title: Characterization of the N-terminal repeat domain of Escherichia coli ClpA-A class I Clp/HSP100 ATPase.
abstract: The ClpA, ClpB, and ClpC subfamilies of the Clp/HSP100 ATPases contain a conserved N-terminal region of approximately 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 approximately 40% alpha-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.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Lo
authors.forename: T A
authors.initials: TA
authors.lastname: Baker
authors.forename: R T
authors.initials: RT
authors.lastname: Sauer
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D055592:Biophysical Phenomena; D001703:Biophysics; D049071:Endopeptidase Clp; D004789:Enzyme Activation; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D006868:Hydrolysis; D016296:Mutagenesis / Q000235:genetics*; D017434:Protein Structure, Tertiary; D017384:Sequence Deletion / Q000235:genetics; D017385:Sequence Homology; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000378:metabolism*; D020079:Terminal Repeat Sequences
chemical_list: D029968:Escherichia coli Proteins; D012697:Serine Endopeptidases; C483568:ClpA protease, E coli; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases