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. In the present study, NMR structural analysis revealed that the NarG(1-15) peptide adopts an alpha-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 whereby the protonated state of the chaperone controls the time dependence of peptide interaction.
Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique, Marseille, France.
Silva
S
Zakian
Daniel
D
Lafitte
Alexandra
A
Vergnes
Cyril
C
Pimentel
Corinne
C
Sebban-Kreuzer
René
R
Toci
Jean-Baptiste
JB
Claude
Françoise
F
Guerlesquin
Axel
A
Magalon
D001665:Binding Sites / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050901:Nitrate Reductase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D055672:Static Electricity; D013816:Thermodynamics
D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D050901:Nitrate Reductase