Review: Allostery in chaperonins

Chaperonins mediate protein folding in an ATP-dependent manner. ATP binding and hydrolysis by chaperonins are subject to both homotropic and heterotro pic allosteric regulation. In the case of GroEL and CCT, homotropic regulat ion by ATP is manifested in nested cooperativity, which involves positive i ntra-ring cooperativity and negative interring cooperativity in ATP binding . Both types of cooperativity are modulated by various heterotropic alloste ric effectors, which include nonfolded proteins, ADP, Mg2+, monovalent ions such as K+, and cochaperonins in the case of type I chaperonins such as Gr oEL. Here, the allosteric properties of chaperonins are reviewed and new re sults of ours are presented with regard to allosteric effects of ADP. The r ole of allostery in the reaction cycle and folding function of chaperonins is discussed. (C) 2001 Academic Press.