Isolation of a novel complex of the SWI/SNF family from Schizosaccharomyces pombe and its effects on in vitro transcription in nucleosome arrays.

The family of ATP-dependent chromatin-remodeling factors plays a central role in eukaryotic transcriptional regulation. These complexes can alter the structure of chromatin by mechanisms that involve nucleosome sliding, dissociation, or replacement over a specific promoter. The SWI/SNF chromatin-remodeling complex is required for transcriptional activation or repression in a subset of genes. In the present study we have isolated the spSWI/SNF complex from Schizosaccharomyces pombe, which has at least seven subunits among them spSwi1-like and the catalytic subunit spBrg1. These subunits are homologues to Swi1 and Swi2/Snf2, respectively in Sacharomyces cerevisiae. Moreover, we have demonstrated that spSWI/SNF is able to promote in vitro transcription by RNA polymerase II (RNAPII) in a reconstituted system. In our transcription assays with cellular extracts of Sc. pombe we did not observe inhibition when alpha-Swi1 antibodies were utilized, indicating that other chromatin-remodeling complexes may allow transcription in Sc. pombe.