Molecular cloning of silkworm (Bombyx mori) antichymotrypsin

Abstract

The cDNA of silkworm (Bornbyx rnori) antichymotrypsin (sw-Achy) was cloned from larval fat body and its nucleotide sequence was determined. The deduced amino acid sequence of mature swAchy begins with Phel and ends with Phe384, with a preceding 16-amino-acid signal peptide. The amino-acid sequence similarities of sw-Achy with the serine-proteinase inhibitors (serpins) silkworm antitrypsin, tobacco hornworm alaserpin, human a-1-antitrypsin and human a-1 -antichymotrypsin were 29.6%, 30.3%, 26.1%, and 25.0%, respectively. The highly conserved amino acids in other serpins are also conserved in sw-Achy. sw-Achy is thought to be a new member of the serpin family. Multiple alignment of sw-Achy with 23 other kinds of serpin by the progressive method produced a phylogenetic tree in which all four insect serpins are grouped separately within one branch. The reactive site of sw-Achy with a-chymotrypsin was identified as Thr343-Ser344 by direct aminoacid sequence analysis of cleaved and purified protein.

Identification and characterization of a serine protease inhibitor (PtSerpin) in the swimming crab Portunus trituberculatus

“…PtSerpin shared high similarity with other two crustacean serpins, SpSerpin (S. paramamosain, ACY66635) [19] and PmSerpinB3 (P. monodon, ADC42877) [18,27]. Especially, the RCL showed the highly conserved in different species, which was in accordance with other reports [14,28].…”

A genome-wide analysis of genes and gene families involved in innate immunity of Bombyx mori

“…MsSerpin6 is involved in the PPO cascade by forming a complex with clipdomain serine proteases, MsPAP3 and MsHP8 (Zou and Jiang, 2005). BmSPN8 was reported as a chymotrypsin inhibitor named CI-8A (Narumi et al, 1993), but its function in immunity is not known.…”

Structure-Function Relationship of SW-AT-1, a Serpin-Type Protease Inhibitor in Silkworm

“…In this study, we analyzed the changes of SW-AT-1 structure under different temperatures and pH, although the stability and CD spectrum was roughly analyzed in previous reports [13], [14], [16], [17]. The contents of secondary elements fit quite well with the predicted 3D structure, which was mainly composed of alpha helices and a large protruding RCL (Figure 6).…”

“…The protein contains 384 Aa residues, with a preceding 16-amino-acid signal peptide. The reactive site of sw-Achy with α-chymotrypsin was identified as Thr343/Ser344 [13], [14]. In 1980’s, two serpins were identified in the hemolymph of B. mori .…”