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Proc Natl Acad Sci U S A. 2015 Sep 29;112(39):12139-44. doi: 10.1073/pnas.1508749112. Epub 2015 Sep 14.

Regional centromeres in the yeast Candida lusitaniae lack pericentromeric heterochromatin.

Author information

1
Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260;
2
Department of Biochemistry, State University of New York at Buffalo, Buffalo, NY 14203;
3
Department of Biochemistry, Duke University, Durham, NC 27710.
4
Department of Biological Sciences, State University of New York at Buffalo, Buffalo, NY 14260; lrusche@buffalo.edu.

Abstract

Point centromeres are specified by a short consensus sequence that seeds kinetochore formation, whereas regional centromeres lack a conserved sequence and instead are epigenetically inherited. Regional centromeres are generally flanked by heterochromatin that ensures high levels of cohesin and promotes faithful chromosome segregation. However, it is not known whether regional centromeres require pericentromeric heterochromatin. In the yeast Candida lusitaniae, we identified a distinct type of regional centromere that lacks pericentromeric heterochromatin. Centromere locations were determined by ChIP-sequencing of two key centromere proteins, Cse4 and Mif2, and are consistent with bioinformatic predictions. The centromeric DNA sequence was unique for each chromosome and spanned 4-4.5 kbp, consistent with regional epigenetically inherited centromeres. However, unlike other regional centromeres, there was no evidence of pericentromeric heterochromatin in C. lusitaniae. In particular, flanking genes were expressed at a similar level to the rest of the genome, and a URA3 reporter inserted adjacent to a centromere was not repressed. In addition, regions flanking the centromeric core were not associated with hypoacetylated histones or a sirtuin deacetylase that generates heterochromatin in other yeast. Interestingly, the centromeric chromatin had a distinct pattern of histone modifications, being enriched for methylated H3K79 and H3R2 but lacking methylation of H3K4, which is found at other regional centromeres. Thus, not all regional centromeres require flanking heterochromatin.

KEYWORDS:

CSE4; Candida; Sir2; centromere; heterochromatin

PMID:
26371315
PMCID:
PMC4593121
DOI:
10.1073/pnas.1508749112
[Indexed for MEDLINE]
Free PMC Article

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