title: A specific interdomain interaction preserves the structural and binding properties of the ModA protein from the phytopathogen Xanthomonas citri domain interaction and transport in ModA.
abstract: The periplasmic-binding proteins in ATP-binding cassette systems (ABC Transporters) are responsible for the capture and delivery of ligands to their specific transporters, triggering a series of ATP-driven conformational changes that leads to the transport of the ligand. Structurally consisting of two lobes, the proteins change conformation after interaction with the ligand. The structure of the molybdate-binding protein (ModA) from Xanthomonas citri, bound to molybdate, was previously solved by our group and an interdomain interaction, mediated by a salt bridge between K127 and D59, apparently supports the binding properties and keeps the domains closed. To determinate the importance of this interaction, we built two ModA mutants, K127S and D59A, and analysed their functional and structural properties. Based on a set of spectroscopic experiments, crystallisation trials, structure determination and molecular dynamics (MD) simulations, we showed that the salt bridge is essential to maintain the structure and binding properties. Additionally, the MD simulations revealed that this mutant adopted a more compact structure that packed down the ligand-binding pocket. From the closed bound to open structure, the positioning of the helices forming the dipole and the salt bridge are essential to induce an intermediate state.
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro de Pesquisas em Energia e Materiais (CNPEM), Campinas, SP, Brazil.
authors.forename: Carolina
authors.initials: C
authors.lastname: Santacruz-Perez
authors.forename: Vanessa Rodrigues
authors.initials: VR
authors.lastname: Pegos
authors.forename: Rodrigo V
authors.initials: RV
authors.lastname: Honorato
authors.forename: Hugo
authors.initials: H
authors.lastname: Verli
authors.forename: Erik
authors.initials: E
authors.lastname: Lindahl
authors.forename: João Alexandre Ribeiro Gonçalves
authors.initials: JA
authors.lastname: Barbosa
authors.forename: Andrea
authors.initials: A
authors.lastname: Balan
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002463:Cell Membrane Permeability; D004220:Disulfides / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D008982:Molybdenum / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013696:Temperature; D014974:Xanthomonas
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D008024:Ligands; C044659:molybdate; D008982:Molybdenum
keywords: ABC transporters; Domain interaction; ModA; Molybdate; Periplasmic-binding proteins; Xanthomonas citri