title: Repetitive use of a phosphate-binding module in DNA polymerase beta, Oct-1 POU domain and phage repressors.
abstract: Motifs for sequence specific-protein-DNA interactions, such as helix-turn-helix, zinc finger and leucine zipper, are now better understood as a result of extensive studies of three-dimensional (3D) structures of transcription factors. On the other hand, little attention has been paid to motifs for sequence nonspecific binding, namely DNA-phosphate binding. To address the question whether different transcription factors and DNA manipulation enzymes, that is enzymes that work on DNA, share a similar mode of phosphate binding, we surveyed interactions between DNA and protein module, a structural unit of a globular protein. We analyzed the modular organization of DNA polymerase beta and found that residues making contact with DNA phosphates were localized to five modules. Structural comparison of these phosphate-binding modules against others in transcription factors and DNA manipulation enzymes revealed that DNA polymerase beta, the Oct-1 POU domain, 434 Cro and the Arc repressor have a phosphate-binding module with 3D structures similar to one another. This newly detected module, the phosphate-binding helix-turn-helix (pbHTH) module, named for its function and 3D structure, interacts with DNA by (i) making hydrogen bonds between a DNA phosphodiester oxygen and an amino hydrogen of the main chain located at the N-terminus of a C-terminal alpha-helix, and (ii) making electrostatic interactions between DNA phosphates and side chains of lysine or arginine. Finding structurally and functionally similar phosphate-binding units in different transcription factors and DNA manipulation enzymes suggests that shuffling of modules is not limited to the DNA base-recognition motif. Phosphate-binding modules are apparently also shuffled in DNA-binding proteins.
authors.affiliation: Division of Biological Science, Graduate School of Science, Nagoya University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Yura
authors.forename: M
authors.initials: M
authors.lastname: Shionyu
authors.forename: K
authors.initials: K
authors.lastname: Kawatani
authors.forename: M
authors.initials: M
authors.lastname: Go
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D001435:Bacteriophages / Q000737:chemistry*; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D019951:DNA Polymerase beta / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D019143:Evolution, Molecular; D018257:Helix-Loop-Helix Motifs; D051863:Host Cell Factor C1; D006860:Hydrogen Bonding; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D010710:Phosphates / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004268:DNA-Binding Proteins; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; D010710:Phosphates; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D004247:DNA; D001120:Arginine; D019951:DNA Polymerase beta; D008239:Lysine