What question did this study set out to answer?

Determine whether threonine 204 serves as an obligatory intermediate phosphate acceptor during ATP hydrolysis in the chaperone protein Hsc70.

November 1, 1993Journal of Biological ChemistryOpen Access

Threonine 204 of the chaperone protein Hsc70 influences the structure of the active site, but is not essential for ATP hydrolysis.

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Authors

MOMelanie C. O’BrienThe University of Western Australia DMDavid McKayUniversity of Essex

Discussion

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Implication

Structural and kinetic analysis demonstrates that mutating threonine 204 alters the Hsc70 active site without stopping ATP hydrolysis, indicating it is not an essential catalytic intermediate.

Key Points

Determine whether threonine 204 serves as an obligatory intermediate phosphate acceptor during ATP hydrolysis in the chaperone protein Hsc70.
Constructed two site-directed point mutations at residue 204 (T204V and T204E) in the 44-kDa ATPase domain of Hsc70.
Assayed steady-state ATP hydrolysis kinetics to determine Km and kcat values for wild-type and mutant proteins.
Solved and refined the crystal structures of the T204V and T204E mutant proteins at 2.3-Å and 2.4-Å resolution, respectively.
Both T204V and T204E mutants displayed an increased Km for ATP of approximately 90 µM compared to approximately 1 µM in wild-type, along with elevated kcat values.
Crystal structures revealed that while the overall tertiary architecture remained largely unchanged, noticeable structural shifts occurred within the active site.
Both mutants maintained significant ATPase activity, demonstrating that threonine 204 is not an obligatory intermediate phosphate acceptor.

Cite This Study

O’Brien et al. (1993) studied this question.

synapsesocial.com/papers/6a8beb4ff07ad6ed43b23a9c https://doi.org/10.1016/s0021-9258(20)80529-8

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Implication

Structural and kinetic analysis demonstrates that mutating threonine 204 alters the Hsc70 active site without stopping ATP hydrolysis, indicating it is not an essential catalytic intermediate.

Threonine 204 of the chaperone protein Hsc70 influences the structure of the active site, but is not essential for ATP hydrolysis.

Discussion

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Implication

Key Points

Cite This Study

Threonine 204 of the chaperone protein Hsc70 influences the structure of the active site, but is not essential for ATP hydrolysis.

Discussion

Member takes

Implication

Key Points

Cite This Study

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