Control of phosphatidylserine biosynthesis through phosphatidylserine- mediated inhibition of phosphatidylserine synthase I in Chinese hamster ovary cells

O. Kuge, K. Hasegawa, K. Saito, M. Nishijima

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48 Citations (Scopus)

Abstract

Phosphatidylserine (PtdSer) synthesis in Chinese hamster ovary (CHO) cells occurs through the exchange of L-serine with the base moiety of phosphatidylcholine or phosphatidylethanolamine. The synthesis is depressed on the addition of PtdSer to the culture medium. A CHO cell mutant named mutant 29, whose PtdSer biosynthesis is highly resistant to this depression by exogenous PtdSer, has been isolated from CHO-K1 cells. In the present study, the PtdSer-resistant PtdSer biosynthesis in the mutant was traced to a point mutation in the PtdSer synthase I gene, pssA, resulting in the replacement of Arg-95 of the synthase by lysine. Introduction of the mutant pssA cDNA, but not the wild-type pssA cDNA, into CHO-K1 cells induced the PtdSer-resistant PtdSer biosynthesis. In a cell-free system, the serine base- exchange activity of the wild-type pssA-transfected cells was inhibited by PtdSer, but that of the mutant pssA-transfected cells was resistant to the inhibition. Like the mutant 29 cells, the mutant pssA-transfected cells grown without exogenous PtdSer exhibited an ≃2-fold increase in the cellular PtdSer level compared with that in CHO-K1 cells, although the wild-type pssA- transfected cells did not exhibit such a significant increase. These results indicated that the inhibition of PtdSer synthase I by PtdSer is essential for the maintenance of a normal PtdSer level in CHO-K1 cells and that Arg-95 of the synthase is a crucial residue for the inhibition.

Original languageEnglish
Pages (from-to)4199-4203
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number8
DOIs
Publication statusPublished - Apr 14 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Genetics
  • General

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