Fission yeast SWI/SNF and RSC complexes show compositional and functional differences from budding yeast

Abstract

The Schizosaccharomyces pombe SWI/SNF family of ATP-dependent chromatin-remodeling complexes is now comprehensively analyzed, through composition, phenotypic and microarray analyses, thus broadly setting the stage for S. pombe as a new model organism for examining the SWI/SNF family remodelers. The S. pombe complexes are more akin to the metazoan SWI/SNF remodelers and have specific roles in repression of iron-transport genes. SWI/SNF chromatin-remodeling complexes have crucial roles in transcription and other chromatin-related processes. The analysis of the two members of this class in Saccharomyces cerevisiae, SWI/SNF and RSC, has heavily contributed to our understanding of these complexes. To understand the in vivo functions of SWI/SNF and RSC in an evolutionarily distant organism, we have characterized these complexes in Schizosaccharomyces pombe. Although core components are conserved between the two yeasts, the compositions of S. pombe SWI/SNF and RSC differ from their S. cerevisiae counterparts and in some ways are more similar to metazoan complexes. Furthermore, several of the conserved proteins, including actin-like proteins, are markedly different between the two yeasts with respect to their requirement for viability. Finally, phenotypic and microarray analyses identified widespread requirements for SWI/SNF and RSC on transcription including strong evidence that SWI/SNF directly represses iron-transport genes.