Nucleosome remodeling and transcriptional repression are distinct functions of Isw1 in Saccharomyces cerevisiae.
The SANT domain is a nucleosome recognition module found in transcriptional regulatory proteins, including chromatin-modifying enzymes. It shows high functional degeneracy between species, varying in sequence and copy number. Here, we investigate functions in vivo associated with two SANT motifs, SANT and SLIDE, in the Saccharomyces cerevisiae Isw1 chromatin-remodeling ATPase. We show that differences in the primary structures of the SANT and SLIDE domains in yeast and Drosophila melanogaster reflect their different functions. In yeast, the SLIDE domain is required for histone interactions, while this is a function of the SANT domain in flies. In yeast, both motifs are required for optimal association with chromatin and for formation of the Isw1b complex (Isw1, Ioc2, and Ioc4). Moreover, nucleosome remodeling at the MET16 locus is defective in strains lacking the SANT or SLIDE domain. In contrast, the SANT domain is dispensable for the interaction between Isw1 and Ioc3 in the Isw1a complex. We show that, although defective in nucleosome remodeling, Isw1 lacking the SANT domain is able to repress transcription initiation at the MET16 promoter. Thus, chromatin remodeling and transcriptional repression are distinct activities of Isw1.
Pinskaya
Marina
M
Department of Biochemistry, University of Oxford, South Parks Road, Oxford, United Kingdom.
Nair
Anitha
A
Clynes
David
D
Morillon
Antonin
A
Mellor
Jane
J
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D042002:Chromatin Assembly and Disassembly; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000201:enzymology / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006657:Histones; C470547:IOC2 protein, S cerevisiae; C470549:IOC4 protein, S cerevisiae; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; C508234:MET16 protein, S cerevisiae; D010088:Oxidoreductases; D000251:Adenosine Triphosphatases; C470546:ISW1 protein, S cerevisiae