Cell cycle coordination and regulation of bacterial chromosome segregation dynamics by polarly localized proteins

Schofield, Whitman B.; Lim, Hoong Chuin; Jacobs‐Wagner, Christine

doi:10.1038/emboj.2010.207

Cited by 162 publications

(313 citation statements)

References 41 publications

(93 reference statements)

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“…When expressed in a wild-type Caulobacter background, ParA G16V-eYFP localized as foci at the cell poles (Fig. 1A) as described (6,20). In a ΔtipN background, ParA G16V -eYFP also efficiently formed foci at cell poles, whereas in the ΔpopZ background ParA G16V -eYFP was diffuse throughout the cell (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Caulobacter ParA accumulates at cell poles during and after chromosome segregation (6,20,21). To examine the roles of PopZ and TipN in the polar recruitment of ParA, we used a previously characterized monomeric variant of ParA (the dimerization-deficient ParA G16V ) that exhibits preferential localization at the cell pole rather than the nucleoid DNA in Caulobacter (6,20).…”

Section: Resultsmentioning

confidence: 99%

“…To examine the roles of PopZ and TipN in the polar recruitment of ParA, we used a previously characterized monomeric variant of ParA (the dimerization-deficient ParA G16V ) that exhibits preferential localization at the cell pole rather than the nucleoid DNA in Caulobacter (6,20). We created merodiploid strains that expressed ParA G16V -enhanced YFP (eYFP) in Caulobacter strains deficient in popZ or tipN.…”

Section: Resultsmentioning

confidence: 99%

“…In Caulobacter, two distinct polar protein factors affect ParA-mediated centromere segregation: the new polespecific protein TipN (16,17) and the polar organizing protein PopZ (18,19). TipN is a large, membrane-anchored, coiledcoil rich protein that localizes to the new pole throughout the cell cycle and, in addition to roles in localization of flagellar synthesis (16,17), affects processive parS segregation via an unknown mechanism (6,20).…”

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confidence: 99%

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Bacterial scaffold directs pole-specific centromere segregation

Ptacin¹,

Gahlmann

Bowman³

et al. 2014

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

156

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Bacteria use partitioning systems based on the ParA ATPase to actively mobilize and spatially organize molecular cargoes throughout the cytoplasm. The bacterium Caulobacter crescentus uses a ParA-based partitioning system to segregate newly replicated chromosomal centromeres to opposite cell poles. Here we demonstrate that the Caulobacter PopZ scaffold creates an organizing center at the cell pole that actively regulates polar centromere transport by the ParA partition system. As segregation proceeds, the ParB-bound centromere complex is moved by progressively disassembling ParA from a nucleoid-bound structure. Using superresolution microscopy, we show that released ParA is recruited directly to binding sites within a 3D ultrastructure composed of PopZ at the cell pole, whereas the ParB-centromere complex remains at the periphery of the PopZ structure. PopZ recruitment of ParA stimulates ParA to assemble on the nucleoid near the PopZ-proximal cell pole. We identify mutations in PopZ that allow scaffold assembly but specifically abrogate interactions with ParA and demonstrate that PopZ/ParA interactions are required for proper chromosome segregation in vivo. We propose that during segregation PopZ sequesters free ParA and induces target-proximal regeneration of ParA DNA binding activity to enforce processive and pole-directed centromere segregation, preventing segregation reversals. PopZ therefore functions as a polar hub complex at the cell pole to directly regulate the directionality and destination of transfer of the mitotic segregation machine.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Bacterial scaffold directs pole-specific centromere segregation

Ptacin¹,

Gahlmann

Bowman³

et al. 2014

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

156

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“…An example is the dynamic ParA-dependent segregation of the Caulobacter cresentus chromosome. In this case, ParA does not oscillate but instead uses filaments of ParA, which are guided to the poles by the action of TipN and PopZ (14,15). Thus, despite the clear similarity between ParA/B systems, evidence suggests there are a variety of different mechanisms used depending on the species and the cargo to be segregated.…”

mentioning

confidence: 99%

ParA-like protein uses nonspecific chromosomal DNA binding to partition protein complexes

Roberts

Wadhams

Hadfield

et al. 2012

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

125

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Recent data have shown that plasmid partitioning Par-like systems are used by some bacterial cells to control localization of protein complexes. Here we demonstrate that one of these homologs, PpfA, uses nonspecific chromosome binding to separate cytoplasmic clusters of chemotaxis proteins upon division. Using fluorescent microscopy and point mutations, we show dynamic chromosome binding and Walker-type ATPase activity are essential for cluster segregation. The N-terminal domain of a cytoplasmic chemoreceptor encoded next to ppfA is also required for segregation, probably functioning as a ParB analog to control PpfA ATPase activity. An orphan ParA involved in segregating protein clusters therefore uses a similar mechanism to plasmid-segregating ParA/B systems and requires a partner protein for function. Given the large number of genomes that encode orphan ParAs, this may be a common mechanism regulating segregation of proteins and protein complexes.

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