DNA helicase that possesses intrinsic ATP-dependent nucleosome-remodeling activity and is required for heterochromatin organization. Required for maintaining a heterochromatin chromatin structure at centromeres and subtelomeres by protecting these regions from euchromatin assembly. Enhances the nucleotide exchange activity of the pim1 guanine nucleotide exchange factor and abolishes histone-H3-mediated RanGAP inhibition. Involved in the construction of the centromeres. ATP + H2O = ADP + H(+) + phosphate interacts with the GDP-bound form of spi1. Belongs to the SNF2/RAD54 helicase family.