A respiratory-deficient mutation associated with high salt sensitivity in Kluyveromyces lactis.
A salt-sensitive mutant of Kluyveromyces lactis was isolated that was unable to grow in high-salt media. This mutant was also respiratory-deficient and temperature-sensitive for growth. The mutation mapped in a single nuclear gene that is the ortholog of BCS1 of Saccharomyces cerevisiae. The BCS1 product is a mitochondrial protein required for the assembly of respiratory complex III. The bcs1 mutation of S. cerevisiae leads to a loss of respiration, but, unlike in K. lactis, it is not accompanied by salt sensitivity. All the respiratory-deficient K. lactis mutants tested were found to be salt-sensitive compared to their isogenic wild-type strains. In the presence of the respiratory inhibitor antimycin A, the wild-type strain also became salt-sensitive. By contrast, none of the S. cerevisiae respiratory-deficient mutants tested showed increased salt sensitivity. The salt sensitivity of the Klbcs1 mutant, but not its respiratory deficiency, was suppressed by the multicopy KlVMA13 gene, a homolog of the S. cerevisiae VMA13 gene encoding a subunit of the vacuolar H(+)-ATPase. These results suggest that cellular salt homeostasis in K. lactis is strongly dependent on mitochondrial respiratory activity, and/or that the ion homeostasis of mitochondria themselves could be a primary target of salt stress.
Goffrini
Paola
P
Department of Genetics, Biology of Microorganisms, Anthropology, Evolution, University of Parma, Parco Area delle Scienze, Parma, Italy. paola.goffrini@unipr.it
D000074183:ATPases Associated with Diverse Cellular Activities; D014450:Electron Transport Complex III / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D005816:Genetic Complementation Test; D007716:Kluyveromyces / Q000187:drug effects* / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins; D008928:Mitochondria / Q000502:physiology; D024101:Mitochondrial Proteins / Q000235:genetics*; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009154:Mutation; D010101:Oxygen Consumption / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000494:pharmacology*; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
C472685:BCS1 protein, S cerevisiae; D005656:Fungal Proteins; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D029701:Saccharomyces cerevisiae Proteins; C447617:VMA13 protein, S cerevisiae; D012965:Sodium Chloride; D025262:Vacuolar Proton-Translocating ATPases; D000074183:ATPases Associated with Diverse Cellular Activities; D014450:Electron Transport Complex III