PMID- 14673090
OWN - NLM
STAT- MEDLINE
DCOM- 20040420
LR  - 20170219
IS  - 0027-8424 (Print)
IS  - 0027-8424 (Linking)
VI  - 100
IP  - 26
DP  - 2003 Dec 23
TI  - The low-spin heme of cytochrome c oxidase as the driving element of the
      proton-pumping process.
PG  - 15304-9
AB  - Mitochondrial cytochrome c oxidase plays an essential role in aerobic cellular
      respiration, reducing dioxygen to water in a process coupled with the pumping of 
      protons across the mitochondrial inner membrane. An aspartate residue, Asp-51,
      located near the enzyme surface, undergoes a redox-coupled x-ray structural
      change, which is suggestive of a role for this residue in redox-driven proton
      pumping. However, functional or mechanistic evidence for the involvement of this 
      residue in proton pumping has not yet been obtained. We report that the Asp-51
      --> Asn mutation of the bovine enzyme abolishes its proton-pumping function
      without impairment of the dioxygen reduction activity. Improved x-ray structures 
      (at 1.8/1.9-A resolution in the fully oxidized/reduced states) show that the net 
      positive charge created upon oxidation of the low-spin heme of the enzyme drives 
      the active proton transport from the interior of the mitochondria to Asp-51
      across the enzyme via a water channel and a hydrogen-bond network, located in
      tandem, and that the enzyme reduction induces proton ejection from the aspartate 
      to the mitochondrial exterior. A peptide bond in the hydrogen-bond network
      critically inhibits reverse proton transfer through the network. A redox-coupled 
      change in the capacity of the water channel, induced by the hydroxyfarnesylethyl 
      group of the low-spin heme, suggests that the channel functions as an effective
      proton-collecting region. Infrared results indicate that the conformation of
      Asp-51 is controlled only by the oxidation state of the low-spin heme. These
      results indicate that the low-spin heme drives the proton-pumping process.
FAU - Tsukihara, Tomitake
AU  - Tsukihara T
AD  - Institute for Protein Research, Osaka University, 3-2 Yamada-oka, Suita 565-0871,
      Japan.
FAU - Shimokata, Kunitoshi
AU  - Shimokata K
FAU - Katayama, Yukie
AU  - Katayama Y
FAU - Shimada, Hideo
AU  - Shimada H
FAU - Muramoto, Kazumasa
AU  - Muramoto K
FAU - Aoyama, Hiroshi
AU  - Aoyama H
FAU - Mochizuki, Masao
AU  - Mochizuki M
FAU - Shinzawa-Itoh, Kyoko
AU  - Shinzawa-Itoh K
FAU - Yamashita, Eiki
AU  - Yamashita E
FAU - Yao, Min
AU  - Yao M
FAU - Ishimura, Yuzuru
AU  - Ishimura Y
FAU - Yoshikawa, Shinya
AU  - Yoshikawa S
LA  - eng
SI  - PDB/1V54
SI  - PDB/1V55
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20031212
PL  - United States
TA  - Proc Natl Acad Sci U S A
JT  - Proceedings of the National Academy of Sciences of the United States of America
JID - 7505876
RN  - 0 (Protein Subunits)
RN  - 0 (Protons)
RN  - 30KYC7MIAI (Aspartic Acid)
RN  - 42VZT0U6YR (Heme)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Animals
MH  - Aspartic Acid
MH  - Cattle
MH  - Electron Transport Complex IV/*chemistry/*metabolism
MH  - Heme/*chemistry/*metabolism
MH  - Humans
MH  - Kinetics
MH  - Mitochondria, Heart/enzymology
MH  - Models, Molecular
MH  - Oxidation-Reduction
MH  - Protein Conformation
MH  - Protein Subunits/chemistry/metabolism
MH  - Protons
MH  - X-Ray Diffraction
PMC - PMC307562
OID - NLM: PMC307562
EDAT- 2003/12/16 05:00
MHDA- 2004/04/21 05:00
CRDT- 2003/12/16 05:00
PHST- 2003/12/16 05:00 [pubmed]
PHST- 2004/04/21 05:00 [medline]
PHST- 2003/12/16 05:00 [entrez]
AID - 10.1073/pnas.2635097100 [doi]
AID - 2635097100 [pii]
PST - ppublish
SO  - Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15304-9. doi:
      10.1073/pnas.2635097100. Epub 2003 Dec 12.