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Characterization of the N‐terminal repeat domain of Escherichia coli ClpA—A class I Clp/HSP100 ATPase
Author(s) -
Lo John H.,
Baker Tania A.,
Sauer Robert T.
Publication year - 2001
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.41401
Subject(s) - escherichia coli , biology , aaa proteins , atpase , biochemistry , peptide sequence , enzyme , gene
The ClpA, ClpB, and ClpC subfamilies of the Clp/HSP100 ATPases contain a conserved N‐terminal region of ∼150 residues that consists of two approximate sequence repeats. This sequence from the Escherichia coli ClpA enzyme is shown to encode an independent structural domain (the R domain) that is monomeric and ∼40% α‐helical. A ClpA fragment lacking the R domain showed ATP‐dependent oligomerization, protein‐stimulated ATPase activity, and the ability to complex with the ClpP peptidase and mediate degradation of peptide and protein substrates, including casein and ssrA‐tagged proteins. Compared with the activities of the wild‐type ClpA, however, those of the ClpA fragment missing the R domain were reduced. These results indicate that the R domain is not required for the basic recognition, unfolding, and translocation functions that allow ClpA‐ClpP to degrade some protein substrates, but they suggest that it may play a role in modulating these activities.