Catalyzes the terminal and only committed step in triacylglycerol synthesis by using diacylglycerol and fatty acyl CoA as substrates. Required for storage lipid synthesis. Upon expression in E.coli functions as a triacylglycerol synthase, making triacylglycerol (TG) from diolein and long-chain fatty acyl-CoA. Also functions as a wax synthase, incorporating palmityl alcohol into wax esters in the presence of palmitoyl-CoA. a 1,2-diacyl-sn-glycerol + an acyl-CoA = a triacyl-sn-glycerol + CoA a fatty acyl-CoA + a long chain fatty alcohol = a wax ester + CoA (9Z)-octadecenoyl-CoA + di-(9Z)-octadecenoylglycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + CoA hexadecan-1-ol + hexadecanoyl-CoA = CoA + hexadecanyl hexadecanoate Optimum pH is 6.5-7.2. Glycerolipid metabolism; triacylglycerol biosynthesis. A possible member of the dormancy regulon. Slightly induced in response to reduced oxygen tension (hypoxia) and by low levels of nitric oxide (NO). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. Belongs to the long-chain O-acyltransferase family.