ClpS modulates but is not essential for bacterial N-end rule degradation.
In eubacteria, the ClpS adaptor has been proposed to be essential for degradation of N-end rule substrates by the AAA(+) protease ClpAP. To test this model, we assayed degradation of substrates bearing N-end rule sequences isolated in a genetic screen for efficient degradation tags. ClpS was not vital for degradation in vivo but rather stimulated turnover in a sequence-specific manner. Although ClpS substantially enhanced degradation of N-end substrates at low substrate concentrations in vitro, it suppressed the degradation rate when substrate was saturating. Thus, we conclude that ClpAP recognizes N-end rule substrates directly, whereas ClpS modulates this degradation pathway.
Wang
Kevin H
KH
Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Sauer
Robert T
RT
Baker
Tania A
TA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D049071:Endopeptidase Clp / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002352:Carrier Proteins; C454820:ClpS protein, E coli; D029968:Escherichia coli Proteins; C483568:ClpA protease, E coli; D049071:Endopeptidase Clp