An alternative cis-isoprenyltransferase activity in yeast that produces polyisoprenols with chain lengths similar to mammalian dolichols

Barbara Schenk, Jeffrey S. Rush, Charles J. Waechter, Markus Aebi

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

Dolichyl monophosphate (Dol-P) is a polyisoprenoid glycosyl carrier lipid essential for the assembly of a variety of glycoconjugates in the endoplasmic reticulum of eukaryotic cells. In yeast, dolichols with chain lengths of 14-17 isoprene units are predominant, whereas in mammalian cells they contain 19-22 isoprene units. In this biosynthetic pathway, t,t-farnesyl pyrophosphate is elongated to the appropriate long chain polyprenyl pyrophosphate by the sequential addition of cis-isoprene units donated by isopentenyl pyrophosphate with t,t,c-geranylgeranyl pyrophosphate being the initial intermediate formed. The condensation steps are catalyzed by cis-isoprenyltransferase (cis-IPTase). Genes encoding cis-IPTase activity have been identified in Micrococcus luteus, Escherichia coli, Arabidopsis thaliana, and Saccharomyces cerevisiae (RER2). Yeast cells deleted for the RER2 locus display a severe growth defect, but are still viable, possibly due to the activity of an homologous locus, SRT1. The dolichol and Dol-P content of exponentially growing revertants of RER2 deleted cells (Δrer2) and of cells overexpressing SRT1 have been determined by HPLC analysis. Dolichols and Dol-Ps with 19-22 isoprene units, unusually long for yeast, were found, and shown to be utilized for the biosynthesis of lipid intermediates involved in protein N-glycosylation. In addition, cis-IPTase activity in microsomes from Δrer2 cells overexpressing SRT1 was 7-to 17-fold higher than in microsomes from Δrer2 cells. These results establish that yeast contains at least two cis-IPTases, and indicate that the chain length of dolichols is determined primarily by the enzyme catalyzing the chain elongation stage of the biosynthetic process.

Original languageEnglish
Pages (from-to)89-98
Number of pages10
JournalGlycobiology
Volume11
Issue number1
DOIs
StatePublished - 2001

Keywords

  • Cis-isoprenyltransferase
  • Endoplasmic reticulum
  • Polyprenol biosynthesis
  • Protein N-glycosylation

ASJC Scopus subject areas

  • Biochemistry

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