Mutation in the Pro-Peptide Region of a Cysteine Protease Leads to Altered Activity and Specificity—A Structural and Biochemical Approach
Fig 6
Structural comparison of catalytic cleft structures of I86F and I86L with that of the WT (TS).
The catalytic domains are in surface presentation; I86L, coloured in green; I86F, coloured in light blue; WT (TS) in light orange. The pro-peptide parts blocking the catalytic clefts are presented as stick model with Carbon atoms coloured as their respective catalytic domain surface colour. a) and b) Superposition of I86L and I86F mutants with the WT (TS) respectively. c) Individual I86L, I86F and WT (TS) in a similar orientation of a) and b). The arrow indicates a cavity formed by two residues Tyr168 and Tyr174. d) Superposition of I86L, I86F and WT (TS) showing some residues of the catalytic cleft responsible for micro-changes in the cleft conformation of the mutants. The catalytic dyad residues are C132A and H266. The Cɑ trace is drawn on WT (TS)structure with mature domain in light orange and pro-peptide in magenta. The position of pro-peptide also represents the flow of substrate during Michaelis comlex formation.The co-ordinates and structure factors of the WT (TS) have been taken from pdb_id 3TNX. ‘m’ and ‘p’ tags in the sequence number represent mature and pro-peptide region respectively.