Redox Properties and Coordination Structure of the Heme in the CO-sensing Transcriptional Activator CooA
Transcriptional Activation
0301 basic medicine
Alanine
Escherichia coli Proteins
Iron
Heme
Ligands
Spectrum Analysis, Raman
Oxygen
03 medical and health sciences
Bacterial Proteins
Models, Chemical
Electrochemistry
Mutagenesis, Site-Directed
Histidine
Cysteine
Fimbriae Proteins
Oxidation-Reduction
DOI:
10.1074/jbc.m003972200
Publication Date:
2002-07-26T15:09:37Z
AUTHORS (8)
ABSTRACT
The CO-sensing transcriptional activator CooA contains a six-coordinate protoheme as a CO sensor. Cys(75) and His(77) are assigned to the fifth ligand of the ferric and ferrous hemes, respectively. In this study, we carried out alanine-scanning mutagenesis and EXAFS analyses to determine the coordination structure of the heme in CooA. Pro(2) is thought to be the sixth ligand of the ferric and ferrous hemes in CooA, which is consistent with the crystal structure of ferrous CooA (Lanzilotta, W. N., Schuller, D. J., Thorsteinsson, M. V., Kerby, R. L., Roberts, G. P., and Poulos, T. L. (2000) Nat. Struct. Biol. 7, 876-880). CooA exhibited anomalous redox chemistry, i.e. hysteresis was observed in electrochemical redox titrations in which the observed reduction and oxidation midpoint potentials were -320 mV and -260 mV, respectively. The redox-controlled ligand exchange of the heme between Cys(75) and His(77) is thought to cause the difference between the reduction and oxidation midpoint potentials.
SUPPLEMENTAL MATERIAL
Coming soon ....
REFERENCES (65)
CITATIONS (58)
EXTERNAL LINKS
PlumX Metrics
RECOMMENDATIONS
FAIR ASSESSMENT
Coming soon ....
JUPYTER LAB
Coming soon ....