Article

A Spindle-Like Apparatus Guides Bacterial Chromosome Segregation

Department of Developmental Biology, Stanford University School of Medicine, Beckman Center, Stanford, CA 94305, USA.
Nature Cell Biology (Impact Factor: 20.06). 08/2010; 12(8):791-8. DOI: 10.1038/ncb2083
Source: PubMed

ABSTRACT Until recently, a dedicated mitotic apparatus that segregates newly replicated chromosomes into daughter cells was believed to be unique to eukaryotic cells. Here we demonstrate that the bacterium Caulobacter crescentus segregates its chromosome using a partitioning (Par) apparatus that has surprising similarities to eukaryotic spindles. We show that the C. crescentus ATPase ParA forms linear polymers in vitro and assembles into a narrow linear structure in vivo. The centromere-binding protein ParB binds to and destabilizes ParA structures in vitro. We propose that this ParB-stimulated ParA depolymerization activity moves the centromere to the opposite cell pole through a burnt bridge Brownian ratchet mechanism. Finally, we identify the pole-specific TipN protein as a new component of the Par system that is required to maintain the directionality of DNA transfer towards the new cell pole. Our results elucidate a bacterial chromosome segregation mechanism that features basic operating principles similar to eukaryotic mitotic machines, including a multivalent protein complex at the centromere that stimulates the dynamic disassembly of polymers to move chromosomes into daughter compartments.

Download full-text

Full-text

Available from: Ethan Clark Garner, Dec 28, 2013
0 Followers
 · 
122 Views
  • Source
    • "Cholesterol inactivation was obtained by preincubating cells with filipin for 30 min at the concentration of 12 lg/ml or MbDC with a preincubation of 30 min at the concentration of 5 mM, while actin microfilaments disruption was performed by preincubating for 30 min with cytochalasin D at the concentration of 2 lM. determine the ParA and ParB dynamics, suggesting that retracting ParA fibers are critical for this phenomenon [40]. SMLM also has shown its applicability in providing new details into viral infection. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Single molecule localization microscopy(SMLM), providing up to an order of magnitude improvement in spatial resolution over conventional fluorescence microscopy, has the potential to be a highly useful tool for quantitative biological experiments. It has already been used for this purpose in varied fields in biology, ranging from molecular biology to neuroscience. In this review article, we briefly review the applications of SMLM in quantitative biology, and also the challenges involved and some of the solutions that have been proposed. Due to its advantages in labeling specificity and the relatively low overcounting caused by photoblinking when PhotoActivable Fluorescent Proteins are used as labels, we focus on Photoactivation Localization Microscopy(PALM), even though the ideas presented might be applicable to SMLM in general. Also, we focus on the following three quantitative measurements: single molecule counting, analysis of protein spatial distribution heterogeneity and co-localization analysis.
    FEBS Letters 10/2014; 588(19). DOI:10.1016/j.febslet.2014.06.014 · 3.34 Impact Factor
  • Source
    • "A microtubule-based apparatus called the mitotic spindle conducts genome segregation during eukaryotic cell division. Bacterial cells (with some exceptions (Ptacin et al. 2010)) do not have mitotic spindle. While in fission and budding yeasts nuclear envelopes remain intact, the envelopes in animal cells break down during mitosis (open mitosis) 174 A. Mashaghi, C. Dekker of microscopic, genetic and biochemical approaches, which has led to important advances in our understanding (Table 1). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Cells proliferate by division into similar daughter cells, a process that lies at the heart of cell biology. Extensive research on cell division has led to the identification of the many components and control elements of the molecular machinery underlying cellular division. Here we provide a brief review of prokaryotic and eukaryotic cell division and emphasize how new approaches such as systems and synthetic biology can provide valuable new insight.
    Systems and Synthetic Biology 09/2014; 8(3):173-8. DOI:10.1007/s11693-014-9132-z
  • Source
    • "Apart from the main function in the separation of oriC domains during chromosome segregation, ParA–ParB proteins participate in the control of replication initiation, cell division, growth and motility (Mierzejewska & Jagura- Burdzy, 2012). These additional roles are species-dependent and seem to depend on their ability to interact with other proteins (Bowman et al., 2008; Gruber & Errington, 2009; Ptacin et al., 2010; Ringgaard et al., 2011; Sullivan et al., 2009; Yamaichi et al., 2012). "
    [Show abstract] [Hide abstract]
    ABSTRACT: P. aeruginosa ParA belongs to a large subfamily of Walker-type ATPases acting as partitioning proteins in bacteria. ParA has the ability to both self-associate and interact with its partner ParB. Analysis of the deletion mutants defined the part of the protein involved in dimerization and interactions with ParB. Here, a set of the ParA alanine substitution mutants in the region between E67 and L85 was created and analyzed in vivo and in vitro. All mutants impaired in dimerization (substitutions at positions M74, H79, Y82, L84) were also defective in interactions with ParB suggesting that ParA-ParB interactions depend on the ability of ParA to dimerize. Mutants with alanine substitutions at positions E67, C68, L70, E72, F76, Q83 and L85 were not impaired in dimerization but defective in interactions with ParB. The dimerization interface partly overlaps the pseudo-hairpin, involved in interactions with ParB. ParA mutant derivatives tested in vitro showed no defects in ATPase activity. Two parA alleles, parA84, whose product can neither self-interact nor interact with ParB, and parA67, whose product is impaired in interactions with ParB but not in dimerization, were introduced into P. aeruginosa chromosome by homologous gene exchange. Both mutants showed defective separation of ParB foci but to different extents. Only PAO1161 parA84 was visibly impaired in chromosome segregation, growth rate and motilities similarly to a parAnull mutant.
    Microbiology 08/2014; 160(Pt 11). DOI:10.1099/mic.0.081216-0 · 2.84 Impact Factor
Show more