Skip to main content
PMC home page
Biochemical Journal logoLink to Biochemical Journal
. 2003 Jul 1;373(Pt 1):191–200. doi: 10.1042/BJ20030144

Characterization of human phosphoserine aminotransferase involved in the phosphorylated pathway of L-serine biosynthesis.

Joo Youn Baek 1, Do Youn Jun 1, Dennis Taub 1, Young Ho Kim 1
PMCID: PMC1223456  PMID: 12633500

Abstract

In the present study, we first report two forms of human phosphoserine aminotransferase (PSAT) cDNA (HsPSAT alpha and HsPSAT beta). HsPSAT alpha has a predicted open reading frame comprising 324 amino acids, encoding a 35.2 kDa protein (PSAT alpha), whereas HsPSAT beta consists of an open reading frame comprising 370 amino acids that encodes a 40 kDa protein (PSAT beta). PSAT alpha is identical with PSAT beta, except that it lacks 46 amino acids between Val(290) and Ser(337) of PSAT beta, which is encoded by the entire exon 8 (138 bp). Both PSAT alpha and PSAT beta can functionally rescue the deletion mutation of the Saccharomyces cerevisiae counterpart. Reverse transcriptase-PCR analysis revealed that the expression of PSAT beta mRNA was more dominant when compared with PSAT alpha mRNA in all human cell lines tested. PSAT beta was easily detected in proportion to the level of mRNA; however, PSAT alpha was detected only in K562 and HepG2 cells as a very faint band. The relative enzyme activity of glutathione S-transferase (GST)-PSAT beta expressed in Escherichia coli appeared to be 6.8 times higher than that of GST-PSAT alpha. PSAT mRNA was expressed at high levels (approx. 2.2 kb) in the brain, liver, kidney and pancreas, and very weakly expressed in the thymus, prostate, testis and colon. In U937 cells, the levels of PSAT mRNA and protein appeared to be up-regulated to support proliferation. Accumulation of PSAT mRNA reached a maximum in the S-phase of Jurkat T-cells. These results demonstrate that although two isoforms of human PSAT can be produced by alternative splicing, PSAT beta rather than PSAT alpha is the physiologically functional enzyme required for the phosphorylated pathway, and indicate that the human PSAT gene is regulated depending on tissue specificity as well as cellular proliferation status with a maximum level expression in the S-phase.

