title: Structural analysis of the HiPIP from the acidophilic bacteria: Acidithiobacillus ferrooxidans.
abstract: Hip is a high-potential iron-sulfur protein (HiPIP) isolated from the acidophilic bacterium, Acidithiobacillus ferrooxidans. In the present work, a structural model of Hip suggests that the role of proline residues is essential to stabilize the protein folding at very low pH. The presence of an unusual disulfide bridge in Hip is demonstrated using mass spectrometry and nuclear magnetic resonance. This disulfide bridge is necessary to anchor the N-terminal extremity of the protein, but is not involved in the acid stability of Hip. The structural parameters correlated with the pH dependence of Hip redox potential are also analysed on the basis of this model. Given that the same structural features can enhance acidic stability and lead to elevated redox potentials, modulation of the redox potentials of electron carriers may be necessary to achieve electron transfer at very low pH.
authors.affiliation: Unité de Bioénergétique et Ingénierie des Protéines, CNRS, 31 chemin Joseph Aiguier, 13402 Marseille, Cedex 20, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Nouailler
authors.forename: Patrice
authors.initials: P
authors.lastname: Bruscella
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Lojou
authors.forename: Régine
authors.initials: R
authors.lastname: Lebrun
authors.forename: Violaine
authors.initials: V
authors.lastname: Bonnefoy
authors.forename: Françoise
authors.initials: F
authors.lastname: Guerlesquin
mesh_terms: D042763:Acidithiobacillus / Q000737:chemistry* / Q000378:metabolism*; D000143:Acids; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D017124:Conserved Sequence; D004220:Disulfides / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000378:metabolism*; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism*; D011489:Protein Denaturation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment
chemical_list: D000143:Acids; D001426:Bacterial Proteins; D004220:Disulfides; D007506:Iron-Sulfur Proteins; D008024:Ligands; D045322:Photosynthetic Reaction Center Complex Proteins; C007943:high potential iron-sulfur protein