Open AccessA degradation signal recognition in prokaryotes
Author(s) -
Park Eun Young,
Song Hyun Kyu
Publication year - 2008
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049507062826
Subject(s) - proteases , proteolysis , mutagenesis , biology , biophysics , biochemistry , signal transducing adaptor protein , chemistry , microbiology and biotechnology , mutant , enzyme , signal transduction , gene
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.