1ats
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(New page: 200px<br /><applet load="1ats" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ats, resolution 2.43Å" /> '''THREONINE 204 OF THE...)
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Revision as of 09:00, 20 November 2007
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THREONINE 204 OF THE CHAPERONE PROTEIN HSC70 INFLUENCES THE STRUCTURE OF THE ACTIVE SITE BUT IS NOT ESSENTIAL FOR ATP HYDROLYSIS
Overview
The chaperone protein Hsc70 is an ATPase of unknown mechanism, although, the crystal structure of the 44-kDa ATPase domain has been solved. This, structure shows that the hydroxyl of threonine 204 is located close to the, gamma-phosphate of ATP, in a position where it might be an intermediate, phosphate acceptor in the hydrolysis reaction. We made two point mutations, at residue 204 of Hsc70, threonine to valine (T204V) and threonine to, glutamic acid (T204E). The wild-type ATPase domain had a Km for ATP of, approximately 1 microM; the mutants had Km values of approximately 90, microM. The kcat values for the mutant proteins were also increased. After, crystallization, the structures of the T204V and T204E proteins were, solved and refined with data to 2.3- and 2.4-A resolution, respectively., The overall tertiary structure of the mutants showed little change from, the wild type; however, significant changes were observed in the active, site. Analysis of the structures suggested possible reasons for the, changes in kinetic constants. Threonine 204 does not seem to be an, obligatory intermediate phosphate acceptor in the hydrolysis reaction, since the mutants retained appreciable ATPase activity.
About this Structure
1ATS is a Single protein structure of sequence from Bos taurus with MG and ADP as ligands. Active as Adenosinetriphosphatase, with EC number 3.6.1.3 Full crystallographic information is available from OCA.
Reference
Threonine 204 of the chaperone protein Hsc70 influences the structure of the active site, but is not essential for ATP hydrolysis., O'Brien MC, McKay DB, J Biol Chem. 1993 Nov 15;268(32):24323-9. PMID:8226982
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