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 chromatinremodeling 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 a-Swi1 antibodies were utilized, indicating that other chromatin-remodeling complexes may allow transcription in Sc. pombe.We thank Mrs. Cecilia Olivares for critical reading of the manuscript. This work was supported by Grant No. 1010824 from Fondecyt (Chile), Doctoral Fellowship No. 402084 from Conicyt (Chile) and Technology and Science Bicentennial Programme No. PSD-11 from World Bank-Conicyt (Chile)