title: The SUMO deconjugating peptidase Smt4 contributes to the mechanism required for transition from sister chromatid arm cohesion to sister chromatid pericentromere separation.
abstract: The pericentromere chromatin protrudes orthogonally from the sister-sister chromosome arm axis. Pericentric protrusions are organized in a series of loops with the centromere at the apex, maximizing its ability to interact with stochastically growing and shortening kinetochore microtubules. Each pericentromere loop is ∼50 kb in size and is organized further into secondary loops that are displaced from the primary spindle axis. Cohesin and condensin are integral to mechanisms of loop formation and generating resistance to outward forces from kinesin motors and anti-parallel spindle microtubules. A major unanswered question is how the boundary between chromosome arms and the pericentromere is established and maintained. We used sister chromatid separation and dynamics of LacO arrays distal to the pericentromere to address this issue. Perturbation of chromatin spring components results in 2 distinct phenotypes. In cohesin and condensin mutants sister pericentric LacO arrays separate a defined distance independent of spindle length. In the absence of Smt4, a peptidase that removes SUMO modifications from proteins, pericentric LacO arrays separate in proportion to spindle length increase. Deletion of Smt4, unlike depletion of cohesin and condensin, causes stretching of both proximal and distal pericentromere LacO arrays. The data suggest that the sumoylation state of chromatin topology adjusters, including cohesin, condensin, and topoisomerase II in the pericentromere, contribute to chromatin spring properties as well as the sister cohesion boundary.
authors.affiliation: a Department of Molecular Biosciences ; Northwestern University ; Evanston , IL USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Stephens
authors.forename: Chloe E
authors.initials: CE
authors.lastname: Snider
authors.forename: Kerry
authors.initials: K
authors.lastname: Bloom
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism; D002842:Chromatids / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D020090:Chromosome Segregation; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism*; D007763:Lac Operon / Q000235:genetics; D008938:Mitosis; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D058207:Sumoylation; D000097722:Cohesins
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004250:DNA Topoisomerases, Type II; D010450:Endopeptidases; D029701:Saccharomyces cerevisiae Proteins; D000097722:Cohesins; C405949:ULP2 protein, S cerevisiae
keywords: Smt4; Yeast; chromatin spring; cohesin; condensin; sumoylation; topoisomerase II