REDESIGNING THE SUBSTRATE-SPECIFICITY OF THE HEPATITIS-C VIRUS NS3 PROTEASE

Background: Hepatitis C Virus (HCV) non-structural protein 3 (NS3) enc odes a trypsin-like serine protease that catalyzes the cleavages at th e NS3/NS4A, NS4A/NS4B, NS4B/NS5A and NS5A/NS5B junctions in the viral polyprotein and that shows a preference for a cysteine as the P1 resid ue, Results: We describe here a partial model of the HCV NS3 protease which allowed us to predict the position of the secondary structure el ements of the enzyme and of the residues involved in its specificity. By replacing these with the corresponding residues of Streptomyces gri seus protease B, we obtained a protease that, similar to the bacterial protein and unlike the wild-type enzyme, is able to cleave a substrat e containing a phenylalanine in the P1 position, Conclusions: These re sults confirm the reliability of our model and represent one of the fe w examples of redesign of a serine protease substrate specificity dire cted by molecular modelling. (C) Current Biology Ltd