3-HYDROXY-3-METHYLGLUTARYL-COENZYME-A SYNTHASE FROM BLATTELLA-GERMANICA - CLONING, EXPRESSION, DEVELOPMENTAL PATTERN AND TISSUE EXPRESSION

Insects do not synthezise cholesterol; the 3-hydroxy-3-methylglutaryl- coenzyme-A (HMG-CoA) produced by HMG-CoA synthase is transformed to me valonate by HMG-CoA reductase for the production of non-sterol isopren oids, which are essential for growth and differentiation. To understan d the regulation and developmental role of HMG-CoA synthase, we have c loned a 1658 bp cDNA that encompasses the entire transcription unit of the HMG-CoA synthase gene from the cockroach Blattella germanica. Thi s cDNA clone was isolated using as a probe a partial cDNA of B. german ica HMG-CoA synthase, amplified using the polymerase chain reaction. A nalysis of the nucleotide sequence reveals that the cDNA encodes a pol ypeptide of 453 amino acids (M(r) 50338) that is similar to vertebrate HMG-CoA synthase (74-76% conserved residues). The B. germanica cDNA h as been expressed as a fusion protein in Escherichia coli and exhibits HMG-CoA synthase activity. The HMG-CoA synthase transcript was differ entially expressed throughout B. germanica development. Analysis of RN A samples from different adult female tissues shows high HMG-CoA synth ase mRNA levels in the ovary and lower levels in brain and muscle.