Molecular basis for inner kinetochore configuration through RWD domain-peptide interactions.
Publication Type:Journal Article
Source:EMBO J, Volume 36, Issue 23, p.3458-3482 (2017)
Keywords:Amino Acid Sequence, Centromere, Chromosomal Proteins, Non-Histone, Deuterium Exchange Measurement, Fungal Proteins, Humans, Kinetochores, Kluyveromyces, Mitosis, Models, Molecular, Multiprotein Complexes, Mutation, Protein Interaction Domains and Motifs, Protein Subunits, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Spectrometry, Mass, Electrospray Ionization
<p>Kinetochores are dynamic cellular structures that connect chromosomes to microtubules. They form from multi-protein assemblies that are evolutionarily conserved between yeasts and humans. One of these assemblies-COMA-consists of subunits Ame1, Ctf19, Mcm21 and Okp1 A description of COMA molecular organization has so far been missing. We defined the subunit topology of COMA, bound with inner kinetochore proteins Nkp1 and Nkp2, from the yeast , with nanoflow electrospray ionization mass spectrometry, and mapped intermolecular contacts with hydrogen-deuterium exchange coupled to mass spectrometry. Our data suggest that the essential Okp1 subunit is a multi-segmented nexus with distinct binding sites for Ame1, Nkp1-Nkp2 and Ctf19-Mcm21. Our crystal structure of the Ctf19-Mcm21 RWD domains bound with Okp1 shows the molecular contacts of this important inner kinetochore joint. The Ctf19-Mcm21 binding motif in Okp1 configures a branch of mitotic inner kinetochores, by tethering Ctf19-Mcm21 and Chl4-Iml3 Absence of this motif results in dependence on the mitotic checkpoint for viability.</p>