Molecular characterization of squalene synthase gene from plant

Abstract

Squalene synthase is a key enzyme of isoprenoid biosynthetic pathway, which is capable of diverting carbon flow specifically to the biosynthesis of sterol and hence, it is considered as a potential regulatory point for sterol metabolism. It is also a key regulatory enzyme in cholesterol biosynthesis pathway. Squalene synthase, one of the primary enzymes produced in plants which helps in the biosynthetic pathway of terpenoid and other steroid compounds. In addition to this, variants of squalene synthase gene appear to regulate plasma cholesterol levels in human population and therefore it can be linked to cardiovascular diseases. Squalene synthase inhibitors are effective in lowering plasma levels of total cholesterol. In Artemisia annua L. plants, the carbon needed for both sterol and artemisinin biosynthetic pathway is provided by mevalonate pathway in the form of farnesyl pyrophosphate (FPP). Hence, squalene synthase is a rate limiting enzyme of sterol biosynthetic pathway which compete with amospha-4,11-dienesynthase, which is the rate limiting enzyme of artemisinin biosynthetic pathway for the FPP. This competition will deplete the FPP pool towards artemisinin biosynthesis. So, squalene synthase, is an important target for the down regulation of sterols.