Isw1 chromatin remodeling ATPase coordinates transcription elongation and termination by RNA polymerase II

We demonstrate that distinct forms of the yeast chromatin-remodeling enzyme lsw1p sequentially regulate each stage of the transcription cycle. The lsw1a complex (lswlp/loc3p) represses gene expression at initiation through specific positioning of a promoter proximal dinucleosome, whereas the lsw1b complex (lswlp/loc2p/loc4p) acts within coding regions to control the amount of RNA polymerase (RNAPII) released into productive elongation and to coordinate elongation with termination and pre-mRNA processing. These effects of lsw1b are controlled via phosphorylation of the heptad repeat carboxy-terminal domain (CTD) of RNAPII and methylation of the chromatin template. The transcription elongation factor Spt4p antagonizes lsw1p and overcomes the lsw1p dependent pausing of RNAPII at the onset of the elongation cycle. Overall these studies establish the central role played by lsw1p in the coordination of transcription.