Article

Assembly dynamics of Mycobacterium tuberculosis FtsZ

Department of Cell Biology, Duke University, Medical Center, Durham, North Carolina 27710, USA.
Journal of Biological Chemistry (Impact Factor: 4.57). 10/2007; 282(38):27736-43. DOI: 10.1074/jbc.M703788200
Source: PubMed

ABSTRACT We have investigated the assembly of FtsZ from Mycobacterium tuberculosis (MtbFtsZ). Electron microscopy confirmed the previous observation that MtbFtsZ assembled into long, two-stranded filaments at pH 6.5. However, we found that assembly at pH 7.2 or 7.7 produced predominantly short, one-stranded protofilaments, similar to those of Escherichia coli FtsZ (EcFtsZ). Near pH 7, which is close to the pH of M. tuberculosis cytoplasm, MtbFtsZ formed a mixture of single- and two-stranded filaments. We developed a fluorescence resonance energy transfer assay to measure the kinetics of initial assembly and the dynamic properties at steady state. Assembly of MtbFtsZ reached a plateau after 60-100 s, about 10 times slower than EcFtsZ. The initial assembly kinetics were similar at pH 6.5 and 7.7, despite the striking difference in the polymer structures. Both were fit with a cooperative assembly mechanism involving a weak dimer nucleus, similar to EcFtsZ but with slower kinetics. Subunit turnover and GTPase at steady state were also about 10 times slower for MtbFtsZ than for EcFtsZ. Specifically, the half-time for subunit turnover in vitro at pH 7.7 was 42 s for MtbFtsZ compared with 5.5 s for EcFtsZ. Photobleaching studies in vivo showed a range of turnover half-times with an average of 25 s for MtbFtsZ as compared with 9 s for EcFtsZ.

Download full-text

Full-text

Available from: Yaodong Chen, Aug 23, 2014
0 Followers
 · 
153 Views
 · 
19 Downloads
  • Source
    • "Through this simple mechanism, which is basically energy neutral, we believe that the Zring is constantly exerting a constriction force on the membrane and that constriction finally occurs when the peptidoglycan remodeling permits the wall to follow this force [M€ oll et al., 2010]. A constant constriction force is consistent with the high turnover of FtsZ observed by F€ orster resonance energy transfer (FRET) [Chen et al., 2005, 2007]. Other FtsZ associated proteins may further fine tune the operation [Peters et al., 2007]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: All cells, from simple bacteria to complex human tissues, rely on extensive networks of protein fibers to help maintain their proper form and function. These filament systems usually do not operate as single filaments, but form complex suprastructures, which are essential for specific cellular functions. Here, we describe the progress in determining the architectures of molecular filamentous suprastructures, the principles leading to their formation, and the mechanisms by which they may facilitate function. The complex eukaryotic cytoskeleton is tightly regulated by a large number of actin- or microtubule-associated proteins. In contrast, recently discovered bacterial actins and tubulins have few associated regulatory proteins. Hence, the quest to find basic principles that govern the formation of filamentous suprastructures is simplified in bacteria. Three common principles, which have been probed extensively during evolution, can be identified that lead to suprastructures formation: cationic counterion fluctuations; self-association into liquid crystals; and molecular crowding. The underlying physics of these processes will be discussed with respect to physiological circumstance.
    Cytoskeleton 02/2012; 69(2):71-87. DOI:10.1002/cm.21006 · 3.01 Impact Factor
  • Source
    • "This is consistent with the absence of spatial regulation by Min system in mycobacteria. However, the FtsZ ring is still the determinant in establishing division site as previously reported (Dziadek et al. 2003; Chen et al. 2007). Despite either the asymmetric or random selection of the division site, the completion of division of mycobacteria produces predominantly normal sized cells with an intact genome content (in the absence of any nucleoidocclusion function). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacteria have the ability to adapt to different growth conditions and to survive in various environments. They have also the capacity to enter into dormant states and some bacteria form spores when exposed to stresses such as starvation and oxygen deprivation. Sporulation has been demonstrated in a number of different bacteria but Mycobacterium spp. have been considered to be non-sporulating bacteria. We recently provided evidence that Mycobacterium marinum and likely also Mycobacterium bovis bacillus Calmette-Guérin can form spores. Mycobacterial spores were detected in old cultures and our findings suggest that sporulation might be an adaptation of lifestyle for mycobacteria under stress. Here we will discuss our current understanding of growth, cell division, and sporulation in mycobacteria.
    Antonie van Leeuwenhoek 05/2010; 98(2):165-77. DOI:10.1007/s10482-010-9446-0 · 2.14 Impact Factor
  • Source
    • "MtFtsZ has been reported to display a reduced GTPase activity (White et al. 2000) and a concomitant reduction in the rate of filament turnover in vivo (Chen et al. 2007). Consistently, rings and cables of MtFtsZ displayed a significant increase in t 1/2 in FRAP experiments (Fig. 1D,E; Supplemental Table 1), suggesting that MtFtsZ was potentially using similar mechanisms of assembly and polymerization in fission yeast. "
    [Show abstract] [Hide abstract]
    ABSTRACT: During cytokinesis, most bacteria assemble a ring-like structure that is composed of the tubulin homolog FtsZ. The mechanisms regulating assembly and organization of FtsZ molecules into rings are not fully understood. Here, we express bacterial FtsZ in the fission yeast Schizosaccharomyces pombe and find that FtsZ filaments assemble into cytoplasmic rings. Investigation of the Escherichia coli FtsZ revealed that ring assembly occurred by a process of closure and/or spooling of linear bundles. We conclude that FtsZ rings can assemble in the absence of all other bacterial cytokinetic proteins and that the process might involve hydrolysis of FtsZ-bound GTP and lateral associations between FtsZ filaments.
    Genes & Development 08/2008; 22(13):1741-6. DOI:10.1101/gad.1660908 · 12.64 Impact Factor
Show more