Molecular and General Genetics MGG

, Volume 238, Issue 3, pp 315–324

Isolation of the DLD gene of Saccharomyces cerevisiae encoding the mitochondrial enzyme D-lactate ferricytochrome c oxidoreductase

Authors

  • T. Lodi
    • Institute of GeneticsUniversity of Parma
  • I. Ferrero
    • Institute of GeneticsUniversity of Parma
Original Articles

DOI: 10.1007/BF00291989

Cite this article as:
Lodi, T. & Ferrero, I. Molec. Gen. Genet. (1993) 238: 315. doi:10.1007/BF00291989
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Abstract

In Saccharomyces cerevisiae the utilization of lactate occurs via specific oxidation of l- and d-lactate to pyruvate catalysed by l-lactate ferricytochrome c oxidoreductase (L-LCR) (EC 1.1.2.3) encoded by the CYB2 gene, and d-lactate ferricytochrome c oxidoreductase (D-LCR) (EC 1.1.2.4), respectively. We selected several lactate pyruvate+ mutants in a cyb2 genetic background. Two of them were devoid of D -LCR activity (dld mutants, belonging to the same complementation group). The mutation mapped in the structural gene. This was demonstrated by a gene dosage effect and by the thermosensitivity of the enzyme activity of thermosensitive revertants. The DLD gene was cloned by complementation for growth on d-, l-lactate in the strain WWF18-3D, carrying both a CYB2 disruption and the dld mutation. The minimal complete complementing sequence was localized by subcloning experiments. From the sequence analysis an open reading frame (ORF) was identified that could encode a polypeptide of 576 amino-acids, corresponding to a calculated molecular weight of 64000 Da. The deduced protein sequence showed significant homology with the previously described microsomal flavoprotein l-gulono-γ-lactone oxidase isolated from Rattus norvegicus, which catalyses the terminal step of l-ascorbic acid biosynthesis. These results are discussed together with the role of L-LCR and D-LCR in lactate metabolism of S. cerevisiae.

Key words

Saccharomyces cerevisiaeNuclear geneMitochondrial enzymeLactate dehydrogenaseFlavoprotein
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© Springer-Verlag 1993