Published online March 17, 2008
doi:10.1083/jcb.200710052
The Journal of Cell Biology, Vol. 180, No. 6, 1101-1114
The Rockefeller University Press, 0021-9525 $30.00
© 2008 Hemmerich et al.
Dynamics of inner kinetochore assembly and maintenance in living cells
Peter Hemmerich,
Stefanie Weidtkamp-Peters,
Christian Hoischen,
Lars Schmiedeberg,
Indri Erliandri, and
Stephan Diekmann
Leibniz Institute for Age Research, Fritz Lipmann Institute, 07745 Jena, Germany
Correspondence to P. Hemmerich: phemmer{at}fli-leibniz.de; or S. Diekmann: diekmann{at}fli-leibniz.de
To investigate the dynamics of centromere organization, we have assessed the exchange rates of inner centromere proteins (CENPs) by quantitative microscopy throughout the cell cycle in human cells. CENP-A and CENP-I are stable centromere components that are incorporated into centromeres via a "loading-only" mechanism in G1 and S phase, respectively. A subfraction of CENP-H also stays stably bound to centromeres. In contrast, CENP-B, CENP-C, and some CENP-H and hMis12 exhibit distinct and cell cycle–specific centromere binding stabilities, with residence times ranging from seconds to hours. CENP-C and CENP-H are immobilized at centromeres specifically during replication. In mitosis, all inner CENPs become completely immobilized. CENPs are highly mobile throughout bulk chromatin, which is consistent with a binding-diffusion behavior as the mechanism to scan for vacant high-affinity binding sites at centromeres. Our data reveal a wide range of cell cycle–specific assembly plasticity of the centromere that provides both stability through sustained binding of some components and flexibility through dynamic exchange of other components.
P. Hemmerich and S. Weidtkamp-Peters contributed equally to this paper.
S. Weidtkamp-Peters' present address is Institut für Physikalische Chemie II, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany.
L. Schmiedeberg's present address is Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, Scotland.
Abbreviations used in this paper: CENP, centromere protein; FCS, fluorescence correlation spectroscopy; mRFP, monomeric red fluorescent protein; PCNA, proliferating cell nuclear antigen.

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