BLATTELLA-GERMANICA HAS 2 HMG-COA SYNTHASE GENES - BOTH ARE REGULATEDIN THE OVARY DURING THE GONADOTROPIC CYCLE

The isoprenoid pathway leads to various essential non-sterol products in insects. These end products have a crucial role in growth, differen tiation, sexual maturation, and reproduction. 3-Hydroxy-3-methylglutar yl coenzyme A (HMG-CoA) synthase (EC 4.1.3.5.) has generally been cons idered one of the committed steps of the pathway. We had previously re ported the cloning of a cytosolic HMG-CoA synthase cDNA in Blattella g ermanica; we have now isolated and characterized a new cDNA clone for HMG-CoA synthase in this insect. Analysis of this 1716 base pair cDNA reveals a deduced protein of 455 residues with a molecular mass of 51, 424 Da. The two HMG-CoA synthases have 69% identical amino acid residu es, and both lack an N-terminal leader peptide to target the protein i nto mitochondria. This HMG-CoA synthase cDNA can revert the Chinese ha mster ovary-K1-derived cell line, Mev-1, which is a defective mutant f or HMG-CoA synthase. Both HMG-CoA synthase genes are expressed differe ntly throughout development. Analysis of adult tissues shows higher ex pression in ovary and fat body. The expression of HMG-CoA synthase (EC 4.1.3.5.) and reductase (EC 1.1.1.34) genes during the gonadotrophic cycle in B. germanica shows that the three genes of the isoprenoid pat hway are developmentally regulated in the ovary.