Structural evidence for a proton transfer pathway coupled with haem reduction of cytochrome c" from Methylophilus methylotrophus.
The crystal structures of the oxidized and reduced forms of cytochrome c" from Methylophilus methylotrophus were solved from X-ray synchrotron data to atomic resolution. The overall fold of the molecule in the two redox states is very similar and is comparable to that of the oxygen-binding protein from the purple phototrophic bacterium Rhodobacter sphaeroides. However, significant modifications occur near the haem group, in particular the detachment from axial binding of His95 observed upon reduction as well as the adoption of different conformations of some protonatable residues that form a possible proton path from the haem pocket to the protein surface. These changes are associated with the previously well characterized redox-Bohr behaviour of this protein. Furthermore they provide a model for one of the presently proposed mechanisms of proton translocation in the much more complex protein cytochrome c oxidase.
Enguita
Francisco J
FJ
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, P.O. Box 127, 2781-901 Oeiras, Portugal.
Pohl
Ehmke
E
Turner
David L
DL
Santos
Helena
H
Carrondo
Maria Arménia
MA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry* / Q000235:genetics; D006418:Heme / Q000737:chemistry*; D020630:Methylophilus methylotrophus / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011487:Protein Conformation; D011522:Protons; D016415:Sequence Alignment
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D011522:Protons; C076615:cytochrome c''; D006418:Heme