MUTATIONAL ANALYSIS OF THE PUTATIVE SUBSTRATE-BINDING SITE OF 3C PROTEINASE OF COXSACKIEVIRUS B3

Single amino acid substitutions were introduced into the putative subs trate-binding site of 3C proteinase (3C(pro)) of coxsackievirus B3, a member of the picornavirus family. Mutations at either Thr142, His161, Gly164, Gly169, or Ala172 severely impaired or abolished the proteoly tic activity except that a conservative Thr142 to Ser mutant had detec table activity. These results, which have shown the participation of t he 5 residues in 3C(pro) activity, are consistent with the earlier pre dictions that these residues might be involved in substrate binding.