title: Binding of the concave surface of the Sds22 superhelix to the alpha 4/alpha 5/alpha 6-triangle of protein phosphatase-1.
abstract: Functional studies of the protein phosphatase-1 (PP1) regulator Sds22 suggest that it is indirectly and/or directly involved in one of the most ancient functions of PP1, i.e. reversing phosphorylation by the Aurora-related protein kinases. We predict that the conserved portion of Sds22 folds into a curved superhelix and demonstrate that mutation to alanine of any of eight residues (Asp(148), Phe(170), Glu(192), Phe(214), Asp(280), Glu(300), Trp(302), or Tyr(327)) at the concave surface of this superhelix thwarts the interaction with PP1. Furthermore, we show that all mammalian isoforms of PP1 have the potential to bind Sds22. Interaction studies with truncated versions of PP1 and with chimeric proteins comprising fragments of PP1 and the yeast PP1-like protein phosphatase Ppz1 suggest that the site(s) required for the binding of Sds22 reside between residues 43 and 173 of PP1gamma(1). Within this region, a major interaction site was mapped to a triangular region delineated by the alpha4-, alpha5-, and alpha6-helices. Our data also show that well known regulatory binding sites of PP1, such as the RVXF-binding channel, the beta12/beta13-loop, and the acidic groove, are not essential for the interaction with Sds22.
authors.affiliation: Afdeling Biochemie, Faculteit Geneeskunde, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium. Hugo.Ceulemans@med.kuleuven.ac.be
authors.forename: Hugo
authors.initials: H
authors.lastname: Ceulemans
authors.forename: Veerle
authors.initials: V
authors.lastname: Vulsteke
authors.forename: Marc
authors.initials: M
authors.lastname: De Maeyer
authors.forename: Kelly
authors.initials: K
authors.lastname: Tatchell
authors.forename: Willy
authors.initials: W
authors.lastname: Stalmans
authors.forename: Mathieu
authors.initials: M
authors.lastname: Bollen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D019556:COS Cells; D020134:Catalytic Domain; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D017124:Conserved Sequence; D019992:Databases as Topic; D017353:Gene Deletion; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins; D010749:Phosphoprotein Phosphatases / Q000737:chemistry* / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017510:Protein Folding; D020033:Protein Isoforms; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D011817:Rabbits; D051381:Rats; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; C509753:Ppp1r7 protein, rat; D020033:Protein Isoforms; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D001616:beta-Galactosidase