The fission yeast GATA factor, Gaf1, modulates sexual development via direct down-regulation of ste11+ expression in response to nitrogen starvation.

ABSTRACT: Gaf1 is the first GATA family zinc-finger transcription factor identified in Schizosaccharomyces pombe. Here, we report that Gaf1 functions as a negatively acting transcription factor of ste11(+), delaying the entrance of cells exposed to transient nitrogen starvation into the meiotic cycle. gaf1? strains exhibited accelerated G(1)-arrest upon nitrogen starvation. Moreover, gaf1? mutation caused increased mating and sporulation frequency under both nitrogen-starved and unstarved conditions, while overexpression of gaf1(+) led to a significant impairment of sporulation. By microarray analysis, we found that approximately 63% (116 genes) of the 183 genes up-regulated in unstarved gaf1? cells were nitrogen starvation-responsive genes, and furthermore that 25 genes among the genes up-regulated by gaf1? mutation are Ste11 targets (e.g., gpa1(+), ste4(+), spk1(+), ste11(+), and mei2(+)). The phenotype caused by gaf1? mutation was masked by ste11? mutation, indicating that ste11(+) is epistatic to gaf1(+) with respect to sporulation efficiency, and accordingly that gaf1(+) functions upstream of ste11(+) in the signaling pathway governing sexual development. gaf1? strains showed accelerated ste11(+) expression under nitrogen starvation and increased ste11(+) expression even under normal conditions. Electrophoretic mobility shift assay analysis demonstrated that Gaf1 specifically binds to the canonical GATA motif (5'-HGATAR-3') spanning from -371 to -366 in ste11(+) promoter. Consequently, Gaf1 provides the prime example for negative regulation of ste11(+) transcription through direct binding to a cis-acting motif of its promoter.

SUBMITTER: Kim L 

PROVIDER: S-EPMC3416868 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature