Over recent years the binding ability of the molecular chaperone cpn60 (GroEL14) and its co-chaperone cpn10 (GroES7) has been reported to occur under an assortment of specific conditions from the use of non-hydrolysable ATP analogues (namely adenosine 5′-[γ-thio]triphosphate) to requiring hydrolysable ATP for any interaction to occur. We have investigated this further using the molecular hydrodynamic methods (hydrodynamic bead modelling, sedimentation-velocity analytical ultracentrifugation and dynamic light-scattering), allowing the process to be followed under physiologically relevant dilute solution conditions, combined with absorption spectrophotometry to determine GroES7—GroEL14 interaction through the rate inhibition of the cpn60's ATPase activity by GroES7. The results found here indicate that the presence of hydrolysable ATP is required to facilitate correct GroES7 interaction with GroEL14 in solution.

Abbreviations used: cpn60, chaperone 60 (GroEL14); cpn10, cpn60's co-chaperone (GroES7); ATP[S], 5′-[γ-thio]triphosphate; PK, pyruvate kinase; PEP, phosphoenoylpyruvate; LDH, lactate dehydrogenase.

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Author notes

1

Present address and address to which correspondence should be sent: Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K. (e-mail c.walters@sheffield.ac.uk).