Local conformational transition of Hydrogenobacter thermophilus cytochrome c552 relevant to its redox potential.
In order to elucidate the molecular mechanisms responsible for the apparent nonlinear behavior of the temperature dependence of the redox potential of Hydrogenobacter thermophilus cytochrome c552 [Takahashi, Y., Sasaki, H., Takayama, S. J., Mikami, S., Kawano, S., Mita, H., Sambongi, Y., and Yamamoto, Y. (2006) Biochemistry 45, 11005-11011], its heme active site structure has been characterized using variable-temperature and -pressure NMR techniques. The study revealed a temperature-dependent conformational transition between protein structures, which slightly differ in the conformation of the loop bearing the Fe-bound axial Met residue. The heme environment in the protein structure which arises at lower temperature was found to be more polar, as a result of the altered orientation of the loop with respect to the heme due to its conformational change, than that arising at higher temperature. The present study demonstrated the importance of the structural and dynamic properties of the polypeptide chain in close proximity to the heme for redox regulation of the protein.
Takayama
Shin-ichi J
SJ
Department of Chemistry, University of Tsukuba, Tsukuba 305-8571, Japan.
Takahashi
Yo-ta
YT
Mikami
Shin-ichi
S
Irie
Kiyofumi
K
Kawano
Shin
S
Yamamoto
Yasuhiko
Y
Hemmi
Hikaru
H
Kitahara
Ryo
R
Yokoyama
Shigeyuki
S
Akasaka
Kazuyuki
K
D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D011312:Pressure; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D013696:Temperature; D013816:Thermodynamics
D001426:Bacterial Proteins; D003574:Cytochrome c Group; C022302:cytochrome C-552