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EMBO Rep. 2019 May;20(5). pii: e47183. doi: 10.15252/embr.201847183. Epub 2019 Mar 11.

Structural basis of HEAT-kleisin interactions in the human condensin I subcomplex.

Author information

1
Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan khara@u-shizuoka-ken.ac.jp hiranot@riken.jp.
2
Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan.
3
Department of Physical Biochemistry, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan.
4
Chromosome Dynamics Laboratory, RIKEN, Wako, Saitama, Japan khara@u-shizuoka-ken.ac.jp hiranot@riken.jp.

Abstract

Condensin I is a multi-protein complex that plays an essential role in mitotic chromosome assembly and segregation in eukaryotes. It is composed of five subunits: two SMC (SMC2 and SMC4), a kleisin (CAP-H), and two HEAT-repeat (CAP-D2 and CAP-G) subunits. Although balancing acts of the two HEAT-repeat subunits have been demonstrated to enable this complex to support the dynamic assembly of chromosomal axes in vertebrate cells, its underlying mechanisms remain poorly understood. Here, we report the crystal structure of a human condensin I subcomplex comprising hCAP-G and hCAP-H. hCAP-H binds to the concave surfaces of a harp-shaped HEAT-repeat domain of hCAP-G. Physical interaction between hCAP-G and hCAP-H is indeed essential for mitotic chromosome assembly recapitulated in Xenopus egg cell-free extracts. Furthermore, this study reveals that the human CAP-G-H subcomplex has the ability to interact with not only double-stranded DNA, but also single-stranded DNA, suggesting functional divergence of the vertebrate condensin I complex in proper mitotic chromosome assembly.

KEYWORDS:

HEAT repeats; HEAT‐kleisin interaction; X‐ray crystallography; chromosome condensation; ssDNA binding

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