ROLE OF THE AMINO-TERMINAL DOMAIN IN GROES OLIGOMERIZATION

Digestions of the GroES oligomer with trypsin, chymotrypsin and Glu-C protease from Staphylococcus aureus V8 (V8) have helped to locate thre e regions in the GroES sequence that are sensitive to limited proteoly sis and have provided information of the GroES domains involved in mon omer-monomer and GroEL interaction. The removal of the first 20 or 27 amino acids of the N-terminal region of each GroES monomer by trypsin or chymotrypsin respectively, abolish the oligomerization of the GroES complex and its binding to GroEL. The V8-treatment of GroES promotes the breakage of the peptide bond between Glu(18) and Thr(19) but not t he liberation of the N-terminal fragment from the GroES oligomer, whic h is capable of forming with GroEL a complex active in protein folding . It is deduced from these results that the N-terminal region of the G roES monomer is involved in monomer-monomer interaction, providing exp erimental evidence that relates some biochemical properties of GroES w ith its three-dimensional structure at atomic resolution.