title: Evolution of condensin and cohesin complexes driven by replacement of Kite by Hawk proteins.
abstract: Mitotic chromosome condensation, sister chromatid cohesion, and higher order folding of interphase chromatin are mediated by condensin and cohesin, eukaryotic members of the SMC (structural maintenance of chromosomes)-kleisin protein family. Other members facilitate chromosome segregation in bacteria [1]. A hallmark of these complexes is the binding of the two ends of a kleisin subunit to the apices of V-shaped Smc dimers, creating a tripartite ring capable of entrapping DNA (Figure 1A). In addition to creating rings, kleisins recruit regulatory subunits. One family of regulators, namely Kite dimers (Kleisin interacting winged-helix tandem elements), interact with Smc-kleisin rings from bacteria, archaea and the eukaryotic Smc5-6 complex, but not with either condensin or cohesin [2]. These instead possess proteins containing HEAT (Huntingtin/EF3/PP2A/Tor1) repeat domains whose origin and distribution have not yet been characterized. Using a combination of profile Hidden Markov Model (HMM)-based homology searches, network analysis and structural alignments, we identify a common origin for these regulators, for which we propose the name Hawks, i.e. HEAT proteins associated with kleisins.
authors.affiliation: MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Wells
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK. Electronic address: thomas.gligoris@bioch.ox.ac.uk.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Gligoris
authors.affiliation: Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Nasmyth
authors.affiliation: MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK. Electronic address: authorjoseph.marsh@igmm.ed.ac.uk.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Marsh
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D020090:Chromosome Segregation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D056890:Eukaryota / Q000378:metabolism*; D019143:Evolution, Molecular; D008390:Markov Chains; D008938:Mitosis; D046912:Multiprotein Complexes / Q000378:metabolism*; D000097722:Cohesins
chemical_list: D000251:Adenosine Triphosphatases; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D000097722:Cohesins; C108312:condensin complexes