Nucleotide sequence analysis of the nuclear gene coding for manganese superoxide dismutase of yeast mitochondria, a gene previously assumed to code for the Rieske iron‐sulphur protein

Abstract

We have previously reported the isolation of the gene coding for a 25‐kDa polypeptide present in a purified yeast QH2:cytochrome c oxidoreductase preparation, which was thus identified as the gene for the Rieske ironsulphur protein [Van Loon et al. (1983) Gene 26, 261–272]. Subsequent DNA sequence analysis reported here reveals, however, that the encoded protein is in fact manganese superoxide dismutase, a mitochondrial matrix protein. Comparison with the known amino acid sequence of the mature protein indicates that it is synthesized with an N‐terminal extension of 27 amino acids. In common with the N‐terminal extensions of other imported mitochondrial proteins, the presequence has several basic residues but lacks negatively charged residues. The function of these positive charges and other possible topogenic sequences are discussed. Sequences 5′ of the gene contain two elements that may be homologous to the suggested regulatory sites, UAS 1 and UAS 2 in the yeast CYC1‐gene [Guarente et al. (1984) Cell 36, 503–511]. The predicted secondary structures in manganese superoxide dismutase appear to be very similar to those reported for iron superoxide dismutase, suggesting similar three‐dimensional structures. Making use of the known three‐dimensional structure of the Fe enzyme, the Mn ligands are predicted.

Regulation of Cu,Zn‐ and Mn‐superoxide dismutase transcription in Saccharomyces cerevisiae

“…1). This is in agreement with the previously reported repression of SOD2 by glucose [3,68], and correlates with the glucose-induced 2-to 3-fold decrease in the amount of Cu,ZnSOD immunoreactive protein and activity [9]. In contrast, the amount of Cu,ZnSOD immunoreactive protein has been reported to be enhanced 50% under glucose-repressing conditions [6].…”

“…The activity or steady-state level of immunodetectable MnSOD is decreased under conditions of oxygen and heme deficiency and by glucose [.5,6]. The observations that glucose and anaerobiosis also diminish the steady-state level of mRNA indicate that these regulations operate at the transcriptional level [3,7,8]. Both the activity of Cu,ZnSOD and the amount of enzyme protein are depressed under anaerobic conditions and part of the enzyme is in the form of an apoprotein which can be reactivated by the addition of copper [9].…”

“…The SODZ-LacZ fusion was constructed by inserting upstream of the promoterless LacZ gene of YEp357 and YIp357 a polymerase chain reaction-amplified DNA fragment containing 410 nueleotides of the 5' non-coding region and 105 codons of the amin~te~inal coding sequence of SOL)1 [4]. The SOD2-LacZ fusion contained 558 nucleotides of the 5' non-coding region and 6 codons of the amino-terminal coding region of SOD2 [3] in YEp357R and YIp357R. The HEMl34acZ fusion was obtained by inserting 1076 nucleotides of the 5' non-coding region and 33 codons of the amino-terminal coding region of HEM13 (coproporphyrinogen oxidase 1141) in YEp357.…”

“…The yeast S. cerevisiae contains two superoxide dismutases. The manganese-superoxide dismutase (MnSOD) encoded by the gene SOD2 is located in the mitochondrial matrix [3], while the copper,zinc-superoxide dismutase (Cu,ZnSOD) encoded by the gene SODI is in the cytosol [4]. Several reports indicate that the two enzymes are regulated in yeast.…”

Biogenesis of Mitochondrial Energy Transducing Complexes

“…Furthermore, in many cases the content of serines and threonines is relatively high (Kaput et al, 1982;Viebrock et al, 1982;Maarse et al, 1984;Morohashi et al, 1984;Sadler et al, 1984;Sebald and Kruse, 1984;Suissa et al, 1984;Takiguchi et al, 1984;Wright et al, 1984;Gay and Walker, 1985;Guiard, 1985;Harnisch et al, 1985;Jaussi et al, 1985;Joh et al, 1985;Koerner et al, 1985;Marres et al, 1985;Mueckler and Pitot, 1985;Nyunoya et al, 1985;Takeda et al, 1985;Keng et al, 1986;Ohta and Kagawa, 1986). Subunit VI of the bc\ complex in yeast could be an exception, since it possesses a negatively charged amino-terminal sequence ; however, it is unknown where or whether at all it is proteolytically processed.…”