Journal of Lipid Research, Vol 35, 2254-2262, Copyright © 1994 by Lipid Research, Inc.
Regulation of phosphatidic acid biosynthetic enzymes in Saccharomyces cerevisiae
SA Minskoff, PV Racenis, J Granger, L Larkins, AK Hajra and ML Greenberg
Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor 48109.
Phosphatidic acid is the biosynthetic precursor of all glycerolipids. To
understand how phosphatidic acid biosynthesis is controlled in
Saccharomyces cerevisiae, we studied the regulation of three enzyme
activities involved in the synthesis of this glycerolipid precursor, i.e.,
glycerophosphate acyltransferase (GPAT), dihydroxyacetone phosphate
acyltransferase (DHAPAT), and acyl DHAP reductase. GPAT activity was
increased 3-fold, while DHAPAT activity was increased up to 9-fold in wild
type cells grown in a nonfermentable carbon source compared to that of
glucose-grown cells. The ratio of GPAT/DHAPAT activity was 12 in
glucose-grown cells but only 4 in cells grown in glycerol/ethanol. In the
previously characterized tpa1 mutant, (T. S. Tillman and R. M. Bell. 1986.
J. Biol. Chem. 261: 9144-9149), GPAT was decreased 2-fold and DHAPAT
27-fold compared to activities in the wild type. Acyl DHAP reductase
activity in both wild type and tpa1 cells grown on a nonfermentable carbon
source was increased approximately 2- fold over that of glucose-grown
cells. All three enzymatic activities increased as wild type cells grown on
glucose entered the stationary phase of growth. Therefore, GPAT, DHAPAT,
and acyl DHAP reductase activities appear to be regulated by the
respiratory state of the cell. None of the activities was affected to a
great extent by inositol, which is a key regulator of many enzymes involved
in the synthesis of PtdOH-derived phospholipids in S. cerevisiae, nor by
deletion of the mitochondrial genome.(ABSTRACT TRUNCATED AT 250 WORDS)
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