title: Molecular basis of sequence-specific single-stranded DNA recognition by KH domains: solution structure of a complex between hnRNP K KH3 and single-stranded DNA.
abstract: To elucidate the basis of sequence-specific single-stranded (ss) DNA recognition by K homology (KH) domains, we have solved the solution structure of a complex between the KH3 domain of the transcriptional regulator heterogeneous nuclear ribonucleoprotein K (hnRNP K) and a 10mer ssDNA. We show that hnRNP K KH3 specifically recognizes a tetrad of sequence 5'd-TCCC. The complex is stabilized by a dense network of methyl-oxygen hydrogen bonds involving the methyl groups of three isoleucine residues and the O2 and N3 atoms of the two central cytosine bases. Comparison with the recently solved structure of a specific protein-ssDNA complex involving the KH3 and KH4 domains of the far upstream element (FUSE) binding protein FBP suggests that the amino acid located five residues N-terminal of the invariant GXXG motif, which is characteristic of all KH domains, plays a crucial role in discrimination of the first two bases of the tetrad.
authors.affiliation: Laboratory of Chemical Physics, Building 5, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0510, USA.
authors.forename: Demetrios T
authors.initials: DT
authors.lastname: Braddock
authors.forename: James L
authors.initials: JL
authors.lastname: Baber
authors.forename: David
authors.initials: D
authors.lastname: Levens
authors.forename: G Marius
authors.initials: GM
authors.lastname: Clore
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D018360:Crystallography, X-Ray; D004265:DNA Helicases; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D006801:Humans; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D013379:Substrate Specificity
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C492258:FUBP1 protein, human; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D012996:Solutions; D004265:DNA Helicases