Characterization of oligomeric rat liver mitochondrial glycerol-3-P acyltransferase

PELLON-MAISON, M.; PEREYRA, A.; COLEMAN, R.A.; GONZALEZ-BARO, M.R.

Iguazu, Misiones, Argentina

Congreso; XL Reunion anual de SAIB (Sociedad Argentina de Investigacion Bioquimica y Biologia Molecular); 2004

SAIB

Mitochondrial Glycerol-3- phosphate acyltransferase catalyzes the first and committed step in the de novo cellular glycerolipid synthesis, the formation of 1-acyl-sn-glycerol-3-phosphate (lysophosphatidic acid) from glycerol-3-phosphate and long chain fatty acyl-CoA substrates. To date, no studies have assessed the quaternary structure of the enzyme. It was therefore the aim of the present study to provide evidence for the existence of oligomeric mtGPAT complexes, using recombinant GPAT overexpressed in different eukaryotic systems. Using chemical crosslinking and SDS-PAGE dimeric, trimeric, tetrameric and a higher molecular mass complex were found. At inhibitory palmitoyl-CoA concentration the complex could also be observed. Using Triton X-100 combined with non-denaturing gel, mtGPAT was mainly found as a tetramer. mt GPATs trucated at the C-terminal domain were found to oligomerize normally. These results demonstrate that: 1) mtGPAT exists as oligomeric complexes. 2) high palmitoylCoA concentrations did not alter the oligomerization 3) The C-terminal domain of mtGPAT is not involved in the arrangement of the quaternary structure and 4) the possibility of mtGPAT interacting with other mitochondrial protein/s can not be overlooked.