Article

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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    • "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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    • "But other aggregating proteins, such as those that are misfolded have also shown such localization through the formation of inclusion bodies (Maisonneuve et al., 2008; de Groot et al., 2009; Winkler et al., 2010; Garcia-Fruitos et al., 2011). Recent theoretical (Saberi and Emberly, 2010, 2013; Winkler et al., 2010) and experimental (Bowman et al., 2008; Ebersbach et al., 2008; Winkler et al., 2010; Laloux and Jacobs-Wagner, 2013) work supports the hypothesis that the nucleoid can force aggregating structures within the cell to the poles. Additional levels of control, such as coupling to cell cycle associated spatial oscillations (Laloux and Jacobs-Wagner, 2013) or expression from genes that are spatially localized (Montero Llopis et al., 2010; Kuhlman and Cox, 2012) can further aid the nucleoid driven mechanism. "
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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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