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Title: Rad51-Rad52 Mediated Maintenance of Centromeric Chromatin in Candida albicans
Authors: Mitra, Sreyoshi
Gomez-Raja, Jonathan
Larriba, German
Dubey, Dharani Dhar
Sanyal, Kaustuv
Keywords: Genetics & Heredity
Stalled Replication Forks
Neighbor-Joining Method
Mating-Type Locus
Histone Cenp-A
Microtubule Interaction
Gene Conversion
Budding Yeast
Issue Date: 2014
Publisher: Public Library of Science
Citation: Mitra, S; Gomez-Raja, J; Larriba, G; Dubey, DD; Sanyal, K, Rad51-Rad52 Mediated Maintenance of Centromeric Chromatin in Candida albicans. PLoS Genetics 2014, 10 (4), e1004344
PLoS Genetics
Abstract: Specification of the centromere location in most eukaryotes is not solely dependent on the DNA sequence. However, the non-genetic determinants of centromere identity are not clearly defined. While multiple mechanisms, individually or in concert, may specify centromeres epigenetically, most studies in this area are focused on a universal factor, a centromere-specific histone H3 variant CENP-A, often considered as the epigenetic determinant of centromere identity. In spite of variable timing of its loading at centromeres across species, a replication coupled early S phase deposition of CENP-A is found in most yeast centromeres. Centromeres are the earliest replicating chromosomal regions in a pathogenic budding yeast Candida albicans. Using a 2-dimensional agarose gel electrophoresis assay, we identify replication origins (ORI7-LI and ORI7-RI) proximal to an early replicating centromere (CEN7) in C. albicans. We show that the replication forks stall at CEN7 in a kinetochore dependent manner and fork stalling is reduced in the absence of the homologous recombination (HR) proteins Rad51 and Rad52. Deletion of ORI7-RI causes a significant reduction in the stalled fork signal and an increased loss rate of the altered chromosome 7. The HR proteins, Rad51 and Rad52, have been shown to play a role in fork restart. Confocal microscopy shows declustered kinetochores in rad51 and rad52 mutants, which are evidence of kinetochore disintegrity. CENP-A(CACSe4) levels at centromeres, as determined by chromatin immunoprecipitation (ChIP) experiments, are reduced in absence of Rad51/Rad52 resulting in disruption of the kinetochore structure. Moreover, western blot analysis reveals that delocalized CENP-A molecules in HR mutants degrade in a similar fashion as in other kinetochore mutants described before. Finally, co-immunoprecipitation assays indicate that Rad51 and Rad52 physically interact with CENP-A(CACSe4) in vivo. Thus, the HR proteins Rad51 and Rad52 epigenetically maintain centromere functioning by regulating CENP-A(CACSe4) levels at the programmed stall sites of early replicating centromeres.
Description: Open Access
ISSN: 1553-7390
Appears in Collections:Research Papers (Kaustuv Sanyal)

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