Abstract:
:Regulated proteolysis is required to execute many cellular programs. In Caulobacter crescentus, timely degradation of the master regulator CtrA by ClpXP protease is essential for cell-cycle progression and requires the colocalization of CtrA and RcdA. Here, we establish a biochemical framework to understand regulated proteolysis in C. crescentus and show that RcdA is not an adaptor for CtrA degradation. CtrA is rapidly degraded without RcdA and is recognized with an affinity comparable with the best ClpXP substrates. In contrast, SspBalpha, the alpha-proteobacterial homolog of SspB, functions as an adaptor to enhance degradation of specific substrates. Cargo-free SspBalpha is also itself a substrate of ClpXP-mediated proteolysis. Thus, our analysis (i) reveals the consequences of both direct and adaptor-stimulated recognition in mediating substrate specificity in vitro, (ii) reveals a potential regulatory role of controlled adaptor stability, and (iii) suggests that cell-cycle regulation of CtrA stability depends on repression of its intrinsic degradation rather than adaptor-mediated enhancement.
journal_name
Proc Natl Acad Sci U S Aauthors
Chien P,Perchuk BS,Laub MT,Sauer RT,Baker TAdoi
10.1073/pnas.0701776104subject
Has Abstractpub_date
2007-04-17 00:00:00pages
6590-5issue
16eissn
0027-8424issn
1091-6490pii
0701776104journal_volume
104pub_type
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