Volume 271, Number 46, Issue of November 15, 1996 pp. 29043-29048
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.

---

Reduction of CDP-diacylglycerol Synthase Activity Results in the Excretion of Inositol by Saccharomyces cerevisiae

(Received for publication, August 2, 1996, and in revised form, September 4, 1996)

From the Department of Biochemistry and Molecular Biology, University of Texas Medical School, Houston, Texas  77225

A yeast mutant, cdg1, was isolated on the basis of an inositol excretion phenotype. This mutant exhibited pleiotropic deficiencies in phospholipid biosynthesis, including reduced levels of CDP-diacylglycerol (DAG) synthase activity (Klig, L. S., Homann, M. J., Kohlwein, S. D., Kelley, M. J., Henry, S. A., and Carman, G. M. (1988) J. Bacteriol. 170, 1878-1886). In this study we present evidence that the molecular basis for the inositol excretion phenotype is a G³⁰⁵/A³⁰⁵ point mutation (Cys¹⁰²  Tyr substitution) within the CDS1 gene (encodes CDP-DAG synthase) of this mutant. Expression of CDP-DAG synthase activity from a plasmid-borne copy of the CDS1 gene in the cdg1 mutant was not down-regulated, and this expression also corrected the inositol excretion phenotype. Introduction of the above mutated gene (CDS1*) controlled by its endogenous promoter on a single copy plasmid into a cds1-null background reconstituted a transformant with the cdg1 phenotype, including reduced CDP-DAG synthase activity, elevated phosphatidylserine synthase activity, and inositol excretion into the growth medium. Expression of CDS1* in a single copy in the cdg1 mutant raised CDP-DAG synthase activity from 15 to 30% of derepressed wild-type yeast levels but still did not correct the inositol excretion phenotype. CDP-DAG synthase activity was not regulated in response to precursors of phospholipid biosynthesis in the cdg1 mutant either with or without a trans copy of the CDS1* gene. An open reading frame was identified 5 to the CDS1 locus, YBR0314, which also resulted in inositol excretion when present in trans in multiple copies.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				G. M. Carman and S. A. Henry Phosphatidic Acid Plays a Central Role in the Transcriptional Regulation of Glycerophospholipid Synthesis in Saccharomyces cerevisiae J. Biol. Chem., December 28, 2007; 282(52): 37293 - 37297. [Full Text] [PDF]

				L. C. Hancock, R. P. Behta, and J. M. Lopes Genomic Analysis of the Opi- Phenotype Genetics, June 1, 2006; 173(2): 621 - 634. [Abstract] [Full Text] [PDF]

				D. B. Ostrander, D. J. O'Brien, J. A. Gorman, and G. M. Carman Effect of CTP Synthetase Regulation by CTP on Phospholipid Synthesis in Saccharomyces cerevisiae J. Biol. Chem., July 24, 1998; 273(30): 18992 - 19001. [Abstract] [Full Text] [PDF]

				H. Shen and W. Dowhan Regulation of Phosphatidylglycerophosphate Synthase Levels in Saccharomyces cerevisiae J. Biol. Chem., May 8, 1998; 273(19): 11638 - 11642. [Abstract] [Full Text] [PDF]

				H. Shen and W. Dowhan Regulation of Phospholipid Biosynthetic Enzymes by the Level of CDP-Diacylglycerol Synthase Activity J. Biol. Chem., April 25, 1997; 272(17): 11215 - 11220. [Abstract] [Full Text] [PDF]