THE ISW1, CHD1 AND RSC REMODELERS COMBINE TO ORGANIZE CHROMATIN IN YEAST

JOSEFINA OCAMPO, SILVIA MORENO, SILVIA ROSSI; RAZVAN V CHEREJI; PETER R ERIKSSON; DAVID J CLARK

San Diego

Congreso; Experimental Biology, ASMBMB; 2016

ASMBMB

In yeast, most genes have a nucleosome-depleted region (NDR) at the promoter and an array of regularly spaced nucleosomes that is phased relative to the transcription start site (TSS). We addressed the roles of four remodeling machines (ISW1, ISW2, CHD1 and RSC) in specifying this chromatin organization. We sequenced nucleosomes from isogenic strains with the essential RSC8 gene linked to a GAL promoter and isw1 null, isw2 null or chd1 null mutations in all combinations. Globally, RSC depletion results in a shift of the array into the NDR, isw1 null shows reduced spacing and both isw1 null and chd1 null show weakened phasing, whereas isw2 null has no effect. Generally, chromatin organization in the multiple mutants is the sum of the effects observed in the single mutants, indicating that these remodelers are not redundant but have distinct functions. Our data suggest that RSC determines the location of the first (+1) nucleosome relative to the TSS, which is then used as a reference nucleosome by the spacing enzymes, ISW1 and CHD1, to build nucleosomal arrays on genes. Our current focus is on the interactions between RSC and the nucleosome spacing enzymes, and their roles in transcription.