-atom molecular dynamics simulations probing the effects of nucleotide binding on the structure of an FtsZ dimer. We found that the FtsZ-dimer structure is dependent on nucleotidebinding state. While a GTP-bound FtsZ dimer retained a firm monomer-monomer contact, a GDP-bound FtsZ dimer lost some of the monomer-monomer association, leading to a "hinge-opening" event that resulted in a more bent dimer, while leaving each monomer structure largely unaffected. We constructed models of FtsZ filaments and found that a GDP-FtsZ filament is much more curved than a GTP-FtsZ filament, with the degree of curvature matching prior experimental data. FtsZ dynamics were used to estimate the amount of force an FtsZ filament could exert when hydrolysis occurs (20-30 pN per monomer). This magnitude of force is sufficient to direct inward cell-wall growth during division, and to produce the observed degree of membrane pinching in liposomes. Taken together, our data provide molecular-scale insight on the origin of FtsZ-based constriction force, and the mechanism underlying prokaryotic cell division.bacterial cell division | bacterial cytoskeleton | GTP hydrolysis T he bacterial cell-division protein FtsZ, a tubulin homolog and a GTPase, polymerizes into filaments situated underneath the cytoplasmic membrane at the division site (1-3). The ftsz gene is essential and depletion of FtsZ protein leads to cells unable to divide that instead take on a filamentous morphology (4). During division, rod-shaped bacteria such as Escherichia coli synthesize new hemispherical membrane and cell wall, requiring inward forces. While an array of proteins are needed for division to occur (5, 6), FtsZ alone has been demonstrated to be sufficient for generating inward pinching forces on liposomes in vitro (7-10), and is thought to be the source of the constriction force needed for division.How FtsZ generates mechanical force is still unclear, but several models have been proposed (11), one of which is based on the intrinsic nucleotide-dependent bending of FtsZ filaments (12, 13). In the presence of GTP, purified FtsZ assembles into either straight or gently curved filaments with a radius of curvature of approximately 100 nm, while in the presence of GDP, highly curved filaments form with a radius of curvature of approximately 10 nm (12,14,15). Subsequent theoretical modeling demonstrated that the rapid transition between straight and curved FtsZ filaments...

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“…[1][2][3]. Purified bacterial FtsZ undergoes GTP-dependent, hydrolysis-independent polymerization primarily into single protofilaments (4,5), but protofilament sheets and bundles form in the presence of stabilizing agents that promote lateral interactions (6 -8). Polymerization stimulates FtsZ GTPase activity because the catalytic site for GTP hydrolysis lies in the longitudinal interface between adjacent monomers within the polymer (9).…”

mentioning

confidence: 99%

GTP-dependent Heteropolymer Formation and Bundling of Chloroplast FtsZ1 and FtsZ2

Olson

Wang

Osteryoung

2010

Journal of Biological Chemistry

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Bacteria and chloroplasts require the ring-forming cytoskeletal protein FtsZ for division. Although bacteria accomplish division with a single FtsZ, plant chloroplasts require two FtsZ types for division, FtsZ1 and FtsZ2. These proteins colocalize to a mid-plastid Z ring, but their biochemical relationship is poorly understood. We investigated the in vitro behavior of recombinant FtsZ1 and FtsZ2 separately and together. Both proteins bind and hydrolyze GTP, although GTPase activities are low compared with the activity of Escherichia coli FtsZ. Each protein undergoes GTP-dependent assembly into thin protofilaments in the presence of calcium as a stabilizing agent, similar to bacterial FtsZ. In contrast, when mixed without calcium, FtsZ1 and FtsZ2 exhibit slightly elevated GTPase activity and coassembly into extensively bundled protofilaments. Coassembly is enhanced by FtsZ1, suggesting that it promotes lateral interactions between protofilaments. Experiments with GTPase-deficient mutants reveal that FtsZ1 and FtsZ2 form heteropolymers. Maximum coassembly occurs in reactions containing equimolar FtsZ1 and FtsZ2, but significant coassembly occurs at other stoichiometries. The FtsZ1:FtsZ2 ratio in coassembled structures mirrors their input ratio, suggesting plasticity in protofilament and/or bundle composition. This behavior contrasts with that of ␣-and ␤-tubulin and the bacterial tubulin-like proteins BtubA and BtubB, which coassemble in a strict 1:1 stoichiometry. Our findings raise the possibility that plasticity in FtsZ filament composition and heteropolymerization-induced bundling could have been a driving force for the coevolution of FtsZ1 and FtsZ2 in the green lineage, perhaps arising from an enhanced capacity for the regulation of Z ring composition and activity in vivo.Cell division in bacteria and chloroplast division in plants both require FtsZ, a tubulin-like GTPase that functions as a contractile ring, the Z ring, inside the cell or chloroplast. Mutations in bacterial FtsZ genes disrupt cell division, resulting in long filamented cells (reviewed in Refs. 1-3). Purified bacterial FtsZ undergoes GTP-dependent, hydrolysis-independent polymerization primarily into single protofilaments (4, 5), but protofilament sheets and bundles form in the presence of stabilizing agents that promote lateral interactions (6 -8). Polymerization stimulates FtsZ GTPase activity because the catalytic site for GTP hydrolysis lies in the longitudinal interface between adjacent monomers within the polymer (9). GTP hydrolysis destabilizes protofilaments, leading to disassembly (10). The in vivo structure of the bacterial Z ring is not yet clear, but recent models suggest it may be built from short overlapping protofilaments that are stabilized at the division site by accessory factors (11, 12). The Z ring functions partly as a scaffold for other cell division proteins and recently has also been shown to provide contractile force for membrane constriction (13,14).In most bacteria, including the cyanobacterial relatives of chloropl...

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Energetics and Geometry of FtsZ Polymers: Nucleated Self-Assembly of Single Protofilaments

Cited by 110 publications

References 85 publications

Defining the rate-limiting processes of bacterial cytokinesis

Defining the rate-limiting processes of bacterial cytokinesis

Nucleotide-dependent conformations of FtsZ dimers and force generation observed through molecular dynamics simulations

GTP-dependent Heteropolymer Formation and Bundling of Chloroplast FtsZ1 and FtsZ2

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