title: Structure of a cell polarity regulator, a complex between atypical PKC and Par6 PB1 domains.
abstract: A complex of atypical PKC and Par6 is a common regulator for cell polarity-related processes, which is an essential clue to evolutionary conserved cell polarity regulation. Here, we determined the crystal structure of the complex of PKCiota and Par6alpha PB1 domains to a resolution of 1.5 A. Both PB1 domains adopt a ubiquitin fold. PKCiota PB1 presents an OPR, PC, and AID (OPCA) motif, 28 amino acid residues with acidic and hydrophobic residues, which interacts with the conserved lysine residue of Par6alpha PB1 in a front and back manner. On the interface, several salt bridges are formed including the conserved acidic residues on the OPCA motif of PKCiota PB1 and the conserved lysine residue on the Par6alpha PB1. Structural comparison of the PKCiota and Par6alpha PB1 complex with the p40phox and p67phox PB1 domain complex, subunits of neutrophil NADPH oxidase, reveals that the specific interaction is achieved by tilting the interface so that the insertion or extension in the sequence is engaged in the specificity determinant. The PB1 domain develops the interaction surface on the ubiquitin fold to increase the versatility of molecular interaction.
authors.affiliation: Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N-12, W-6, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Hirano
authors.forename: Sosuke
authors.initials: S
authors.lastname: Yoshinaga
authors.forename: Ryu
authors.initials: R
authors.lastname: Takeya
authors.forename: Nobuo N
authors.initials: NN
authors.lastname: Suzuki
authors.forename: Masataka
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Kohjima
authors.forename: Hideki
authors.initials: H
authors.lastname: Sumimoto
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Inagaki
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D016764:Cell Polarity / Q000502:physiology*; D017124:Conserved Sequence; D006706:Homeostasis; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011493:Protein Kinase C / Q000378:metabolism*; D017433:Protein Structure, Secondary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C499657:PARD6A protein, human; D011493:Protein Kinase C