The role of conserved residues of chagasin in the inhibition of cysteine peptidases.
We have evaluated the roles of key amino acids to the action of the natural inhibitor chagasin of papain-family cysteine peptidases. A W93A substitution decreased inhibitor affinity for human cathepsin L 100-fold, while substitutions of T31 resulted in 10-100-fold increases in the K(i) for cruzipain of Trypanosoma cruzi. A T31A/T32A double mutant had increased affinity for cathepsin L but not for cruzipain, while the T31-T32 deletion drastically affected inhibition of both human and parasite peptidases. These differential effects reflect the occurrence of direct interactions between chagasin and helix 8 of cathepsin L, interactions that do not occur with cruzipain.
dos Reis
Flavia C G
FC
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Bloco G, C.C.S., Cidade Universitária, Ilha do Fundão, Rio de Janeiro, 21949-900 RJ, Brazil.
Smith
Brian O
BO
Santos
Camila C
CC
Costa
Tatiana F R
TF
Scharfstein
Julio
J
Coombs
Graham H
GH
Mottram
Jeremy C
JC
Lima
Ana Paula C A
AP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017931:DNA Primers; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid; D014349:Trypanosoma cruzi / Q000201:enzymology
D015853:Cysteine Proteinase Inhibitors; D017931:DNA Primers; D015800:Protozoan Proteins; C435145:chagasin, Trypanosoma