RRC ID 3358
Author Daimon T, Katsuma S, Iwanaga M, Kang W, Shimada T.
Title The BmChi-h gene, a bacterial-type chitinase gene of Bombyx mori, encodes a functional exochitinase that plays a role in the chitin degradation during the molting process.
Journal Insect Biochem Mol Biol
Abstract The silkworm, Bombyx mori, has been recently demonstrated to contain a bacterial-type chitinase gene (BmChi-h) in addition to a well-characterized endochitinase gene (BmChitinase). The deduced amino acid sequence of BmChi-h showed extensive structural similarities with chitinases from bacteria such as Serratia marcescens chiA and baculoviruses (v-CHIA). Bacterial-type chitinase genes have not been found from any eukaryotes and viruses except for lepidopteran insects and lepidopteran baculoviruses. Thus, it was suggested that BmChi-h may be derived from a bacterial or baculovirus chitinase gene via horizontal gene transfer. In this report, we investigated the biological function of BmChi-h. Our enzymological study indicated that a chitinase encoded by BmChi-h has exo-type substrate preference, which is the same as S. marcescens chiA and v-CHIA, and different from BmChitinase, which has endo-type substrate preference. An immunohistochemical study revealed that BmChi-h localizes in the chitin-containing tissues during the molting stages, indicating that it plays a role in chitin degradation during molting. These results suggest that BmChi-h (exochitinase) and BmChitinase (endochitinase) may catalyze a native chitin by a concerted mechanism. Cloning and comparison of BmChi-h orthologues revealed that bacterial-type chitinase genes are highly conserved among lepidopteran insects, suggesting that the utilization of a bacterial-type chitinase during the molting process may be a general feature of lepidopteran insects.
Volume 35(10)
Pages 1112-23
Published 2005-10-1
DOI 10.1016/j.ibmb.2005.05.005
PII S0965-1748(05)00120-7
PMID 16102417
MeSH Amino Acid Sequence Amino Acid Substitution Animals Base Sequence Bombyx / enzymology Bombyx / genetics* Bombyx / growth & development Chitin / metabolism* Chitinases / genetics* Conserved Sequence DNA Primers Hydrogen-Ion Concentration Molecular Sequence Data Molting / physiology* Mutagenesis, Site-Directed Polymerase Chain Reaction Sequence Alignment Sequence Homology, Amino Acid
IF 3.827
Times Cited 41
Silkworms Samia cynthia ? Antheraea pernyi