Prion-dependent switching between respiratory competence and deficiency in the yeast nam9-1 mutant.
Nam9p is a protein of the mitochondrial ribosome. The respiration-deficient Saccharomyces cerevisiae strain MB43-nam9-1 expresses Nam9-1p containing the point mutation S82L. Respiratory deficiency correlates with a decrease in the steady level of some mitochondrially encoded proteins and the complete lack of mitochondrially encoded cytochrome oxidase subunit 2 (Cox2). De novo synthesis of Cox2 in MB43-nam9-1 is unaffected, indicating that newly synthesized Cox2 is rapidly degraded. Respiratory deficiency of MB43-nam9-1 is overcome by transient overexpression of HSP104, by deletion of HSP104, by transient exposure to guanidine hydrochloride, and by expression of the C-terminal portion of Sup35, indicating an involvement of the yeast prion [PSI(+)]. Respiratory deficiency of MB43-nam9-1 can be reinduced by transfer of cytosol from S. cerevisiae that harbors [PSI(+)]. We conclude that nam9-1 causes respiratory deficiency only in combination with the cytosolic prion [PSI(+)], presenting the first example of a synthetic effect between cytosolic [PSI(+)] and a mutant mitochondrial protein.
Chacinska
A
A
Institute of Biochemistry and Biophysics, 02-106 Warsaw, Poland.
Boguta
M
M
Krzewska
J
J
Rospert
S
S
D003600:Cytosol / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D019791:Guanidine / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D008928:Mitochondria / Q000502:physiology; D009687:Nuclear Proteins; D010101:Oxygen Consumption / Q000187:drug effects; D010454:Peptide Termination Factors; D010641:Phenotype; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017354:Point Mutation; D011328:Prions / Q000235:genetics / Q000502:physiology*; D014176:Protein Biosynthesis; D012097:Repressor Proteins; D012269:Ribosomal Proteins / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D004271:DNA, Fungal; D004272:DNA, Mitochondrial; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; C072080:NAM9 protein, S cerevisiae; D009687:Nuclear Proteins; D010454:Peptide Termination Factors; D010940:Plant Proteins; D011328:Prions; D012097:Repressor Proteins; D012269:Ribosomal Proteins; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C111957:cox2 protein, Glycine soja; C070972:HsP104 protein, S cerevisiae; D003576:Electron Transport Complex IV; D019791:Guanidine