INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Mitochondrial GPAT is essential for de novo triacylglycerol synthesis in crustacean hepatopancreas
Autor/es:
PELLON-MAISON, M.; GARCIA, C.F.; CATTANEO, E.R.; COLEMAN, R.A.; GONZALEZ-BARO, M.R.
Lugar:
Mar del Plata, Argentina
Reunión:
Congreso; XLIII Reunión Anual de la Sociedad Argentina de Investigación Bioquímica (SAIB); 2007
Institución organizadora:
Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular
Resumen:
In mammals, four isoforms of glycerol-3-phosphate acyltransferase (GPAT) have been described: Although ER-GPATs account for the highest specific activity in mammalian cells, it appears that mitochondrial GPAT1 may be the first-appearing acyltransferase in evolution. Bacterial GPAT has a molecular mass similar to GPAT1 and 30% aa identity.We report that triacylglycerol (TAG) synthesis in Macrobrachium borellii hepatopancreas depends solely on a mitochondrialGPAT. Hepatopancreas has a high-TAG biosynthetic activity. In mitochondria, we identified both GPAT activity and protein similar to mammalian GPAT1. The activity was resistant to inactivation by SH-reactive substances, it was activated by polymixin-B, and its substrate preference was for palmitoyl-CoA. We also visualized a 67-kDa protein band reactive to anti-rat liver GPAT1 antibody. Surprisingly, we did not detect GPAT activity in microsomes, even though they can synthesizeTAGfrom [ C]palmitate.When we used [ C]glycerol-3-phosphate as substrate, no [ C]TAG was produced in microsomes, and in mitochondria the mainly biosynthetic product was [ C]lysophosphatidate.We conclude that this crustacean model is unique in that the first step in the de novo biosynthetic pathwaysfor glycerolipids is carried out exclusively in mitochondria.