title: Molecular recognition in dimerization between PB1 domains.
abstract: The PB1 (Phox and Bem 1) domain is a recently identified module that mediates formation of a heterodimeric complex with other PB1 domain, e.g. the complexes between the phagocyte oxidase activators p67phox and p40phox and between the yeast polarity proteins Bem1p and Cdc24p. These PB1 domains harbor either a conserved lysine residue on one side or an acidic OPCA (OPR/PC/AID) motif around the other side; the lysine of p67phox or Bem1p likely binds to the OPCA of p40phox or Cdc24p, respectively, via electrostatic interactions. To further understand molecular recognition by PB1 domains, here we investigate the interactions mediated by proteins presenting both the lysine and OPCA on a single PB1 domain, namely Par6, atypical protein kinase C (aPKC), and ZIP. Par6 and aPKC form a complex via the interaction of the Par6 lysine with aPKC-OPCA but not via that between the aPKC lysine and Par6-OPCA, thereby localizing to the tight junction of epithelial cells. aPKC also uses its OPCA to interact with ZIP, another protein that has a PB1 domain presenting both the lysine and OPCA, whereas aPKC binds via the conserved lysine to MEK5 in the same manner as ZIP interacts with MEK5. In addition, ZIP can form a homotypic complex via the conserved electrostatic interactions. Thus the PB1 domain appears to be a protein module that fully exploits its two mutually interacting elements in molecular recognition to expand its repertoire of protein-protein interactions.
authors.affiliation: Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Noda
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Kohjima
authors.forename: Tomoko
authors.initials: T
authors.lastname: Izaki
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Ota
authors.forename: Sosuke
authors.initials: S
authors.lastname: Yoshinaga
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Inagaki
authors.forename: Takashi
authors.initials: T
authors.lastname: Ito
authors.forename: Hideki
authors.initials: H
authors.lastname: Sumimoto
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D019281:Dimerization; D004285:Dogs; D004847:Epithelial Cells / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010750:Phosphoproteins / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000737:chemistry; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D019108:Tight Junctions; D014162:Transfection; D020798:Two-Hybrid System Techniques
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018076:DNA, Complementary; D010750:Phosphoproteins; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; C085072:neutrophil cytosol factor 40K; C079789:neutrophil cytosol factor 67K; C073129:BEM1 protein, S cerevisiae; D011493:Protein Kinase C; D008239:Lysine