PMID- 18847227
OWN - NLM
STAT- MEDLINE
DCOM- 20081112
LR  - 20231105
IS  - 1520-4995 (Electronic)
IS  - 0006-2960 (Print)
IS  - 0006-2960 (Linking)
VI  - 47
IP  - 44
DP  - 2008 Nov 4
TI  - Proton-dependent electron transfer from CuA to heme a and altered EPR spectra in 
      mutants close to heme a of cytochrome oxidase.
PG  - 11499-509
LID - 10.1021/bi801156s [doi]
AB  - Eukaryotic cytochrome c oxidase (CcO) and homologous prokaryotic forms of 
      Rhodobacter and Paraccocus differ in the EPR spectrum of heme a. It was noted 
      that a histidine ligand of heme a (H102) is hydrogen bonded to serine in 
      Rhodobacter (S44) and Paraccocus CcOs, in contrast to glycine in the bovine 
      enzyme. Mutation of S44 to glycine shifts the heme a EPR signal from g(z) = 2.82 
      to 2.86, closer to bovine heme a at 3.03, without modifying other properties. 
      Mutation to aspartate, however, results in an oppositely shifted and split heme a 
      EPR signal of g(z) = 2.72/2.78, accompanied by lower activity and drastically 
      inhibited intrinsic electron transfer from CuA to heme a. This intrinsic rate is 
      biphasic; the proportion that is slow is pH dependent, as is the relative 
      intensity of the two EPR signal components. At pH 8, the heme a EPR signal at 
      2.72 is most intense, and the electron transfer rate (CuA to heme a) is 10-130 
      s(-1), compared to wild-type at 90,000 s(-1). At pH 5.5, the signal at 2.78 is 
      intensified, and a biphasic rate is observed, 50% fast (approximately wild type) 
      and 50% slow (90 s(-1)). The data support the prediction that the 
      hydrogen-bonding partner of the histidine ligand of heme a is one determinant of 
      the EPR spectral difference between bovine and bacterial CcO. We further 
      demonstrate that the heme a redox potential can be dramatically altered by a 
      nearby carboxyl, whose protonation leads to a proton-coupled electron transfer 
      process.
FAU - Mills, Denise A
AU  - Mills DA
AD  - Department of Biochemistry and Molecular Biology, Michigan State University, East 
      Lansing, Michigan 48824, USA.
FAU - Xu, Shujuan
AU  - Xu S
FAU - Geren, Lois
AU  - Geren L
FAU - Hiser, Carrie
AU  - Hiser C
FAU - Qin, Ling
AU  - Qin L
FAU - Sharpe, Martyn A
AU  - Sharpe MA
FAU - McCracken, John
AU  - McCracken J
FAU - Durham, Bill
AU  - Durham B
FAU - Millett, Francis
AU  - Millett F
FAU - Ferguson-Miller, Shelagh
AU  - Ferguson-Miller S
LA  - eng
GR  - P20 RR015569/RR/NCRR NIH HHS/United States
GR  - F32 GM020488/GM/NIGMS NIH HHS/United States
GR  - GM26916/GM/NIGMS NIH HHS/United States
GR  - P20 RR15569/RR/NCRR NIH HHS/United States
GR  - GM20488/GM/NIGMS NIH HHS/United States
GR  - R01 GM020488/GM/NIGMS NIH HHS/United States
GR  - R01 GM054065/GM/NIGMS NIH HHS/United States
GR  - R37 GM026916-30/GM/NIGMS NIH HHS/United States
GR  - R37 GM026916/GM/NIGMS NIH HHS/United States
GR  - R01 GM026916/GM/NIGMS NIH HHS/United States
GR  - GM54065/GM/NIGMS NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, N.I.H., Extramural
DEP - 20081011
PL  - United States
TA  - Biochemistry
JT  - Biochemistry
JID - 0370623
RN  - 0 (DNA Primers)
RN  - 0 (Protons)
RN  - 0 (Recombinant Proteins)
RN  - 18535-39-2 (heme a)
RN  - 42VZT0U6YR (Heme)
RN  - 789U1901C5 (Copper)
RN  - EC 1.9.3.1 (Electron Transport Complex IV)
SB  - IM
MH  - Amino Acid Substitution
MH  - Animals
MH  - Base Sequence
MH  - Cattle
MH  - Copper/*chemistry
MH  - DNA Primers/genetics
MH  - Electron Spin Resonance Spectroscopy
MH  - Electron Transport
MH  - Electron Transport Complex IV/*chemistry/*genetics/metabolism
MH  - Heme/*analogs & derivatives/chemistry
MH  - Kinetics
MH  - Models, Molecular
MH  - Mutagenesis, Site-Directed
MH  - Protein Conformation
MH  - Protons
MH  - Recombinant Proteins/chemistry/genetics/metabolism
MH  - Rhodobacter sphaeroides/enzymology/genetics
MH  - Spectrophotometry
PMC - PMC2659347
MID - NIHMS82300
EDAT- 2008/10/14 09:00
MHDA- 2008/11/13 09:00
PMCR- 2009/11/04
CRDT- 2008/10/14 09:00
PHST- 2008/10/14 09:00 [pubmed]
PHST- 2008/11/13 09:00 [medline]
PHST- 2008/10/14 09:00 [entrez]
PHST- 2009/11/04 00:00 [pmc-release]
AID - 10.1021/bi801156s [doi]
PST - ppublish
SO  - Biochemistry. 2008 Nov 4;47(44):11499-509. doi: 10.1021/bi801156s. Epub 2008 Oct 
      11.