Interaction of human recombinant alphaA- and alphaB-crystallins with early and late unfolding intermediates of citrate synthase on its thermal denaturation.
We have investigated the role of recombinant human alphaA- and alphaB-crystallins in the heat-induced inactivation and aggregation of citrate synthase. Homo-multimers of both alphaA- and alphaB-crystallins confer protection against heat-induced inactivation in a concentration-dependent manner and also prevent aggregation. Interaction of crystallins with early unfolding intermediates of citrate synthase reduces their partitioning into aggregation-prone intermediates. This appears to result in enhanced population of early unfolding intermediates that can be reactivated by its substrate, oxaloacetate. Both these homo-multimers do not form a stable complex with the early unfolding intermediates. However, they can form a soluble, stable complex with aggregation-prone late unfolding intermediates. This soluble complex formation prevents aggregation. Thus, it appears that the chaperone activity of alpha-crystallin involves both transient and stable interactions depending on the nature of intermediates on the unfolding pathway; one leads to reactivation of the enzyme activity while the other prevents aggregation.
Rajaraman
K
K
Centre for Cellular and Molecular Biology, 500 007, Hyderabad, India.
Raman
B
B
Ramakrishna
T
T
Rao
C M
CM
D002850:Chromatography, Gel; D002950:Citrate (si)-Synthase / Q000737:chemistry* / Q000378:metabolism; D003459:Crystallins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004795:Enzyme Stability / Q000187:drug effects / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D046911:Macromolecular Substances; D018832:Molecular Chaperones / Q000378:metabolism; D062907:Oxaloacetic Acid / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D011489:Protein Denaturation / Q000187:drug effects / Q000502:physiology; D017510:Protein Folding; D011994:Recombinant Proteins / Q000378:metabolism
D003459:Crystallins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D062907:Oxaloacetic Acid; D002950:Citrate (si)-Synthase