Protein chaperones and non-protein substrates: on substrate promiscuity of GroEL

Abstract

Chaperonins are a group of molecular chaperones that form large multi subunit structures and are found in all forms of life. Encoded by the groEL and groES genes, bacterial chaperonins are required for appropriate folding of many cellular proteins. A significant number of bacterial species are known to express multiple copies of chaperonin genes, possibly to confer redundancy of GroEL function in these species. It is also likely that the paralogous GroELs might be undergoing diversification of function as a consequence of gene duplication. We argue in this article that different chaperonins in an organism might be involved in distinct biochemical functions that remain to be discovered, some of which might be modulated by different oligomeric states of the chaperonins.