Nucleotide sequence of the gene encoding the 11‐kDa subunit of the ubiquinol – cytochrome‐c oxidoreductase in Saccharomyces cerevisiae

Abstract

The nucleotide sequence of the gene encoding the 11-kDa subunit VIII of the ubiquinol-cytochrome-c oxidoreductase in Saccharomyces cerevisiae has been determined. The coding sequence has a length of 330 bp and is preceded at a distance of 361 bp by another reading frame, coding for a protein of as yet unknown function. The 11-kDa gene is transcribed independently of the URFx gene and transcription of both is sensitive to catabolite repression. Multiple 5'' and 3'' termini of transcripts of the gene for the 11-kDa subunit were identified by S1 nuclease protection analysis of DNA .cntdot. RNA hybrids. The 5'' termini map 52 .+-. 2 and 60 .+-. 2 nucleotides upstream of the initiation codon whereas the 3'' termini map 336 .+-. 2 and 350 .+-. 2 nucleotides downstream of the stop codon. The subunit VIII reading frame encodes a protein with a molecular mass of 12.4 kDa and a polarity of 37.6%. It is predicted to contain a high content of .beta.-sheet segments, which may be capable of forming a barrel-like structure in a lipid bilayer. A comparison of the sequence with those of the small subunits of the beef heart complex reveals similarity with the 9.5-kDa subunit VII (core-linked protein) characterized by Borchart et al. (1986) FEBS Lett. 200, 81-86. The significance of this is discussed.