Chromosomal addresses of the cohesin component Mcd1p.
We identified the chromosomal addresses of a cohesin subunit, Mcd1p, in vivo by chromatin immunoprecipitation coupled with high resolution PCR-based chromosomal walking. The mapping of new Mcd1p-binding sites (cohesin-associated regions [CARs]) in single-copy sequences of several chromosomes establish their spacing ( approximately 9 kb), their sequestration to intergenic regions, and their association with AT-rich sequences as general genomic properties of CARs. We show that cohesins are not excluded from telomere proximal regions, and the enrichment of cohesins at the centromere at mitosis reflects de novo loading. The average size of a CAR is 0.8-1.0 kb. They lie at the boundaries of transcriptionally silenced regions, suggesting they play a direct role in defining the silent chromatin domain. Finally, we identify CARs in tandem (rDNA) and interspersed repetitive DNA (Ty2 and subtelomeric repeats). Each 9-kb rDNA repeat has a single CAR proximal to the 5S gene. Thus, the periodicity of CARs in single-copy regions and the rDNA repeats is conserved. The presence and spacing of CARs in repetitive DNA has important implications for genomic stability and chromosome packaging/condensation.
Laloraya
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S
Howard Hughes Medical Institute, Carnegie Institution of Washington, Baltimore, Maryland 21210, USA. slaloraya@biochem.iisc.ernet.in
Guacci
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Koshland
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D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D002503:Centromere / Q000235:genetics; D002842:Chromatids / Q000502:physiology; D002868:Chromosomal Proteins, Non-Histone; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal / Q000235:genetics*; D004275:DNA, Ribosomal / Q000502:physiology; D005656:Fungal Proteins; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D020868:Gene Silencing / Q000502:physiology; D008938:Mitosis / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics*; D010750:Phosphoproteins; D011485:Protein Binding / Q000235:genetics; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015533:Transcriptional Activation / Q000502:physiology; D000097722:Cohesins
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004275:DNA, Ribosomal; D005656:Fungal Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; C490529:MCD1 protein, S cerevisiae