Two distinct pathways responsible for the loading of CENP-A to centromeres in the fission yeast cell cycle

CENP-A is a centromere-specific histone H3 variant that is- essential for faithful chromosome segregation in all eukaryotes thus far investigated. We genetically identified two factors, Ams2 and Mis6, each of which is required for the correct centromere localization of SpCENP-A (Cnp1), the fission y...

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Bibliographic Details
Published in:Philosophical transactions of the Royal Society of London. Series B. Biological sciences 2005-03, Vol.360 (1455), p.595-607
Main Authors: Takahashi, Kohta, Takayama, Yuko, Masuda, Fumie, Kobayashi, Yasuyo, Saitoh, Shigeaki
Format: Article
Language:English
Subjects:
Autoantigens - metabolism
Cell cycle
Cell Cycle - physiology
Cell Cycle Proteins - metabolism
CENP-A
Centromere
Centromere - metabolism
Centromere - physiology
Centromere Protein A
Centromeres
Chromatin
Chromatin - metabolism
Chromosomal Proteins, Non-Histone - metabolism
Chromosome Segregation
Chromosome Segregation - physiology
Chromosomes
DNA-Binding Proteins - metabolism
Fission Yeast
GATA factor
GATA Transcription Factors
Genes
Histone
Histones
Histones - metabolism
Interphase
Mitosis
Models, Biological
Nucleosomes
Schizosaccharomyces
Schizosaccharomyces pombe
Schizosaccharomyces pombe Proteins - metabolism
Yeasts
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Summary:CENP-A is a centromere-specific histone H3 variant that is- essential for faithful chromosome segregation in all eukaryotes thus far investigated. We genetically identified two factors, Ams2 and Mis6, each of which is required for the correct centromere localization of SpCENP-A (Cnp1), the fission yeast homologue of CENP-A. Ams2 is a cell-cycle-regulated GATA factor that localizes on the nuclear chromatin, including on centromeres, during the S phase. Ams2 may be responsible for the replication-coupled loading of SpCENP-A by facilitating nucleosomal formation during the S phase. Consistently, overproduction of histone H4, but not that of H3, suppressed the defect of SpCENP-A localization in Ams2-deficient cells. We demonstrated the existence of at least two distinct phases for SpCENP-A loading during the cell cycle: the S phase and the late-G2 phase. Ectopically induced SpCENP-A was efficiently loaded onto the centromeres in G2-arrested cells, indicating that SpCENP-A probably undergoes replication-uncoupled loading after the completion of S phase. This G2 loading pathway of SpCENP-A may require Mis6, a constitutive centromere-binding protein that is also implicated in the Mad2-dependent spindle attachment checkpoint response. Here, we discuss the functional relationship between the flexible loading mechanism of CENP-A and the plasticity of centromere chromatin formation in fission yeast.
ISSN:0962-8436
1471-2970
DOI:10.1098/rstb.2004.1614