The exclusive localization of the histone H3 variant CENP-A to centromeres

The exclusive localization of the histone H3 variant CENP-A to centromeres is essential for accurate chromosome segregation. CENP-ACse4. The down-regulated genes are enriched for CENP-ACse4 mislocalization to promoters, while the up-regulated genes correlate with those that are also transcriptionally up-regulated in an strain. Together, these data show that regulating centromeric nucleosome localization is not only critical for maintaining centromere function, but also for ensuring accurate promoter function and transcriptional regulation. Author Summary Chromosomes 53-03-2 IC50 carry the genetic material in cells. When cells divide, each child KLF1 cell must inherit a single copy of each chromosome. The centromere is the locus on each chromosome that ensures the equivalent distribution of chromosomes during cell division. One essential protein involved in this task is usually CENP-ACse4, which normally localizes exclusively to centromeres. Here, we investigated where CENP-ACse4 spreads in the genome when parts of its regulatory machinery are removed. We found that CENP-ACse4 becomes mislocalized to promoters, the region upstream of each gene that controls the activity of the gene. Consistent with this, the mislocalization of CENP-ACse4 to promoters leads to problems with gene activity. Our work shows that mislocalization of centromeric proteins can have effects beyond chromosome segregation defects, such as interfering with gene expression on chromosome arms. Introduction The eukaryotic genome 53-03-2 IC50 is usually packaged into chromatin, which consists of 147 bp repeating models of DNA wrapped around histone proteins to form nucleosomes [1]. Chromatin is important not only for packaging and protecting DNA, but also for regulating access of genes and other DNA elements to nuclear proteins involved in processes such as transcription, replication, and chromosome segregation. Most nucleosomes are composed of the canonical histone proteins, H2A, H2B, H3, and H4 [2]. However, the behavior and functions of nucleosomes can be altered both by chemically modifying canonical histones through post-translational modifications and by exchanging canonical histones for histone variants that alter nucleosome composition [2]. For example, H2A.Z is a variant of histone H2A and is found at promoter nucleosomes genome-wide where it regulates transcription [2C4]. In contrast, the conserved CENP-A variant (also called CenH3) replaces H3 in nucleosomes exclusively at the centromere where it regulates chromosome segregation [5C7]. Because changes in nucleosome composition can have a major impact on the underlying functions of the genome, it is critical to understand the mechanisms that control the localization of histone modifications and variants. The genomic incorporation of the budding yeast H2A.ZHtz1 (SGD ID: S000005372) histone variant is regulated by the SWR1 (SWR-C) and INO80 (INO80-C) chromatin remodeling complexes [8]. H2A.ZHtz1 localizes to intergenic regions, specifically near transcription start sites (TSS) at the +1 and -1 nucleosomes surrounding nucleosome-depleted regions (NDRs) [3, 4, 9C12]. In budding yeast, H2A.ZHtz1 nucleosomes are correlated with high 53-03-2 IC50 nucleosome turnover [13], which is proposed to assist transcriptional initiation or quick changes between transcriptional says [14C16]. SWR-C incorporates H2A.ZHtz1 into nucleosomes by exchanging H2A/H2B dimers for H2A.ZHtz1/H2B dimers [17C19]. In contrast, the mechanism of H2A.ZHtz1 removal from nucleosomes by INO80-C is less well understood because it has two reported activities that both lead to H2A.ZHtz1 exchange, either by swapping H2A.ZHtz1/H2B dimers for H2A/H2B dimers [20] or by promoting turnover of the entire nucleosome [8, 19]. The localization of the CENP-A variant is usually regulated by the histone chaperone HJURP (Scm3 in budding yeast), which is targeted specifically to centromeres [21C25]. Centromeric sequence and size are highly variable throughout eukaryotes and can be specified by either an underlying sequence or through epigenetic inheritance [26, 27]. Despite the diversity of centromeres, CENP-A is a conserved hallmark of all centromeres. The presence of CENP-A directs the formation of the kinetochore, a large protein complex that mediates attachments between.