RRC ID 11045
Author Urano K, Daimon T, Banno Y, Mita K, Terada T, Shimizu K, Katsuma S, Shimada T.
Title Molecular defect of isovaleryl-CoA dehydrogenase in the skunk mutant of silkworm, Bombyx mori.
Journal FEBS J
Abstract The isovaleric acid-emanating silkworm mutant skunk (sku) was first studied over 30 years ago because of its unusual odour and prepupal lethality. Here, we report the identification and characterization of the gene responsible for the sku mutant. Because of its specific features and symptoms similar to human isovaleryl-CoA dehydrogenase (IVD) deficiency, also known as isovaleric acidaemia, IVD dysfunction in silkworms was predicted to be responsible for the phenotype of the sku mutant. Linkage analysis revealed that the silkworm IVD gene (BmIVD) was closely linked to the odorous phenotype as expected, and a single amino acid substitution (G376V) was found in BmIVD of the sku mutant. To investigate the effect of the G376V substitution on BmIVD function, wild-type and sku-type recombinants were constructed with a baculovirus expression system and the subsequent enzyme activity of sku-type BmIVD was shown to be significantly reduced compared with that of wild-type BmIVD. Molecular modelling suggested that this reduction in the enzyme activity may be due to negative effects of G376V mutation on FAD-binding or on monomer-monomer interactions. These observations strongly suggest that BmIVD is responsible for the sku locus and that the molecular defect in BmIVD causes the characteristic smell and prepupal lethality of the sku mutant. To our knowledge, this is, aside from humans, the first characterization of IVD deficiency in metazoa. Considering that IVD acts in the third step of leucine degradation and the sku mutant accumulates branched-chain amino acids in haemolymph, this mutant may be useful in the investigation of unique branched-chain amino acid catabolism in insects.
Volume 277(21)
Pages 4452-63
Published 2010-11-1
DOI 10.1111/j.1742-4658.2010.07832.x
Description sku(臭蚕)の原因遺伝子はイソバレリル CoA脱水素酵素をコードするBmIVDである。a85系統(sku/sku)では、BmIVDのORF内に酵素活性を低下させる点突然変異が存在する。
PMID 21040472
MeSH Amino Acid Metabolism, Inborn Errors / genetics Amino Acid Sequence Amino Acid Substitution Animals Blotting, Northern Bombyx / enzymology Bombyx / genetics* Cloning, Molecular Enzyme Assays Gene Expression Profiling Hemiterpenes Humans Insect Proteins / genetics* Insect Proteins / metabolism Isovaleryl-CoA Dehydrogenase / deficiency Isovaleryl-CoA Dehydrogenase / genetics* Isovaleryl-CoA Dehydrogenase / metabolism Models, Molecular Molecular Sequence Data Mutant Proteins / metabolism Mutation* Odorants Pentanoic Acids / metabolism Phenotype Protein Conformation Reverse Transcriptase Polymerase Chain Reaction Sequence Analysis, DNA Sequence Homology, Amino Acid Substrate Specificity
IF 4.392
Times Cited 3
Silkworms a85