Demonstration by genetic suppression of interaction of GroE products with many proteins

Abstract

The way in which proteins attain and maintain their final form is of fundamental importance. Recent work has focused on the role of a set of ubiquitous proteins, termed chaperonins, in the assembly of phage and multisubunit proteins. The range of chaperonin action is unknown; they could interact with most cellular polypeptides or have a limited subset of protein partners. Included in the chaperonin family is the essential heat-shock regulated Escherichia coli groEL gene product. Over-expression of the groE operon in E. coli causes enhanced assembly of heterologously expressed ribulose bisphosphate carboxylase subunits and suppresses the heat-sensitive mutant phenotype of several dnaA alleles. It has been inferred that suppression of heat-sensitive mutations is confined to dnaA alleles and that this confinement could reflect an interaction between the groE operon products and a dnaA protein aggregate at the replication origin. We now report that multiple copies of the groE operon suppress mutations in genes encoding several diverse proteins. Our data indicate a general role for the groE operon products, the GroEL and GroES proteins, in the folding-assembly pathways of many proteins.

Molecular and genetic analyses of the Caenorhabditis elegans dpy-2 and dpy-10 collagen genes: a variety of molecular alterations affect organismal morphology.

“…This model is consistent with observations that mutant actin in Drosophila can induce the heat shock response (Parker- Thornberg and Bonner, 1987) and that in E. coli the GroEL heat shock protein can suppress a number of temperature-sensitive mutations in unrelated genes (Van Dyk et al, 1989). If this model is correct, suppression may not be occurring through direct physical interactions but rather may represent a general physiological response to the mutant proteins.…”

Co-overexpression of bacterial GroESL chaperonins partly overcomes non-productive folding and tetramer assembly of E. coli-expressed human medium-chain acyl-CoA dehydrogenase (MCAD) carrying the prevalent disease-causing K304E mutation

“…Pointmutations which "alter the folding pathway without influencing the properties of the native form" have been identified and carefully characterized for the tailspike protein of bacteriophage P22 and suppres sor pointmutations in the same protein could be se lected which overcome the defect [27]. It has also been shown, that GroESL co-overproduction can suppress point mutations in several diverse bacterial genes [28].…”

GroEL‐Mediated protein folding

“…Here, little difference in apparent binding constants was observed for the series A, P, L, K, D, all substituted for a particular glycine in CS. More generally, point mutations in many proteins appear to be able to elicit more efficient binding, relative to the wild-type protein, by GroEL (for example, Van Dyk et al, 1989;Gordon et al, 1994). The breadth of these effects and the lack of recognizable specificity in the affected residues argues more for an effect on the overall pathway or kinetics of folding, rather than for alteration of specific binding sites for GroEL.…”