A Self-Associating Protein Critical for Chromosome Attachment, Division, and Polar Organization in Caulobacter

Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Cell (Impact Factor: 33.12). 10/2008; 134(6):956-68. DOI: 10.1016/j.cell.2008.07.016
Source: PubMed

ABSTRACT Cell polarization is an integral part of many unrelated bacterial processes. How intrinsic cell polarization is achieved is poorly understood. Here, we provide evidence that Caulobacter crescentus uses a multimeric pole-organizing factor (PopZ) that serves as a hub to concurrently achieve several polarizing functions. During chromosome segregation, polar PopZ captures the ParB*ori complex and thereby anchors sister chromosomes at opposite poles. This step is essential for stabilizing bipolar gradients of a cell division inhibitor and setting up division near midcell. PopZ also affects polar stalk morphogenesis and mediates the polar localization of the morphogenetic and cell cycle signaling proteins CckA and DivJ. Polar accumulation of PopZ, which is central to its polarizing activity, can be achieved independently of division and does not appear to be dictated by the pole curvature. Instead, evidence suggests that localization of PopZ largely relies on PopZ multimerization in chromosome-free regions, consistent with a self-organizing mechanism.

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Available from: Ariane Briegel, Jul 29, 2015
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    • "2B and C, 3A and B). This polar REZ is reminiscent of structures seen previously for an overexpression mutant of PopZ, a protein thought to anchor chromosomal origins to the pole, in Caulobacter crescentus (Ebersbach et al. 2008). "
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    • "s are separated presumably by ' bulk ' segregation mechanisms ( such as DNA replication , transcription , entropic unmixing , etc ) . This is followed by a fast , ParA - dependent phase , and completed by the anchoring of the partition complex at the new pole through a physical interaction between ParB and the PopZ matrix ( Bowman et al . , 2008 ; Ebersbach et al . , 2008 ; Shebelut et al . , 2010 ) ."
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    • "However, unlike DivIVA, these clusters do not appear to have an intrinsic affinity for curved membranes. Instead, they localize preferentially to subcellular regions devoid of chromosomal DNA, suggesting a role of the nucleoid in PopZ positioning [Ebersbach et al., 2008; Saberi and Emberly, 2010]. Recent work demonstrated that the characteristic cell cycle-dependent localizaton dynamics of PopZ are achieved by coupling the formation of new clusters to the segregation of the chromosomal origin regions [Laloux and Jacobs-Wagner, 2013]. "
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