Identification and Analysis of GPAT Functional Genes of Corynebacterium glutamicum

Glycerol-3-phosphate acyltransferase (GPAT) is a key enzyme in the synthesis of triacylglycerols (TAGs). GPAT catalyzes the formation of lysophosphatidic acid (LPA) from glycerol-3-phosphate and fatty acyl-CoA, which is the initial reaction of the synthesis of TAG and glycerol-phospholipids. However, previous research showed that there was no definite gene ontology (GO) annotations of the GPAT gene in the complete genome sequence of Corynebacterium glutamicum ATCC13032. With the aid of bioinformatics and literature mining, several candidate genes encoding GPAT in Corynebacterium glutamicum ATCC13032 have been predicted. cg2777, a putative membrane protein gene, has been selected for the subsequent analysis and verification. The cg2777 gene has typical GPAT functional domain and four typical transmembrane helix regions. Compared with the GPAT gene sequences derived from a variety of oil-producing bacteria, there are several deletion and insertion regions in the amino acid sequence. By constructing the knockout and overexpression strain of the gene cg2777 , fermentation verification analysis implies that cg2777 performs partial GPAT function with low activity. As lipid synthesis is a complex bio-catalytic process involving multiple enzymes, the single overexpression of cg2777 gene cannot significantly increase the intracellular lipid content.