A degradation signal recognition in prokaryotes.
The degradation of ssrA-tagged substrates in prokaryotes is conducted by a subset of ATP-dependent proteases, including ClpXP complex. More than 630 sequences of ssrA have been identified from 514 species, and are conserved in a wide range of prokaryotes. SspB protein markedly stimulates the degradation of these ssrA-tagged substrates by the ClpXP proteolytic machine. The dimeric SspB protein is composed of a compact ssrA-binding domain, which has a dimerization surface and a flexible C-terminal tail with a ClpX-binding motif at its very end. Since SspB is an adaptor protein for the ClpXP complex, designed mutagenesis, fluorescence spectroscopy, biochemistry and X-ray crystallography have been used to investigate the mechanism of delivery of ssrA-tagged proteins. In this paper the structural basis of ssrA-tag recognition by ClpX and SspB, as well as SspB-tail recognition by ZBD, is described.
Park
Eun Young
EY
School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
Song
Hyun Kyu
HK
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000737:chemistry*; D002352:Carrier Proteins / Q000737:chemistry*; D049071:Endopeptidase Clp / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006868:Hydrolysis; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry*; D012329:RNA, Bacterial / Q000737:chemistry*; D015398:Signal Transduction
D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D012329:RNA, Bacterial; C477700:sspB protein, E coli; C096222:tmRNA; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities