The MBR1 gene from Saccharomyces cerevisiae is activated by and required for growth under sub-optimal conditions.
The MBR1 gene was isolated as a multicopy suppressor of the phenotype on glycerol medium of a Saccharomyces cerevisiae strain mutant for the Hap2/3/4/5 transactivator complex. In this paper, we show that Mbr1p is a limiting factor for growth on glycerol medium under the following sub-optimal culture conditions: in late growth phase, at low temperature, at high external pH or in the presence of 1,10-phenanthroline. Moreover, deletion of MBR1 protects cells against stress, whilst overexpression of this gene has the opposite effect. MBR1 expression is induced in the late growth phase and is negatively controlled by the cAMP-dependent protein kinase A (PKA). Both activation of PKA or overexpression of SOK1 or SCH9-two genes isolated as multicopy suppressors of a PKA null mutant-suppress the mbr1 growth defect. Our results indicate that Mbr1p is not an essential element of any one of these pathways. Deletion of SAC1, a gene implicated in vesicular transport, in association with MBR1 deletion, causes synthetic lethality. A possible role of Mbr1p in intracellular trafficking is discussed.
Reisdorf
P
P
Institut de Génétique et Microbiologie, URA CNRS D1354, Université Paris-Sud, Orsay, France.
Boy-Marcotte
E
E
Bolotin-Fukuhara
M
M
D001426:Bacterial Proteins / Q000502:physiology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics* / Q000502:physiology; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010641:Phenotype; D011494:Protein Kinases / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D015533:Transcriptional Activation
D001426:Bacterial Proteins; D005656:Fungal Proteins; C087579:MBR1 protein, S cerevisiae; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C099636:Sac1 protein, Chlamydomonas reinhardtii; D029701:Saccharomyces cerevisiae Proteins; D000242:Cyclic AMP; D011494:Protein Kinases; C071569:SCH9 protein kinase; D017868:Cyclic AMP-Dependent Protein Kinases