Identification of active-site amino acid residues in the Chiba virus 3C-like protease.

ABSTRACT: The 3C-like protease of the Chiba virus, a Norwalk-like virus, is one of the chymotrypsin-like proteases. To identify active-site amino acid residues in this protease, 37 charged amino acid residues and a putative nucleophile, Cys139, within the GDCG sequence were individually replaced with Ala in the 3BC precursor, followed by expression in Escherichia coli, where the active 3C-like protease would cleave 3BC into 3B (VPg) and 3C (protease). Among 38 Ala mutants, 7 mutants (R8A, H30A, K88A, R89A, D138A, C139A, and H157A) completely or nearly completely lost the proteolytic activity. Cys139 was replaceable only with Ser, suggesting that an SH or OH group in the less bulky side chain was required for the side chain of the residue at position 139. His30, Arg89, and Asp138 could not be replace

SUBMITTER: Someya Y 

PROVIDER: S-EPMC136217 | biostudies-literature | 2002 Jun

REPOSITORIES: biostudies-literature