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6 juin 2018: 1 événement

  • Département Microbiologie

    Mercredi 6 juin 2018 11:30-13:00 - Dr. Marianne Ilbert - « Métabolisme énergétique des bactéries extrémophiles » Bioénergétique et Ingénierie des Protéines (BIP), Marseille

    Bacterial life in acid ? Toward a better understanding of an iron respiratory chain working at pH 2

    Résumé : Microorganisms are found in various ecosystems, where they have this incredible ability to adapt to challenging conditions. Acidithiobacillus ferrooxidans, a gram negative bacterium, is the most studied and relevant model to understand how to survive in harmful environments with pH as low as pH 2 and high level of toxic metals, getting energy source from minerals containing iron and sulfur. This remarkable ability to gain energy through oxidation of ferrous iron at low pH has driven a lot of interest because of application in microbial leaching. We are currently studying the iron respiratory chain of this acidophilic organism by a multidisciplinary approach. Several metalloproteins have been identified and characterized, but the electron transfer pathway from the outer membrane to the inner membrane cytochrome c oxidase is still obscure.
    During this seminar, we will first focus our attention on the newly identified cupredoxin, AcoP, which contains a green-type copper center. We will present the crystal structure of AcoP and will discuss its spectroscopic features underlying some unexpected properties. Key residues were targeted by site directed mutagenesis to better understand the determinants driving these unusual properties. In addition, we are currently reconstituting parts of the respiratory chain with the aim to determine step by step the electron transfer pathway. The strategy is to study purified AcoP, di-heme cytochrome c and cytochrome c oxidase alone or incubated together in solution or in the immobilized state at an electrode mimicking one of the partner. Beyond thermodynamic data for each protein, this methodology offers the opportunity to decipher the molecular basis of protein-protein interaction favorable to electron transfer at low pH (A. ferrooxidans periplasmic compartment is estimated at pH 2.5). This should allow us to further describe the function of each protein in this energy chain.
    Invitée par l’équipe Adaptation bactérienne aux changements environnementaux
    Contact : Anne Durand

    Lieu : Salle Kalogeropoulos - Bâtiment 400, Campus d’Orsay

    En savoir plus : Département Microbiologie