Full Text

The Full Text of this article is available as a PDF (482.0 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Achouri Y., Rider M. H., Schaftingen E. V., Robbi M. Cloning, sequencing and expression of rat liver 3-phosphoglycerate dehydrogenase. Biochem J. 1997 Apr 15;323(Pt 2):365–370. doi: 10.1042/bj3230365. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Adams R. L., Lindsay J. G. Hydroxyurea reversal of inhibition and use as a cell-synchronizing agent. J Biol Chem. 1967 Mar 25;242(6):1314–1317. [PubMed] [Google Scholar]
  3. Belhumeur P., Fortin N., Clark M. W. A gene from Saccharomyces cerevisiae which codes for a protein with significant homology to the bacterial 3-phosphoserine aminotransferase. Yeast. 1994 Mar;10(3):385–389. doi: 10.1002/yea.320100311. [DOI] [PubMed] [Google Scholar]
  4. Boado R. J., Li J. Y., Nagaya M., Zhang C., Pardridge W. M. Selective expression of the large neutral amino acid transporter at the blood-brain barrier. Proc Natl Acad Sci U S A. 1999 Oct 12;96(21):12079–12084. doi: 10.1073/pnas.96.21.12079. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Cho H. M., Jun D. Y., Bae M. A., Ahn J. D., Kim Y. H. Nucleotide sequence and differential expression of the human 3-phosphoglycerate dehydrogenase gene. Gene. 2000 Mar 7;245(1):193–201. doi: 10.1016/s0378-1119(00)00009-3. [DOI] [PubMed] [Google Scholar]
  6. Collet J. F., Gerin I., Rider M. H., Veiga-da-Cunha M., Van Schaftingen E. Human L-3-phosphoserine phosphatase: sequence, expression and evidence for a phosphoenzyme intermediate. FEBS Lett. 1997 May 26;408(3):281–284. doi: 10.1016/s0014-5793(97)00438-9. [DOI] [PubMed] [Google Scholar]
  7. De Brabander M. J., Van de Veire R. M., Aerts F. E., Borgers M., Janssen P. A. The effects of methyl (5-(2-thienylcarbonyl)-1H-benzimidazol-2-yl) carbamate, (R 17934; NSC 238159), a new synthetic antitumoral drug interfering with microtubules, on mammalian cells cultured in vitro. Cancer Res. 1976 Mar;36(3):905–916. [PubMed] [Google Scholar]
  8. De Miranda J., Santoro A., Engelender S., Wolosker H. Human serine racemase: moleular cloning, genomic organization and functional analysis. Gene. 2000 Oct 3;256(1-2):183–188. doi: 10.1016/s0378-1119(00)00356-5. [DOI] [PubMed] [Google Scholar]
  9. Duncan K., Coggins J. R. The serC-aro A operon of Escherichia coli. A mixed function operon encoding enzymes from two different amino acid biosynthetic pathways. Biochem J. 1986 Feb 15;234(1):49–57. doi: 10.1042/bj2340049. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Feinberg A. P., Vogelstein B. "A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity". Addendum. Anal Biochem. 1984 Feb;137(1):266–267. doi: 10.1016/0003-2697(84)90381-6. [DOI] [PubMed] [Google Scholar]
  11. Furuya S., Tabata T., Mitoma J., Yamada K., Yamasaki M., Makino A., Yamamoto T., Watanabe M., Kano M., Hirabayashi Y. L-serine and glycine serve as major astroglia-derived trophic factors for cerebellar Purkinje neurons. Proc Natl Acad Sci U S A. 2000 Oct 10;97(21):11528–11533. doi: 10.1073/pnas.200364497. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Hass R., Giese G., Meyer G., Hartmann A., Dörk T., Köhler L., Resch K., Traub P., Goppelt-Strübe M. Differentiation and retrodifferentiation of U937 cells: reversible induction and suppression of intermediate filament protein synthesis. Eur J Cell Biol. 1990 Apr;51(2):265–271. [PubMed] [Google Scholar]
  13. Hester G., Stark W., Moser M., Kallen J., Marković-Housley Z., Jansonius J. N. Crystal structure of phosphoserine aminotransferase from Escherichia coli at 2.3 A resolution: comparison of the unligated enzyme and a complex with alpha-methyl-l-glutamate. J Mol Biol. 1999 Feb 26;286(3):829–850. doi: 10.1006/jmbi.1998.2506. [DOI] [PubMed] [Google Scholar]
  14. Ho C. L., Noji M., Saito M., Saito K. Regulation of serine biosynthesis in Arabidopsis. Crucial role of plastidic 3-phosphoglycerate dehydrogenase in non-photosynthetic tissues. J Biol Chem. 1999 Jan 1;274(1):397–402. doi: 10.1074/jbc.274.1.397. [DOI] [PubMed] [Google Scholar]
  15. Ho C. L., Noji M., Saito M., Yamazaki M., Saito K. Molecular characterization of plastidic phosphoserine aminotransferase in serine biosynthesis from Arabidopsis. Plant J. 1998 Nov;16(4):443–452. doi: 10.1046/j.1365-313x.1998.00313.x. [DOI] [PubMed] [Google Scholar]
  16. Jaeken J., Detheux M., Van Maldergem L., Foulon M., Carchon H., Van Schaftingen E. 3-Phosphoglycerate dehydrogenase deficiency: an inborn error of serine biosynthesis. Arch Dis Child. 1996 Jun;74(6):542–545. doi: 10.1136/adc.74.6.542. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Kim Y. H., Proust J. J., Buchholz M. J., Chrest F. J., Nordin A. A. Expression of the murine homologue of the cell cycle control protein p34cdc2 in T lymphocytes. J Immunol. 1992 Jul 1;149(1):17–23. [PubMed] [Google Scholar]
  18. Klomp L. W., de Koning T. J., Malingré H. E., van Beurden E. A., Brink M., Opdam F. L., Duran M., Jaeken J., Pineda M., Van Maldergem L. Molecular characterization of 3-phosphoglycerate dehydrogenase deficiency--a neurometabolic disorder associated with reduced L-serine biosynthesis. Am J Hum Genet. 2000 Oct 27;67(6):1389–1399. doi: 10.1086/316886. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Kozak M. Effects of long 5' leader sequences on initiation by eukaryotic ribosomes in vitro. Gene Expr. 1991 May;1(2):117–125. [PMC free article] [PubMed] [Google Scholar]
  20. Kunst F., Ogasawara N., Moszer I., Albertini A. M., Alloni G., Azevedo V., Bertero M. G., Bessières P., Bolotin A., Borchert S. The complete genome sequence of the gram-positive bacterium Bacillus subtilis. Nature. 1997 Nov 20;390(6657):249–256. doi: 10.1038/36786. [DOI] [PubMed] [Google Scholar]
  21. Metcalf W. W., Zhang J. K., Shi X., Wolfe R. S. Molecular, genetic, and biochemical characterization of the serC gene of Methanosarcina barkeri Fusaro. J Bacteriol. 1996 Oct;178(19):5797–5802. doi: 10.1128/jb.178.19.5797-5802.1996. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Misrahi M., Atger M., Milgrom E. A novel progesterone-induced messenger RNA in rabbit and human endometria. Cloning and sequence analysis of the complementary DNA. Biochemistry. 1987 Jun 30;26(13):3975–3982. doi: 10.1021/bi00387a035. [DOI] [PubMed] [Google Scholar]
  23. Sherr C. J. Cancer cell cycles. Science. 1996 Dec 6;274(5293):1672–1677. doi: 10.1126/science.274.5293.1672. [DOI] [PubMed] [Google Scholar]
  24. Smith Q. R., Momma S., Aoyagi M., Rapoport S. I. Kinetics of neutral amino acid transport across the blood-brain barrier. J Neurochem. 1987 Nov;49(5):1651–1658. doi: 10.1111/j.1471-4159.1987.tb01039.x. [DOI] [PubMed] [Google Scholar]
  25. Snell K. Enzymes of serine metabolism in normal, developing and neoplastic rat tissues. Adv Enzyme Regul. 1984;22:325–400. doi: 10.1016/0065-2571(84)90021-9. [DOI] [PubMed] [Google Scholar]
  26. Snell K., Natsumeda Y., Eble J. N., Glover J. L., Weber G. Enzymic imbalance in serine metabolism in human colon carcinoma and rat sarcoma. Br J Cancer. 1988 Jan;57(1):87–90. doi: 10.1038/bjc.1988.15. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Snell K., Weber G. Enzymic imbalance in serine metabolism in rat hepatomas. Biochem J. 1986 Jan 15;233(2):617–620. doi: 10.1042/bj2330617. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Wolosker H., Blackshaw S., Snyder S. H. Serine racemase: a glial enzyme synthesizing D-serine to regulate glutamate-N-methyl-D-aspartate neurotransmission. Proc Natl Acad Sci U S A. 1999 Nov 9;96(23):13409–13414. doi: 10.1073/pnas.96.23.13409. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Biochemical Journal are provided here courtesy of The Biochemical Society

RESOURCES