TY - JOUR
T1 - The single-domain globin from the pathogenic bacterium Campylobacter jejuni
T2 - Novel D-helix conformation, proximal hydrogen bonding that influences ligand binding, and peroxidase-like redox properties
AU - Shepherd, Mark
AU - Barynin, Vladimir
AU - Lu, Changyuan
AU - Bernhardt, Paul V.
AU - Wu, Guanghui
AU - Yeh, Syun Ru
AU - Egawa, Tsuyoshi
AU - Sedelnikova, Svetlana E.
AU - Rice, David W.
AU - Wilson, Jayne Louise
AU - Poole, Robert K.
PY - 2010/4/23
Y1 - 2010/4/23
N2 - The food-borne pathogen Campylobacter jejuni possesses a single-domain globin (Cgb) whose role in detoxifying nitric oxide has been unequivocally demonstrated through genetic and molecular approaches. The x-ray structure of cyanidebound Cgb has been solved to a resolution of 1.35 Å. The overall fold is a classic three-on-three α-helical globin fold, similar to that of myoglobin and Vgb from Vitreoscilla stercoraria. However, the Dregion (defined according to the standard globin fold nomenclature) of Cgb adopts a highly ordered α-helical conformation unlike any previously characterized members of this globin family, and the GlnE7 residue has an unexpected role in modulating the interaction between the ligand and the TyrB10 residue. The proximal hydrogen bonding network in Cgb demonstrates that the heme cofactor is ligated by an imidazolate, a characteristic of peroxidase-like proteins. Mutation of either proximal hydrogen-bonding residue (GluH23 or TyrG5) results in the loss of the high frequency νFe-His stretching mode (251 cm-1), indicating that both residues are important for maintaining the anionic character of the proximal histidine ligand. Cyanide binding kinetics for these proximal mutants demonstrate for the first time that proximal hydrogen bonding in globins can modulate ligand binding kinetics at the distal site. A low redox midpoint for the ferrous/ferric couple (-134mV versus normal hydrogen electrode at pH 7) is consistent with the peroxidase-like character of the Cgb active site. These data provide a new insight into the mechanism via which Campylobacter may survive host-derived nitrosative stress.
AB - The food-borne pathogen Campylobacter jejuni possesses a single-domain globin (Cgb) whose role in detoxifying nitric oxide has been unequivocally demonstrated through genetic and molecular approaches. The x-ray structure of cyanidebound Cgb has been solved to a resolution of 1.35 Å. The overall fold is a classic three-on-three α-helical globin fold, similar to that of myoglobin and Vgb from Vitreoscilla stercoraria. However, the Dregion (defined according to the standard globin fold nomenclature) of Cgb adopts a highly ordered α-helical conformation unlike any previously characterized members of this globin family, and the GlnE7 residue has an unexpected role in modulating the interaction between the ligand and the TyrB10 residue. The proximal hydrogen bonding network in Cgb demonstrates that the heme cofactor is ligated by an imidazolate, a characteristic of peroxidase-like proteins. Mutation of either proximal hydrogen-bonding residue (GluH23 or TyrG5) results in the loss of the high frequency νFe-His stretching mode (251 cm-1), indicating that both residues are important for maintaining the anionic character of the proximal histidine ligand. Cyanide binding kinetics for these proximal mutants demonstrate for the first time that proximal hydrogen bonding in globins can modulate ligand binding kinetics at the distal site. A low redox midpoint for the ferrous/ferric couple (-134mV versus normal hydrogen electrode at pH 7) is consistent with the peroxidase-like character of the Cgb active site. These data provide a new insight into the mechanism via which Campylobacter may survive host-derived nitrosative stress.
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U2 - 10.1074/jbc.M109.084509
DO - 10.1074/jbc.M109.084509
M3 - Article
C2 - 20164176
AN - SCOPUS:77951237897
SN - 0021-9258
VL - 285
SP - 12747
EP - 12754
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 17
ER -