6vyi
From Proteopedia
Cryo-EM structure of human diacylglycerol O-acyltransferase 1
Structural highlights
Disease[DGAT1_HUMAN] Congenital chronic diarrhea with protein-losing enteropathy. The disease is caused by mutations affecting the gene represented in this entry. Function[DGAT1_HUMAN] Catalyzes the terminal and only committed step in triacylglycerol synthesis by using diacylglycerol and fatty acyl CoA as substrates. In contrast to DGAT2 it is not essential for survival. May be involved in VLDL (very low density lipoprotein) assembly. In liver, plays a role in esterifying exogenous fatty acids to glycerol. Functions as the major acyl-CoA retinol acyltransferase (ARAT) in the skin, where it acts to maintain retinoid homeostasis and prevent retinoid toxicity leading to skin and hair disorders.[1] [2] Publication Abstract from PubMedTriacylglycerols store metabolic energy in organisms and have industrial uses as foods and fuels. Excessive accumulation of triacylglycerols in humans causes obesity and is associated with metabolic diseases(1). Triacylglycerol synthesis is catalysed by acyl-CoA diacylglycerol acyltransferase (DGAT) enzymes(2-4), the structures and catalytic mechanisms of which remain unknown. Here we determined the structure of dimeric human DGAT1, a member of the membrane-bound O-acyltransferase (MBOAT) family, by cryo-electron microscopy at approximately 3.0 A resolution. DGAT1 forms a homodimer through N-terminal segments and a hydrophobic interface, with putative active sites within the membrane region. A structure obtained with oleoyl-CoA substrate resolved at approximately 3.2 A shows that the CoA moiety binds DGAT1 on the cytosolic side and the acyl group lies deep within a hydrophobic channel, positioning the acyl-CoA thioester bond near an invariant catalytic histidine residue. The reaction centre is located inside a large cavity, which opens laterally to the membrane bilayer, providing lipid access to the active site. A lipid-like density-possibly representing an acyl-acceptor molecule-is located within the reaction centre, orthogonal to acyl-CoA. Insights provided by the DGAT1 structures, together with mutagenesis and functional studies, provide the basis for a model of the catalysis of triacylglycerol synthesis by DGAT. Structure and catalytic mechanism of a human triacylglycerol-synthesis enzyme.,Sui X, Wang K, Gluchowski NL, Elliott SD, Liao M, Walther TC, Farese RV Jr Nature. 2020 May;581(7808):323-328. doi: 10.1038/s41586-020-2289-6. Epub 2020 May, 13. PMID:32433611[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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