Centromere localization and function of Mis18 requires Yippee‐like domain‐mediated oligomerization

Abstract

© 2016 The Authors. Published under the terms of the CC BY 4.0 license. Mis18 is a key regulator responsible for the centromere localization of the CENP-A chaperone Scm3 in Schizosaccharomyces pombe and HJURP in humans, which establishes CENP-A chromatin that defines centromeres. The molecular and structural determinants of Mis18 centromere targeting remain elusive. Here, by combining structural, biochemical, and yeast genetic studies, we show that the oligomerization of S. pombe Mis18, mediated via its conserved N-terminal Yippee-like domain, is crucial for its centromere localization and function. The crystal structure of the N-terminal Yippee-like domain reveals a fold containing a cradle-shaped pocket that is implicated in protein/nucleic acid binding, which we show is required for Mis18 function. While the N-terminal Yippee-like domain forms a homodimer in vitro and in vivo, full-length Mis18, including the C-terminal α-helical domain, forms a homotetramer in vitro. We also show that the Yippee-like domains of human Mis18α/Mis18β interact to form a heterodimer, implying a conserved structural theme for Mis18 regulation. Synopsis This study presents the structural characterization of Mis18, a key regulator responsible for the centromere localization of the CENP-A-specific chaperone HJURP in humans and Scm3 in S. pombe. While the conserved N-terminal "Yippee-like" domain possesses an intrinsic ability to dimerize, the full-length S. pombe Mis18 forms a tetramer and this oligomeric structure, mediated via its "Yippee-like" domain, is crucial for Mis18 centromere localization and function. S. pombe Mis18 possesses two structurally distinct domains: an N-terminal "Yippee-like" globular domain and a C-terminal α-helical domain. While N-terminal "Yippee-like" domain possesses an intrinsic ability to homodimerize, the full-length Mis18 forms a tetramer in vitro. Mutations disrupting the dimerization of "Yippee-like" domain reduce Mis18 centromere localization and compromise its function. This study presents the structural characterization of Mis18, a key regulator responsible for the centromere localization of the CENP-A-specific chaperone HJURP in humans and Scm3 in S. pombe. While the conserved N-terminal "Yippee-like" domain possesses an intrinsic ability to dimerize, the full-length S. pombe Mis18 forms a tetramer and this oligomeric structure, mediated via its "Yippee-like" domain, is crucial for Mis18 centromere localization and function.