tailieunhanh - Báo cáo khoa học: Basis of recognition between the NarJ chaperone and the N-terminus of the NarG subunit from Escherichia coli nitrate reductase

A novel class of molecular chaperones co-ordinates the assembly and targeting of complex metalloproteins by binding to an amino-terminal peptide of the cognate substrate. We have previously shown that the NarJ chaperone interacts with the N-terminus of the NarG subunit coming from the nitrate reductase complex, NarGHI. | Basis of recognition between the NarJ chaperone and the N-terminus of the NarG subunit from Escherichia coli nitrate reductase Silva Zakian1 Daniel Lafitte2 Alexandra Vergnes1 Cyril Pimentel3 Corinne Sebban-Kreuzer3 Rene Toci1 Jean-Baptiste Claude4 Francoise Guerlesquin3 and Axel Magalon1 1 Laboratoire de Chimie Bacterienne Institut de Microbiologie de la Méditerranée Centre Nationalde la Recherche Scientifique Marseille France 2 MaP site Timone UMR INSERM 911 Universite d Aix-Marseille II France 3 Interactions et Modulateurs de Reponses Institut de Microbiologie de la Mediterranee Centre Nationalde la Recherche Scientifique Marseille France 4 Information Genomique et Structurale Marseille France Keywords chaperone metalloproteins nitrate reductase NMR translocation Correspondence A. Magalon Laboratoire de Chimie Bacterienne Institut de Microbiologie de la Mediterranee Centre Nationalde la Recherche Scientifique 31 chemin Joseph Aiguier 13402 Marseille Cedex 09 France Fax 33 491 718 914 Tel 33 491 164 668 E-mail magalon@ Received 8 December 2009 revised 25 January 2010 accepted 4 February 2010 doi A novel class of molecular chaperones co-ordinates the assembly and targeting of complex metalloproteins by binding to an amino-terminal peptide of the cognate substrate. We have previously shown that the NarJ chaperone interacts with the N-terminus of the NarG subunit coming from the nitrate reductase complex NarGHI. In the present study NMR structural analysis revealed that the NarG 1-15 peptide adopts an a-helical conformation in solution. Moreover NarJ recognizes and binds the helical NarG 1-15 peptide mostly via hydrophobic interactions as deduced from isothermal titration calorimetry analysis. NMR and differential scanning calorimetry analysis revealed a modification of NarJ conformation during complex formation with the NarG 1-15 peptide. Isothermal titration calorimetry and BIAcore experiments support a model .