Structural Biochemistry - CNRS URA 2185  

  HEADProf. ALZARI Pedro /
  MEMBERSDr ALBANESI Daniela / Dr ANDRE-LEROUX Gwénaëlle / ARBOGAST Laurence / Dr BELLINZONI Marco / Dr BETTON Jean-Michel / Dr ENGLAND Patrick / FRAYSSE Jocelyne
GRANA Martin / Dr GUERIN Marcelo / HINDIE Valérie / Dr. MIOT Marie-Caroline / Dr OPPEZZO Pablo / SASSOON-CLAVIER Nathalie
Dr SCHAEFFER Francis / TELLO Diana / WAGNER Tristan / Dr. WEHENKEL Anne-Marie

  Annual Report

Our research activities are oriented towards the biochemical, biophysical and structural studies of proteins involved in microbial pathogenesis. Some ongoing projects are described below; additional information can be found in our Web page:

Ser/Thr phosphorylation in mycobacteria Although bacterial signaling mechanisms involve primarily the action of two-component systems, the genome of M. tuberculosis revealed the presence of several genes coding for eukaryotic-like Ser/Thr protein kinases and phosphatases. We have determined the 3D structures of the kinase PknB and the phosphatase PstP, both coded by a conserved operon that controls mycobacterial cell division, and the atomic resolution structure of a second mycobacterial phosphatase MspP, which provided new important insights into the catalytic mechanism of this large class of enzymes (Figure 1). We also showed that the pknB gene is essential for TB growth and that inhibitors targeting PknB could represent promising compounds with potential therapeutic applications. Our efforts are now focused on elucidating the PknB-mediated signalling pathway(s) and developing specific inhibitors of PknB and other TB targets.

Global regulation of lipid biosynthesis in bacteria. We have recently showed that malonyl-CoA is the specific effector of FapR, a global regulator of fatty acid synthesis in various Gram+ bacteria, and we are carrying out structural and thermodynamic studies of FapR-effector-DNA complexes from different bacteria (B. subtilis, S. aureus, L. monocytogenes). The mode of action involves an effector-induced disorder-to-order transition in FapR that dissociates the protein from its DNA operator. Structure-based mutants that impair effector binding were shown to abolish regulation in vivo and result in a lethal (super-repressor) phenotype in B. subtilis. Our current studies are focused on human pathogens such as S. aureus and L. monocytogenes, to understand their mode of action and validate this homeostatic pathway as a potential therapeutic target.

Protein folding and secretion mechanisms in bacteria (J.M. Betton) Our group studies bacterial quality control systems for the development of more efficient protein expression processes. If they escape the cellular quality-control systems, proteins may aggregate when E. coli cells are exposed to environmental stress or overexpress recombinant genes (protein factories). The CpxA/R signal transduction system senses perturbations in the periplasm and responds by up-regulating several protein folding and degrading activities. For these studies we use cell-free expression systems to express membrane proteins in the presence of detergent micelles. Current projects include the function of the periplasmic protease DegP/HtrA, and biochemical and structural analysis of proteins involved in the CpxA/R system.

Keywords: Mycobacterium tuberculosis, bacterial signaling, protein kinases and phosphatases, regulation of lipid biosynthesis, drug design, bacterial protein expression, X-ray crystallography, microcalorimetry, structural biology


Three-metal catalytic center of mycobacterial Ser/Thr protein phosphatases

Activity Reports 2007 - Institut Pasteur
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