Namrata Misra, Prasanna Kumar Panda, Lala Bihari Sukla
Bioresources Engineering Department, Institute of Minerals and Materials Technology (formerly Regional Research lab), Council of Scientific and Industrial Research, Bhubaneswar-751 013, Orissa, India.
Glycerol-3 phosphate acyltransferase (GPAT) is an enzyme in the triacylglycerol (TAG) biosynthetic pathway that catalyses the conversion of glycerol-3 phosphate to lysophosphatidic acid. Targeting key enzymes involved in TAG pathway is considered to be a powerful strategy for augmented lipid accumulation in the organism. In the present study, the three-dimensional structure of the marine microalgae, Ostreococcus lucimarinus GPAT protein was developed based on the crystal structure of Cucurbita moschata GPAT protein as the template. The calculated Ramachandran plot using PROCHECK revealed that the modeled structure has 92.5%, 6.5%, 0.8% and 0.3% of residues in core, additional allowed, generously allowed regions and disallowed regions, respectively. Various other structure validation tools further confirmed the reliability and accuracy of the developed model. The predicted and validated model reveals the tertiary structure of GPAT monomer comprising of two domains, the smaller domain I which folds into a four helix bundle, and the larger domain II which is constructed from alternating α/β secondary structural elements that give rise to 9-stranded β sheet flanked by 11 α helices. Critical structural and sequence analysis of the developed model reveals the presence of H(X) 4 D motif; the latter being, a consensus sequence conserved amongst many glycerolipid acyltransferase. Computational analysis of the active site identification detected cluster of positively charged residues H 189 , K 243 , H 244 , R 285 and R 287 in the developed model which could be conjectured to be important in glycerol-3 phosphate recognition. The results of the present study may provide useful clues for experimental studies of strategic bioengineering of microalgae for enhanced biofuel production. Read More …