A Bombyx mori gene, BmChi-h, encodes a protein homologous to bacterial and baculovirus chitinases.
We have cloned and characterized a novel chitinase gene (BmChi-h) from the silkworm, Bombyx mori. BmChi-h cDNA has an open reading frame of 1,665 nucleotides, encoding a protein of 555 amino acid residues. The predicted protein shared extensive similarities with bacterial and baculovirus chitinases in both amino acid sequences (73% identity with Serratia marcescens chiA and 63% with Autographa californica nucleopolyhedrovirus chiA) and domain architectures. BmChi-h was a single-copy gene and located on chromosome 7. The expression of BmChi-h mRNA was observed in a stage- and tissue-specific manner that was almost identical to that of another chitinase gene previously cloned from B. mori. We further determined the overall genomic organization of BmChi-h. There was no intron in the ORF of BmChi-h. However, BmChi-h was transcribed from three promoters, which generated three isoforms in the 5'-UTR of the transcript. Phylogenetic analysis suggested that ancestral species of B. mori acquired the chitinase gene from a bacterium or an ancestral baculovirus via horizontal gene transfer.
Daimon
Takaaki
T
Laboratory of Insect Genetics and Bioscience, Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Hamada
Koutaro
K
Mita
Kazuei
K
Okano
Kazuhiro
K
Suzuki
Masataka G
MG
Kobayashi
Masahiko
M
Shimada
Toru
T
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D016367:Baculoviridae / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D005075:Biological Evolution; D015152:Blotting, Northern; D015139:Blotting, Southern; D012831:Bombyx / Q000235:genetics*; D002688:Chitinases / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D022761:Gene Transfer, Horizontal; D019476:Insect Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D018076:DNA, Complementary; D019476:Insect Proteins; D002688:Chitinases