HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 278, Issue 23, 20785-20794, June 6, 2003

This Article Full Text Full Text (PDF) All Versions of this Article: 278/23/20785    most recent M301394200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Park, T.-S. Articles by Carman, G. M. Search for Related Content PubMed PubMed Citation Articles by Park, T.-S. Articles by Carman, G. M. Social Bookmarking                      What's this?

Phosphorylation of CTP Synthetase on Ser³⁶, Ser³³⁰, Ser³⁵⁴, and Ser⁴⁵⁴ Regulates the Levels of CTP and Phosphatidylcholine Synthesis in Saccharomyces cerevisiae^*

Tae-Sik Park, Daniel J. O'Brien and George M. Carman 

From the Department of Food Science, Cook College, New Jersey Agricultural Experiment Station, Rutgers University, New Brunswick, New Jersey 08901

The Saccharomyces cerevisiae URA7-encoded CTP synthetase is phosphorylated and stimulated by protein kinase C. We examined the hypothesis that Ser³⁶, Ser³³⁰, Ser³⁵⁴, and Ser⁴⁵⁴, contained in a protein kinase C sequence motif in CTP synthetase, were target sites for the kinase. Synthetic peptides containing a phosphorylation motif at these serine residues served as substrates for protein kinase C in vitro. Ser Ala (S36A, S330A, S354A, and S454A) mutations in CTP synthetase were constructed by site-directed mutagenesis and expressed normally in a ura7 ura8 double mutant that lacks CTP synthetase activity. The CTP synthetase activity in extracts from cells bearing the S36A, S354A, and S454A mutant enzymes was reduced when compared with cells bearing the wild type enzyme. Kinetic analysis of purified mutant enzymes showed that the S36A and S354A mutations caused a decrease in the V_max of the reaction. This regulation could be attributed in part by the effects phosphorylation has on the nucleotide-dependent oligomerization of CTP synthetase. In contrast, CTP synthetase activity in cells bearing the S330A mutant enzyme was elevated, and kinetic analysis of purified enzyme showed that the S330A mutation caused an elevation in the V_max of the reaction. In vitro data indicated that phosphorylation of CTP synthetase at Ser³³⁰ affected the phosphorylation of the enzyme at another site. The phosphorylation of CTP synthetase at Ser³⁶, Ser³³⁰, Ser³⁵⁴, and Ser⁴⁵⁴ residues was physiologically relevant. Cells bearing the S36A, S354A, and S454A mutations had reduced CTP levels, whereas cells with the S330A mutation had elevated CTP levels. The alterations in CTP levels correlated with the regulatory effects CTP has on the pathways responsible for the synthesis of the membrane phospholipid phosphatidylcholine.

Received for publication, February 10, 2003 , and in revised form, March 31, 2003.

^* This work was supported in part by United States Public Health Service, National Institutes of Health Grant GM-50679. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

To whom correspondence should be addressed: Dept. of Food Science, Rutgers University, 65 Dudley Rd., New Brunswick, NJ 08901. Tel.: 732-932-9611 (ext. 217); Fax: 732-932-6776; E-mail: carman{at}aesop.rutgers.edu.

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

This article has been cited by other articles:

				F. A. Lunn, J. E. MacDonnell, and S. L. Bearne Structural Requirements for the Activation of Escherichia coli CTP Synthase by the Allosteric Effector GTP Are Stringent, but Requirements for Inhibition Are Lax J. Biol. Chem., January 25, 2008; 283(4): 2010 - 2020. [Abstract] [Full Text] [PDF]

				M. J. Higgins, P. R. Graves, and L. M. Graves Regulation of Human Cytidine Triphosphate Synthetase 1 by Glycogen Synthase Kinase 3 J. Biol. Chem., October 5, 2007; 282(40): 29493 - 29503. [Abstract] [Full Text] [PDF]

				Y.-F. Chang, S. S. Martin, E. P. Baldwin, and G. M. Carman Phosphorylation of Human CTP Synthetase 1 by Protein Kinase C: IDENTIFICATION OF Ser462 AND Thr455 AS MAJOR SITES OF PHOSPHORYLATION J. Biol. Chem., June 15, 2007; 282(24): 17613 - 17622. [Abstract] [Full Text] [PDF]

				M.-G. Choi and G. M. Carman Phosphorylation of Human CTP Synthetase 1 by Protein Kinase A: IDENTIFICATION OF Thr455 AS A MAJOR SITE OF PHOSPHORYLATION J. Biol. Chem., February 23, 2007; 282(8): 5367 - 5377. [Abstract] [Full Text] [PDF]

				D. R. Evans and H. I. Guy Mammalian Pyrimidine Biosynthesis: Fresh Insights into an Ancient Pathway J. Biol. Chem., August 6, 2004; 279(32): 33035 - 33038. [Full Text] [PDF]

				W. M. Iwanyshyn, G.-S. Han, and G. M. Carman Regulation of Phospholipid Synthesis in Saccharomyces cerevisiae by Zinc J. Biol. Chem., May 21, 2004; 279(21): 21976 - 21983. [Abstract] [Full Text] [PDF]

				M.-G. Choi, T.-S. Park, and G. M. Carman Phosphorylation of Saccharomyces cerevisiae CTP Synthetase at Ser424 by Protein Kinases A and C Regulates Phosphatidylcholine Synthesis by the CDP-choline Pathway J. Biol. Chem., June 20, 2003; 278(26): 23610 - 23616. [Abstract] [Full Text] [PDF]