Heterologous expression implicates a GATA factor in regulation of nitrogen metabolic genes and ion homeostasis in the halotolerant yeast Debaryomyces hansenii.
The yeast Debaryomyces hansenii has a remarkable capacity to proliferate in salty and alkaline environments such as seawater. A screen for D. hansenii genes able to confer increased tolerance to high pH when overexpressed in Saccharomyces cerevisiae yielded a single gene, named here DhGZF3, encoding a putative negative GATA transcription factor related to S. cerevisiae Dal80 and Gzf3. Overexpression of this gene in wild-type S. cerevisiae increased caffeine and rapamycin tolerance, blocked growth in low glucose concentrations and nonfermentable carbon sources, and resulted in lithium- and sodium-sensitive cells. Sensitivity to salt could be attributed to a reduced cation efflux, most likely because of a decrease in expression of the ENA1 Na(+)-ATPase gene. Overexpression of DhGZF3 did not affect cell growth in a gat1 mutant but was lethal in the absence of Gln3. These are positive factors that oppose both Gzf3 and Dal80. Genome-wide transcriptional profiling of wild-type cells overexpressing DhGZF3 shows decreased expression of a number of genes that are usually induced in poor nitrogen sources. In addition, the entire pathway leading to Lys biosynthesis was repressed, probably as a result of a decrease in the expression of the specific Lys14 transcription factor. In conclusion, our results demonstrate that DhGzf3 can play a role as a negative GATA transcription factor when expressed in S. cerevisiae and that it most probably represents the only member of this family in D. hansenii. These findings also point to the GATA transcription factors as relevant elements for alkaline-pH tolerance.
García-Salcedo
Raúl
R
Departamento de Microbiología, Edificio Severo Ochoa, Campus de Rabanales, Universidad de Córdoba, Spain.
Casamayor
Antonio
A
Ruiz
Amparo
A
González
Asier
A
Prista
Catarina
C
Loureiro-Dias
Maria C
MC
Ramos
José
J
Ariño
Joaquín
J
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000468:Alkalies / Q000494:pharmacology; D027682:Cation Transport Proteins / Q000378:metabolism; D050980:GATA Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D007477:Ions; D009154:Mutation; D009584:Nitrogen / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D004718:Saccharomycetales / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D000254:Sodium-Potassium-Exchanging ATPase; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D015854:Up-Regulation
D000468:Alkalies; D027682:Cation Transport Proteins; C086375:ENA1 protein, S cerevisiae; C096100:GAT1 protein, S cerevisiae; D050980:GATA Transcription Factors; C071664:GLN3 protein, S cerevisiae; C106546:GZF3 protein, S cerevisiae; D007477:Ions; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D000251:Adenosine Triphosphatases; D000254:Sodium-Potassium-Exchanging ATPase; D009584:Nitrogen