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Title: SpbR overproduction reveals the importance of proteolytic degradation for cell pole development and chromosome segregation in Caulobacter crescentus
Summary

In most rod‐shaped bacteria, DNA replication is quickly followed by chromosome segregation, when one of the newly duplicated centromeres moves across the cell to the opposite (or ‘new’) pole. Two proteins inCaulobacter crescentus, PopZ and TipN, provide directional cues at the new pole that guide the translocating chromosome to its destination. We show that centromere translocation can be inhibited by an evolutionarily conserved pole‐localized protein that we have named SpbR. When overproduced, SpbR exhibits aberrant accumulation at the old pole, where it physically interacts with PopZ. This prevents the relocation of PopZ to the new pole, thereby eliminating a positional cue for centromere translocation. Consistent with this, the centromere translocation phenotype of SpbR overproducing cells is strongly enhanced in a ∆tipNmutant background. We find that pole‐localized SpbR is normally cleared by ClpXP‐mediated proteolysis before the time of chromosome segregation, indicating that SpbR turnover is part of the cell cycle‐dependent program of polar development. This work demonstrates the importance of proteolysis as a housekeeping activity that removes outgoing factors from the developing cell pole, and provides an example of a substrate that can inhibit polar functions if it is insufficiently cleared.

 
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NSF-PAR ID:
10459518
Author(s) / Creator(s):
 ;  
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Molecular Microbiology
Volume:
111
Issue:
6
ISSN:
0950-382X
Page Range / eLocation ID:
p. 1700-1714
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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