Molecular cloning and structural analysis of 3-hydroxy-3-methylglutaryl coenzyme A reductase of the moth Agrotis ipsilon

The enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, which plays a key role in isoprenoid biosynthesis, catalyses the synthesis of me valonate from HMG-CoA. Insects do not synthesize cholesterol de novo, rathe r mevalonate derivatives lead to non-sterol isoprenoids which are essential for development and reproduction. In this paper, we describe an HMG-CoA re ductase of the moth Agrotis ipsilon and we report its expression in fat bod y, ovary, muscle, brain and corpora allata tissues of adult specimens. The analysis of the cDNA reveals that it encodes a polypeptide of 833 amino aci ds (M-r = 89785). Alignments of this HMG-CoA reductase from A. ipsilon with the homologous sequences of other eukaryotes shows a high degree of conser vation in all species studied. Parsimony analysis based on these alignments produced dendrograms congruent with the current systematic schemes. This s uggests that, during eukaryote evolution, HMG-CoA reductase diversified in parallel with taxonomic splitting.