Phosphoserines on maize CENTROMERIC HISTONE H3 and histone H3 demarcate the centromere and pericentromere during chromosome segregation.
We have identified and characterized a 17- to 18-kD Ser50-phosphorylated form of maize (Zea mays) CENTROMERIC HISTONE H3 (phCENH3-Ser50). Immunostaining in both mitosis and meiosis indicates that CENH3-Ser50 phosphorylation begins in prophase/diplotene, increases to a maximum at prometaphase-metaphase, and drops during anaphase. Dephosphorylation is precipitous (approximately sixfold) at the metaphase-anaphase transition, suggesting a role in the spindle checkpoint. Although phCENH3-Ser50 lies within a region that lacks homology to any other known histone, its closest counterpart is the phospho-Ser28 residue of histone H3 (phH3-Ser28). CENH3-Ser50 and H3-Ser28 are phosphorylated with nearly identical kinetics, but the former is restricted to centromeres and the latter to pericentromeres. Opposing centromeres separate in prometaphase, whereas the phH3-Ser28-marked pericentromeres remain attached and coalesce into a well-defined tether that binds the centromeres together. We propose that a centromere-initiated wave of histone phosphorylation is an early step in defining the two major structural domains required for chromosome segregation: centromere (alignment, motility) and pericentromere (cohesion).
Zhang
Xiaolan
X
Department of Plant Biology, University of Georgia, Athens, Georgia 30602, USA.
Li
Xuexian
X
Marshall
Joshua B
JB
Zhong
Cathy X
CX
Dawe
R Kelly
RK
D000595:Amino Acid Sequence; D002503:Centromere / Q000378:metabolism*; D020090:Chromosome Segregation; D032461:Chromosomes, Plant / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000378:metabolism*
D006657:Histones; D010940:Plant Proteins; D010768:Phosphoserine