Molecular cloning, developmental pattern and tissue expression of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase of the cockroach Blattella germanica

Abstract

In insects, 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (HMG‐CoA) synthesizes mevalonate for the production of nonsterol isoprenoids, which are essential for growth and differentiation. To understand the regulation and developmental role of HMG‐CoA reductase, we have cloned a full‐length HMG‐CoA reductase cDNA from the cockroach Blattella germanica. This cDNA clone was isolated using as a probe a partial cDNA of B. germanica HMG‐CoA reductase, amplified using the polymerase chain reaction. The composite 3433‐bp cDNA sequence contains an open reading frame encoding a polypeptide of 856 amino acids (Mr 93165). The C‐terminal region is more similar to hamster HMG‐CoA reductase than is the Drosophila melanogaster enzyme (79% and 69% conserved residues, respectively), and the potential transmembrane domains at the N‐terminal region are structurally conservative with both enzymes. The C‐terminal region of the B. germanica protein has been expressed as a fusion protein in Escherichia coli and exhibits HMG‐CoA reductase activity. Analysis of B. germanica HMG‐CoA reductase mRNA levels, reveals a 3.6‐kb transcript, that is overexpressed in 4‐day‐old embryos. Northern‐blot analysis of RNA samples from different adult female tissues shows high HMG‐CoA reductase mRNA levels in the ovary and lower levels in brain and muscle. Copyright © 1993, Wiley Blackwell. All rights reserved