Molecular cloning and characterization of the Saccharomyces cerevisiae CYT2 gene encoding cytochrome-c1– heme lyase

Authors

  • Alfred ZOLLNER,

    1. Institut für Genetik und Mikrobiologie der Universität München, Federal Republic of Germany
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  • Gerhard RÖDEL,

    1. Labor für Molekulare Biologie und Allgemeine Pathologie, Institut für Pathologie der Universität Ulm, Federal Republic of Germany
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  • Albert HAID

    Corresponding author
    1. Institut für Genetik und Mikrobiologie der Universität München, Federal Republic of Germany
      Correspondence to A. Haid, Institut für Genetik und Mikrobiologie der Universität München, Maria-Ward-Strasse 1a, W-8000 München, Federal Republic of Germany
      Fax: +49 89 178 5633.
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  • Note. The novel nucleotide sequence data published here have been submitted to the EMBL sequence data bank and are available under accession number X67017.

Correspondence to A. Haid, Institut für Genetik und Mikrobiologie der Universität München, Maria-Ward-Strasse 1a, W-8000 München, Federal Republic of Germany
Fax: +49 89 178 5633.

Abstract

Cytochrome c1, a subunit of the mitochondrial ubiquinol–cytochrome-c reductase, is synthesized on cytosolic ribosomes as a precusor protein of 37 kDa. Maturation to the mature 31-kDa form involves two proteolytic processing steps of the amino-terminal presequnce. After removal of the amino-terminal part by the matrix-localized processing peptidase, the carboxy-terminal part of the presequence is cleaved off by an unknown intermembrane space protease. This step depends on covalent linkage of heme to the apoprotein. At least two complementation groups (I and II) can be distinguished among mutants of the yeast Saccharomyces cerevisiae, which are defective in this second proteolytic processing, i.e. they accumulate the intermediate-sized form of cytochrome c1 instead of for cytochrome c1 [Sadler, I., Suda, K., Schatz, G., Kaudewitz, F. & Haid, A., (1984) EMBO J. 3, 2137–2143]. We report on the molecular cloning and characterization of the CYT2 gene representing complementation group I. It maps on chromosome XI and encodes a mitochondrial protein of about 26 kDa. Extensive similarity to Neurospora crassa and S. cerevisiae cytochrome-c–heme lyase, as well as the phenotype of cyt2 mutants, strogly suggest that we have identified the gene for cytochrome-c1–heme lyase.

Abbreviations
CCHL

cytochrome-c–heme lyase

CC1HL

cytochrome-c1–heme lyase

Enzyme
 

Ubiquinol–cytochrome-c reductase (EC 1.10.2.2)

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