In Silico Modeling and Characterization of Squalene Synthase and Botryococcene Synthase Enzymes from a Green Photosynthetic Microalga Botryococcus braunii

Abstract

The green photosynthetic microalgae are considered as a major source of lipids from lacustrine and marine environments. Among them, Botryococcus braunii plays a key role due to its high efficiency production of huge amount of unsaturated hydrocarbons up to 75% of its dry weight. Evidently, more number of new compounds has been reported in sediments as deposits in both the marine and lacustrine environments. These depositions are reported as sediments from the algal lipids during the course of evolution. Botryococcene is one among the long chain hydrocarbon reported in higher amount extracellular as depositions from this microalga Botryococcus braunii race B. However, mass cultivation of this microalga for botryococcene as sustainable and renewable biofuel is a challenging target due to its doubling time and slow growth. Therefore, genetic engineering may play a key role to solve this issue. In addition to squalene synthase, squalene synthase-like genes have been reported from the race B of B. braunii which are SSL-1 (Presqualene diphosphate synthase), SSL-2 (Botryococcus squalene synthase) and SSL-3 (Botryococcene synthase) genes. This is an astounding report that these genes are controlling the production of long chain hydrocarbon botryococcene. Since, our present study clearly reveals that the squalene synthase and botryococcene synthase of B. braunii BB1 strain have very low protein homology of below 50% with human squalene synthase. Thus, it is clear that no high resolution studies have been conducted yet on these important enzymes. Even though, many overexpression studies have been carried out on these enzymes, x-ray diffraction studies may yield more information on the enzymes about its enzyme substrate specificity and it may help to improve the stability and efficiency of the enzymes for industrial aspects.