The nuclear Kluyveromyces lactis MRF1 gene encodes a mitochondrial class I peptide chain release factor that is important for cell viability.
We report the isolation and characterization of the Kluyveromyces lactis MRF1 gene encoding mitochondrial peptide chain release factor mRF-1. Over-expression of the KlMRF1 gene has a strong antisuppressive effect in a Saccharomyces cerevisiae mitochondrial nonsense suppressor strain. Inactivation of KlMRF1 results in a dual phenotype: most cells die after about 10-13 generations, while a small number of cells exceed this limit. We propose that the lethality is related to a loss of mitochondrial genome integrity. Surviving Klmrf1 cells are able to grow slowly on the non-fermentable substrate glycerol, indicating the existence of a second mitochondrial release factor activity. Our previous comparative analysis of class I release factors is refined by the incorporation of KlmRF-1 and ten recently identified prokaryotic release factor sequences.Keywords Kluyveromyces lactis middle dot Mitochondrial release factor middle dot MRF1 middle dot Peptide chain termination
Pel
H J
HJ
Laboratoire de Génétique Moléculaire, Université Paris-Sud, Bâtiment 400, F-91405 Orsay, France.
Rozenfeld
S
S
Bolotin-Fukuhara
M
M
D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000378:metabolism; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005798:Genes, Bacterial; D005800:Genes, Fungal; D007716:Kluyveromyces / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D010454:Peptide Termination Factors / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors
D005656:Fungal Proteins; C071720:MTF1 protein, S cerevisiae; D024101:Mitochondrial Proteins; D010454:Peptide Termination Factors; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors