Abstract
Cysteine 518 of the molecular chaperonin cpn60 (groEL) has been replaced with serine (C518S) by site-directed mutagenesis. The resulting mutant chaperonin protein is still functional and it can: (a) arrest the spontaneous folding of rhodanese in the absence of GroES and ATP, (b) assist refolding of the enzyme rhodanese in the presence of GroES and ATP/Mg2+, and (c) permit the urea-induced release and refolding of rhodanese from its complex with cpn60. ATP/Mg2+, alone, could discharge active rhodanese from cpn60 complexes formed with either wild type or C518S. In contrast with wild type cpn60, C518S has: (a) reduced stability of its quaternary structure, (b) reduced ability to reassemble tetradecamers after dissociation by urea; (c) reduced ATPase activity; and (d) more easily exposed hydrophobic surfaces. The data suggest that replacement of Cys-518 with Ser in cpn60 destabilizes its oligomeric structure, but there is no significant effect on cpn60 function or the stability of the monomers formed in urea.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call