title: A new family of intrinsically disordered proteins: structural characterization of the major phasin PhaF from Pseudomonas putida KT2440.
abstract: Phasins are intracellular polyhydroxyalkanoat4e (PHA)-associated proteins involved in the stabilization of these bacterial carbon storage granules. Despite its importance in PHA metabolism and regulation, only few reports have focused so far on the structure of these proteins. In this work we have investigated the structure and stability of the PhaF phasin from Pseudomonas putida KT2440, a protein that is involved in PHA granule stabilization and distribution to daughter cells upon cell division. A structural, three-dimensional model of the protein was built from homology modeling procedures and consensus secondary structure predictions. The model predicts that PhaF is an elongated protein, with a long, amphipathic N-terminal helix with PHA binding capacity, followed by a short leucine zipper involved in protein oligomerization and a superhelical C-terminal domain wrapped around the chromosomal DNA. Hydrodynamic, spectroscopical and thermodynamic experiments validated the model and confirmed both that free PhaF is a tetramer in solution and that most part of the protein is intrinsically disordered in the absence of its ligands. The results lay a molecular basis for the explanation of the biological role of PhaF and, along with an exhaustive analysis of phasin sequence databases, suggest that intrinsic disorder and oligomerization through coiled-coils may be a widespread mechanism among these proteins.
authors: Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, Spain.
authors: Beatriz
authors: B
authors: Maestro
authors: Beatriz
authors: B
authors: Galán
authors: Carlos
authors: C
authors: Alfonso
authors: Germán
authors: G
authors: Rivas
authors: Maria A
authors: MA
authors: Prieto
authors: Jesús M
authors: JM
authors: Sanz
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D054813:Polyhydroxyalkanoates / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding / Q000187:drug effects; D016958:Pseudomonas putida; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D054813:Polyhydroxyalkanoates