TY - JOUR
T1 - The proton pumping pathway of bovine heart cytochrome c oxidase
AU - Shimokata, Kunitoshi
AU - Katayama, Yukie
AU - Murayama, Haruka
AU - Suematsu, Makoto
AU - Tsukihara, Tomitake
AU - Muramoto, Kazumasa
AU - Aoyama, Hiroshi
AU - Yoshikawa, Shinya
AU - Shimada, Hideo
PY - 2007/3/6
Y1 - 2007/3/6
N2 - X-ray structures of bovine heart cytochrome c oxidase have suggested that the enzyme, which reduces O2 in a process coupled with a proton pumping process, contains a proton pumping pathway (H-pathway) composed of a hydrogen bond network and a water channel located in tandem across the enzyme. The hydrogen bond network includes the peptide bond between Tyr-440 and Ser-441, which could facilitate unidirectional proton transfer. Replacement of a possible proton-ejecting aspartate (Asp-51) at one end of the H-pathway with asparagine, using a stable bovine gene expression system, abolishes the proton pumping activity without influencing the O2 reduction function. Blockage of either the water channel by a double mutation (Val386Leu and Met390Trp) or proton transfer through the peptide by a Ser441Pro mutation was found to abolish the proton pumping activity without impairment of the O 2 reduction activity. These results significantly strengthen the proposal that H-pathway is involved in proton pumping.
AB - X-ray structures of bovine heart cytochrome c oxidase have suggested that the enzyme, which reduces O2 in a process coupled with a proton pumping process, contains a proton pumping pathway (H-pathway) composed of a hydrogen bond network and a water channel located in tandem across the enzyme. The hydrogen bond network includes the peptide bond between Tyr-440 and Ser-441, which could facilitate unidirectional proton transfer. Replacement of a possible proton-ejecting aspartate (Asp-51) at one end of the H-pathway with asparagine, using a stable bovine gene expression system, abolishes the proton pumping activity without influencing the O2 reduction function. Blockage of either the water channel by a double mutation (Val386Leu and Met390Trp) or proton transfer through the peptide by a Ser441Pro mutation was found to abolish the proton pumping activity without impairment of the O 2 reduction activity. These results significantly strengthen the proposal that H-pathway is involved in proton pumping.
KW - HeLa cell
KW - Keto-enol tautomerism
KW - Mitochondrial import
KW - Mutagenesis
KW - Peptide bond
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U2 - 10.1073/pnas.0611627104
DO - 10.1073/pnas.0611627104
M3 - Article
C2 - 17360500
AN - SCOPUS:34247180567
SN - 0027-8424
VL - 104
SP - 4200
EP - 4205
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 10
ER -