DOI: 10.1101/456798Oct 30, 2018Paper

The Molecular Basis of Monopolin Recruitment to the Kinetochore

BioRxiv : the Preprint Server for Biology
Rebecca PlowmanAdele L Marston

Abstract

In budding yeast meiosis I, the kinetochores of each sister chromatid pair are fused by the monopolin complex to mediate their monoorientation on the meiosis I spindle, enabling the biorientation and segregation of homologs. Monopolin forms a V-shaped complex with binding sites for the kinetochore protein Dsn1 at the apices of the V, suggesting that monopolin forms a physical bridge between the two sister kinetochores. Here, we reveal the molecular basis of the monopolin-kinetochore interaction and identify the key interfaces required for monopolin function at the kinetochore. The disordered N-terminus of budding-yeast Dsn1 unexpectedly possesses two binding motifs for the monopolin subunit Csm1, encompassing the previously-identified Box 1 and Box 2-3 regions of Dsn1. Strikingly, Dsn1 Box 1 and Box 2-3 bind the same conserved hydrophobic cavity on the monopolin complex subunit Csm1, suggesting that they are mutually exclusive for Csm1 binding, yet both regions are critical for monopolin function in Saccharomyces cerevisiae meiosis I. We find that Dsn1 Box 1 is an ancestral monopolin-binding motif that is conserved throughout fungi, including in the fission yeast Schizosaccharomyces pombe. In contrast, Box 2-3 is found only in ...Continue Reading

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