title: Conserved disruptions in the predicted coiled-coil domains of eukaryotic SMC complexes: implications for structure and function.
abstract: The structural maintenance of chromosome (SMC) proteins are required for a number of essential nuclear processes, including those of chromosome condensation, chromatid cohesion, and DNA repair. Eukaryotic SMC proteins form heterodimers capable of binding DNA and possess a DNA-stimulated ATPase activity. They have a characteristic structure of terminal globular domains with two internal arms that are predicted to form a coiled-coil structure interspaced with a globular "hinge" domain. We report here that the predicted coiled-coil arms are disrupted at conserved sites in SMC proteins. These disruptions, which vary in length and sequence identity, abolish the otherwise symmetrical secondary structure of antiparallel SMC heterodimers and provide the first evidence for a possible functional orientation of eukaryotic SMC complexes. The retention of these breaks between evolutionarily distant, yet related, SMC members indicates that they may have a fundamental role in SMC heterodimer function.
authors.affiliation: Peter MacCallum Cancer Institute, East Melbourne, Victoria 3002, Australia.
authors.forename: Matthew
authors.initials: M
authors.lastname: Beasley
authors.forename: Huiling
authors.initials: H
authors.lastname: Xu
authors.forename: William
authors.initials: W
authors.lastname: Warren
authors.forename: Michael
authors.initials: M
authors.lastname: McKay
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics*; D011508:Chondroitin Sulfate Proteoglycans; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics*; D017124:Conserved Sequence / Q000235:genetics*; D019281:Dimerization; D029721:Drosophila Proteins / Q000235:genetics; D005057:Eukaryotic Cells / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D017433:Protein Structure, Secondary / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D029867:Xenopus Proteins / Q000235:genetics; D000098550:Structural Maintenance of Chromosome Protein 1
chemical_list: D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D011508:Chondroitin Sulfate Proteoglycans; D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; D005656:Fungal Proteins; D009687:Nuclear Proteins; C090455:SMC2 protein, S cerevisiae; C120372:SMC3 protein, S cerevisiae; C492318:SMC3 protein, human; C409162:SMC4 protein, S cerevisiae; C486627:SMC5 protein, S cerevisiae; C432931:SMC5 protein, human; C486631:SMC6 protein, S cerevisiae; C432932:SMC6 protein, human; D029701:Saccharomyces cerevisiae Proteins; D029867:Xenopus Proteins; D000098550:Structural Maintenance of Chromosome Protein 1