title: An NMR-based identification of a peptide fragment from the beta-subunit of a G-protein showing specific interactions with the GBB domain of the Ste20 kinase in budding yeast.
abstract: In mitogen-activated protein kinase (MAPK) cascades of budding yeast, pheromone-induced mating signal is transmitted by interactions between the beta-subunit of a G-protein (G-beta) and the G-beta binding (GBB) domain of Ste20 kinase. Previously, mutational analyses of the beta-subunit of G-protein had identified two critical mutations which abrogate binding of the GBB domain of Ste20. In this work, we have identified, by use of NMR spectroscopy, a peptide fragment from the G-beta that shows specific interactions with the isolated GBB domain of Ste20. A model structure of the Ste20/G-beta complex reveals that the interface of the hetero-complex may be sustained by parallel orientation of two potentially interacting helical segments that are further stabilized by ionic, hydrogen bond, and helix macro-dipole interactions.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore. surajit@ntu.edu.sg
authors.forename: Surajit
authors.initials: S
authors.lastname: Bhattacharjya
authors.forename: Richard
authors.initials: R
authors.lastname: Gingras
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D020930:MAP Kinase Kinase Kinases; D020935:MAP Kinase Signaling System / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D044387:GTP-Binding Protein beta Subunits; D047908:Intracellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae