Current Genetics

, Volume 30, Issue 5, pp 404–409

Cloning and characterization of the first two genes of the non-oxidative part of the Saccharomyces cerevisiae pentose-phosphate pathway

  • Thomas Miosga
  • F. K. Zimmermann
ORIGINAL PAPER
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Abstract

We have cloned and characterized the two remaining unknown genes of the non-oxidative part of the pentose-phosphate pathway of Saccharomyces cerevisiae encoding the enzymes D-ribulose-5-phosphate 3-epimerase (Rpe1p) and D-ribose-5-phosphate ketol-isomerase (Rki1p). Rpe1p has an unexpected high specific activity of 2148 mU × (mg protein)–1 in crude extracts. Deletion mutants of RPE1 show no enzyme activity and are unable to grow on D-xylulose. Unexpectedly, haploid rki1 deletion mutants are not viable. Functional expression of RKI1 was demonstrated following an increase of gene dosage in the haploid rki1 deletion mutant, which restored viability and specific D-ribose-5-phosphate ketol-isomerase activity. Both enzymes show high similarity to the deduced protein sequences of various open reading frames, expressed sequence tags or cDNAs from different organisms.

Key words D-ribulose-5-phosphate 3-epimerase D-ribose-5-phosphate ketol-isomerase Pentose-phosphate pathway Saccharomyces cerevisiae 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • Thomas Miosga
    • 1
  • F. K. Zimmermann
    • 1
  1. 1.Institut für Mikrobiologie und Genetik, Technische Hochschule Darmstadt, Schnittspahnstrasse 10, D-64287 Darmstadt, GermanyDE

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