Submitted to: American Society of Plant Physiologists Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 31, 1996
Publication Date: N/A
Technical Abstract: The bacterial Stress70 chaperone machine consists of three major components, the products of the dnaK, dnaJ and grpE genes. DnaK is a member of the 70 kDa superfamily of heat shock proteins. DnaK is the central molecular chaperone and consists of an N-terminal ATPase domain and a C-terminal peptide recognition domain. DnaJ proteins act to increase the rate of ATP hydrolysis by DnaK in a mechanism analogous to activation of low molecular weight GTPases by the GAP proteins. GrpE proteins further accelerate ATPase activity of DnaK by acting as nucleotide exchange factors. We have previously described plant homologues of DnaK and DnaJ. We now present evidence for an Arabidopsis homologue of GrpE. Although the protein encoded by atE1 is substantially smaller than GrpE (12,118 v. 21,798 kDa), there is approximately 30% homology (identity plus similarity) at the level of the deduced amino acid sequence. Furthermore, purified recombinant AtE1 stimulates the ATPase activity of DnaK/DnaJ to nearly the same extent as does GrpE. The only eukaryotic GrpE homologues identified to date are located within the yeast mitochondrial matrix. Analysis of the deduced amino acid sequence of AtE1 suggests that it is localized within the cytoplasm of plant cells.