CNRS - AIX MARSEILLE UNIV : UMR7257


Notre laboratoire


Le laboratoire Architecture et Fonction des Macromolécules Biologiques (AFMB), sous tutelle mixte du CNRS et de AMU, est un centre de biologie structurale localisé sur le campus de Luminy dans le Sud de Marseille, France, et en partenariat avec l’INRA sous la forme d’une unité sous contrat. L’objectif de nos recherches est de décrire à l’échelle moléculaire l’architecture des protéines ou des édifices macromoléculaires pour comprendre les mécanismes biologiques qui leur sont associés. La description des interactions entre macromolécules ou entre une macromolécule et son ligand fonctionnel est aussi nécessaire pour pouvoir agir sur ces systèmes complexes. Enfin, pour comprendre la diversité moléculaire structurale et fonctionnelle des membres de certaines familles de protéines, nous analysons les données de génomique massives issues de grands centres de séquençage


Séminaires
  • Jeudi 31 mai à 11h : Mark McBride, Department of Biological Sciences, University of Wisconsin-Milwaukee, WI, USA. "The Bacteroidetes do it differently : novel motility, protein secretion, and polysaccharide utilization machineries"

    Abstract (...)

    Abstract Flavobacterium johnsoniae and other members of the phylum Bacteroidetes have many unique features, including novel machinery for gliding motility, protein secretion, and polysaccharide utilization. Cells of Flavobacterium johnsoniae lack flagella and pili but actively move over surfaces by gliding motility. This appears unrelated to other bacterial gliding motility systems. Flavobacterium cell movement occurs when large motility adhesins, such as SprB, are rapidly propelled along the cell surface by the gliding motors, powered by the proton gradient across the cytoplasmic membrane. The adhesins travel the length of the cell along helical tracks. Binding of the adhesins to the substratum results in rotation and translocation of the cell. Cells have multiple motility adhesins allowing them to attach to and glide over diverse surfaces. The adhesins are delivered to the cell surface by the type IX protein secretion system (T9SS). T9SSs are common in but confined to the phylum Bacteroidetes. The gliding motility apparatus and the T9SS appear to be intertwined, and components of the T9SS may perform roles in both secretion and gliding. In addition to motility adhesins, T9SSs secrete many other cell-surface and soluble proteins. These include enzymes involved in digestion of polysaccharides such as cellulose and chitin and virulence factors associated with diseases of animals and humans. Secreted proteins have conserved C-terminal domains (CTDs) required for secretion. Cells can be engineered to secrete a foreign protein by attachment of such a CTD. Deletion of genes encoding T9SS components results in defects in motility, adhesion, virulence, polymer digestion, and other processes that require the secreted proteins. Bacteroidetes polysaccharide utilization often involves cell-surface proteins that bind the substrates and perform initial digestion. Long oligosaccharides are then imported across the outer membrane where further hydrolysis takes place. These and other novel features of the Bacteroidetes make this a fertile phylum for molecular exploration.
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  • Vendredi 1er Juin à 11h : Olve Peersen, Colorado State University, USA. "Structure and Fidelity Modulation of Viral RNA-dependent RNA Polymerases"

    Abstract (...)

    Abstract Positive strand RNA viruses replicate using a virally encoded RNA-dependent RNA polymerase that is responsible for both plus and minus strand RNA synthesis, using one to template the other. Our structural work with picornaviral polymerases elongation complexes have revealed that these enzymes carry out catalysis via the canonical two-metal ion polymerase mechanism, but they close their active site by a unique movement within the palm domain instead of a swinging motion within the fingers. A comprehensive comparison of polymerase structures shows this to be a universal feature of positive strand RNA virus polymerases, and structure-based mutagenesis reveals that this palm domain based movement can be used to evolutionarily fine tune replication fidelity, virus growth. and pathogenesis. Conversely, we are using protein engineering to alter polymerase fidelity and attenuate virus growth as an approach for developing live-attenuated vaccines.
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Actualités
  • En février, l’INSB a mis à l’honneur les travaux de Philippe Leone et ses collègues sur le système de sécrétion de type IX
    Voir ici
  • L’AFMB, via Isabelle Imbert et François Ferron, mis à l’honneur par l’INSB du CNRS en décembre
    Voir ici
Offre d'emploi


AFMB - UMR7257 CNRS - Aix-Marseille Univ. - Case 932
163 Avenue de Luminy 13288 Marseille CEDEX 09 FRANCE


Dernières Publications

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