title: Condensin architecture and interaction with DNA: regulatory non-SMC subunits bind to the head of SMC heterodimer.
abstract: Condensin and cohesin are two protein complexes that act as the central mediators of chromosome condensation and sister chromatid cohesion, respectively. The basic underlying mechanism of action of these complexes remained enigmatic. Direct visualization of condensin and cohesin was expected to provide hints to their mechanisms. They are composed of heterodimers of distinct structural maintenance of chromosome (SMC) proteins and other non-SMC subunits. Here, we report the first observation of the architecture of condensin and its interaction with DNA by atomic force microscopy (AFM). The purified condensin SMC heterodimer shows a head-tail structure with a single head composed of globular domains and a tail with the coiled-coil region. Unexpectedly, the condensin non-SMC trimers associate with the head of SMC heterodimers, producing a larger head with the tail. The heteropentamer is bound to DNA in a distributive fashion, whereas condensin SMC heterodimers interact with DNA as aggregates within a large DNA-protein assembly. Thus, non-SMC trimers may regulate the ATPase activity of condensin by directly interacting with the globular domains of SMC heterodimer and alter the mode of DNA interaction. A model for the action of heteropentamer is presented.
authors.affiliation: CREST Research Project, Department of Responses to Environmental Signals and Stresses, Graduate School of Biostudies, Kyoto University, Japan.
authors.forename: Shige H
authors.initials: SH
authors.lastname: Yoshimura
authors.forename: Kohji
authors.initials: K
authors.lastname: Hizume
authors.forename: Akiko
authors.initials: A
authors.lastname: Murakami
authors.forename: Takashi
authors.initials: T
authors.lastname: Sutani
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yanagida
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002875:Chromosomes; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D046912:Multiprotein Complexes; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D011994:Recombinant Proteins; C108312:condensin complexes; D004247:DNA; D000251:Adenosine Triphosphatases