title: The structural basis of DNA binding by the single-stranded DNA-binding protein from Sulfolobus solfataricus.
abstract: Canonical single-stranded DNA-binding proteins (SSBs) from the oligosaccharide/oligonucleotide-binding (OB) domain family are present in all known organisms and are critical for DNA replication, recombination and repair. The SSB from the hyperthermophilic crenarchaeote Sulfolobus solfataricus (SsoSSB) has a 'simple' domain organization consisting of a single DNA-binding OB fold coupled to a flexible C-terminal tail, in contrast with other SSBs in this family that incorporate up to four OB domains. Despite the large differences in the domain organization within the SSB family, the structure of the OB domain is remarkably similar all cellular life forms. However, there are significant differences in the molecular mechanism of ssDNA binding. We have determined the structure of the SsoSSB OB domain bound to ssDNA by NMR spectroscopy. We reveal that ssDNA recognition is modulated by base-stacking of three key aromatic residues, in contrast with the OB domains of human RPA and the recently discovered human homologue of SsoSSB, hSSB1. We also demonstrate that SsoSSB binds ssDNA with a footprint of five bases and with a defined binding polarity. These data elucidate the structural basis of DNA binding and shed light on the molecular mechanism by which these 'simple' SSBs interact with ssDNA.
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Roland
authors.initials: R
authors.lastname: Gamsjaeger
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Ruvini
authors.initials: R
authors.lastname: Kariawasam
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Adrian X
authors.initials: AX
authors.lastname: Gimenez
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Touma
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Elysse
authors.initials: E
authors.lastname: McIlwain
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Ray E
authors.initials: RE
authors.lastname: Bernardo
authors.affiliation: †School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Shepherd
authors.affiliation: †School of Molecular Bioscience, University of Sydney, Sydney, NSW 2006, Australia.
authors.forename: Sandro F
authors.initials: SF
authors.lastname: Ataide
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Qihan
authors.initials: Q
authors.lastname: Dong
authors.affiliation: §Institute of Health and Biomedical Innovation, Translational Research Institute, Queensland University of Technology, Woolloongabba 4102, Australia.
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Richard
authors.affiliation: ║Biomolecular Sciences Research Complex, University of St Andrews, St Andrews, KY16 9ST, U.K.
authors.forename: Malcolm F
authors.initials: MF
authors.lastname: White
authors.affiliation: *School of Science and Health, University of Western Sydney, Penrith, NSW 2751, Australia.
authors.forename: Liza
authors.initials: L
authors.lastname: Cubeddu
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D019641:DNA, Archaeal / Q000737:chemistry* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D048229:Sulfolobus solfataricus / Q000737:chemistry* / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D019641:DNA, Archaeal; D004268:DNA-Binding Proteins