Glycerol-3-phosphate acyltransferase in plants.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the transfer of an acyl group from an acyl donor to the sn-1 position of glycerol 3-phosphate. The plant cell contains three types of GPAT, which are located in the chloroplasts, mitochondria and cytoplasm, respectively. The enzyme in chloroplasts is soluble and uses acyl-(acyl-carrier protein) as the acyl donor, whereas the enzymes in the mitochondria and the cytoplasm are bound to membranes and use acyl-CoA as the acyl donor. cDNAs for GPAT of chloroplasts have been cloned from several plants, and the gene for the enzyme has been cloned from Arabidopsis thaliana. The amino acid sequences deduced from the nucleotide sequences of cDNAs indicate that the product of translation is a precursor of about 460 amino acid residues, which consists of a leader sequence of about 70 amino acid residues and a mature protein of about 400 residues, with a molecular mass of about 42 kDa. Genetic engineering of the unsaturation of fatty acids has been achieved by manipulation of the cDNA for the GPAT found in chloroplasts and has allowed modification of the ability of tobacco to tolerate chilling temperatures.