CDNA CLONING AND PATTERN OF EXPRESSION OF AN ADULT, FEMALE-SPECIFIC CHYMOTRYPSIN FROM AEDES-AEGYPTI MIDGUT

A cDNA for a midgut chymotrypsin, induced by a blood meal, has been cl oned and sequenced from the mosquito Aedes aegypti. The 938 base seque nce codes for a 268 amino acid protein, which contains an 18-residue s ignal peptide and a seven-residue activation peptide. The deduced amin o acid sequence contains several features typical of chymotrypsin prot eases, including the catalytic triad of serine proteases and the resid ues that determine the chymotrypsin substrate specificity pocket. The chymotrypsin mRNA, absent in larvae, pupae, males and newly emerged fe males, reaches detectable levels within 24 h post-emergence and attain s a maximum level 3-7 days after emergence. Translation of the chymotr ypsin mRNA is induced by feeding a protein meal, and there is a dramat ic increase in midgut chymotrypsin enzymatic activity after feeding. C hymotrypsin activity remained high during protein digestion, but chymo trypsin protein levels and enzymatic activity were almost undetectable once digestion was completed, 48 h after feeding. (C) 1997 Elsevier S cience Ltd.