title: Expression and evolution of the non-canonically translated yeast mitochondrial acetyl-CoA carboxylase Hfa1p.
abstract: The Saccharomyces cerevisiae genome encodes two sequence related acetyl-CoA carboxylases, the cytosolic Acc1p and the mitochondrial Hfa1p, required for respiratory function. Several aspects of expression of the HFA1 gene and its evolutionary origin have remained unclear. Here, we determined the HFA1 transcription initiation sites by 5' RACE analysis. Using a novel "Stop codon scanning" approach, we mapped the location of the HFA1 translation initiation site to an upstream AUU codon at position -372 relative to the annotated start codon. This upstream initiation leads to production of a mitochondrial targeting sequence preceding the ACC domains of the protein. In silico analyses of fungal ACC genes revealed conserved "cryptic" upstream mitochondrial targeting sequences in yeast species that have not undergone a whole genome duplication. Our Δhfa1 baker's yeast mutant phenotype rescue studies using the protoploid Kluyveromyces lactis ACC confirmed functionality of the cryptic upstream mitochondrial targeting signal. These results lend strong experimental support to the hypothesis that the mitochondrial and cytosolic acetyl-CoA carboxylases in S. cerevisiae have evolved from a single gene encoding both the mitochondrial and cytosolic isoforms. Leaning on a cursory survey of a group of genes of our interest, we propose that cryptic 5' upstream mitochondrial targeting sequences may be more abundant in eukaryotes than anticipated thus far.
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Fumi
authors.initials: F
authors.lastname: Suomi
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Katja E
authors.initials: KE
authors.lastname: Menger
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Geoffray
authors.initials: G
authors.lastname: Monteuuis
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Uta
authors.initials: U
authors.lastname: Naumann
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: V A Samuli
authors.initials: VA
authors.lastname: Kursu
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Antonina
authors.initials: A
authors.lastname: Shvetsova
authors.affiliation: Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Kastaniotis
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D000103:Acetyl-CoA Carboxylase / Q000096:biosynthesis* / Q000235:genetics*; D001483:Base Sequence; D018387:Codon, Initiator / Q000235:genetics; D019143:Evolution, Molecular; D015966:Gene Expression Regulation, Fungal; D007716:Kluyveromyces / Q000235:genetics; D008928:Mitochondria / Q000201:enzymology / Q000235:genetics*; D024101:Mitochondrial Proteins / Q000096:biosynthesis* / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010442:Peptide Chain Initiation, Translational; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D018387:Codon, Initiator; D024101:Mitochondrial Proteins; D029701:Saccharomyces cerevisiae Proteins; D000103:Acetyl-CoA Carboxylase; C085854:HFA1 protein, S cerevisiae