Genetic analysis of RSC58, which encodes a component of a yeast chromatin remodeling complex, and interacts with the transcription factor Swi6.

Before transcription can begin, the chromatin structure must be rearranged at the nucleosome level. In yeast the nucleosome remodeling complex RSC is involved in this process and it is essential for growth. Recent analysis of the RSC by mass spectrometry has suggested that the product of YLR033w, an essential gene of unknown function, is a novel component of the complex, and the gene has been renamed RSC58. Rsc58 is predicted to be 502 amino acids long. We have isolated five temperature-sensitive mutations in RSC58 and studied the cellular function of the gene. Our major findings are the following. (1) Two of the alleles have a frameshift mutation near the 3' end of the gene, in codons 482 and 485, respectively. The first mutation is associated with the more severe phenotype. This is compatible with the finding that removal of the C-terminal 25 residues of Rsc58 is lethal to cells. These results suggest that C-terminal region is essential for Rsc58 function. (2) RSC4, which codes for another member of the RSC, was found to be a multicopy suppressor of the phenotype of one of the temperature-sensitive mutants. (3) Two-hybrid analysis identified Swi6, a transcription factor, as a candidate interactor with Rsc58. An interaction between Rsc58 and Swi6 is also suggested by the fact that rsc58-ts Deltaswi6 double mutants show a more severe growth defect than either mutation alone. These results suggest the possibility that Rsc58 mediates between nucleosome remodeling and the initiation of transcription.