Coevolution of insect trypsins and inhibitors.
Many plant proteinase inhibitors have lysine at the P1 position, presumably to avoid hydrolysis by insect trypsins. Lepidopteran trypsins appear to have adapted to resist proteinase inhibitors through increased inhibitor hydrolysis and decreased binding to inhibitor hydrophilic reactive sites. Lepidopteran digestive trypsins prefer lysine at the P1 position and have substrate binding subsites more hydrophobic than trypsins from insects in other orders. All available sequences of sensitive and inhibitor-insensitive insect trypsins were aligned with porcine trypsin, for which interactions with Kunitz and Bowman-Birk inhibitor are known. After discounting conserved positions and positions not typical of sensitive or insensitive trypsins, the following residues were considered important to insect trypsin-PI interactions (chymotrypsin numbering): 60, 94, 97, 98, 99, 188, 190, 213, 215, 217, 219, 228. These residues support the Neighbor Joining analysis tree branches separating sensitive and insensitive trypsin sequences. Primary sequences interacting with PIs are around the active site, with some forming part of the S1 (188, 217, 219 and 228) or S4 (99, 215) pockets.
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, C.P. 26077, 05513-970, São Paulo, Brazil.
A R
AR
Lopes
M A
MA
Juliano
L
L
Juliano
W R
WR
Terra
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D019143:Evolution, Molecular; D019476:Insect Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D007313:Insecta / Q000201:enzymology* / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014357:Trypsin / Q000235:genetics* / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000235:genetics* / Q000378:metabolism
D000596:Amino Acids; D019476:Insect Proteins; D010940:Plant Proteins; D014361:Trypsin Inhibitors; D014357:Trypsin