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The distal heme center in Bacillus subtilis succinate:menaquinone reductase is crucial for electron transfer to menaquinone

Matsson, Mikael LU ; Tolstoy, Daria; Aasa, Roland and Hederstedt, Lars LU (2000) In Biochemistry 39. p.8617-8624
Abstract
Succinate:quinone reductases are membrane-bound enzymes that catalyze electron transfer from succinate to quinone. Some enzymes in vivo reduce ubiquinone (exergonic reaction) whereas others reduce menaquinone (endergonic reaction). The succinate:menaquinone reductases all contain two heme groups in the membrane anchor of the enzyme: a proximal heme (heme b(P)) located close to the negative side of the membrane and a distal heme (heme b(D)) located close to the positive side of the membrane. Heme b(D) is a distinctive feature of the succinate:menaquinone reductases, but the role of this heme in electron transfer to quinone has not previously been analyzed. His28 and His113 are the axial ligands to heme b(D) in Bacillus subtilis... (More)
Succinate:quinone reductases are membrane-bound enzymes that catalyze electron transfer from succinate to quinone. Some enzymes in vivo reduce ubiquinone (exergonic reaction) whereas others reduce menaquinone (endergonic reaction). The succinate:menaquinone reductases all contain two heme groups in the membrane anchor of the enzyme: a proximal heme (heme b(P)) located close to the negative side of the membrane and a distal heme (heme b(D)) located close to the positive side of the membrane. Heme b(D) is a distinctive feature of the succinate:menaquinone reductases, but the role of this heme in electron transfer to quinone has not previously been analyzed. His28 and His113 are the axial ligands to heme b(D) in Bacillus subtilis succinate:menaquinone reductase. We have individually replaced these His residues with Leu and Met, respectively, resulting in assembled membrane- bound enzymes. The H28L mutant enzyme lacks succinate:quinone reductase activity probably due to a defective quinone binding site. The H113M mutant enzyme contains heme b(D) with raised midpoint potential and is impaired in electron transfer to menaquinone. Our combined experimental data show that the heme b(D) center, into which we include a quinone binding site, is crucial for succinate:menaquinone reductase activity. The results support a model in which menaquinone is reduced on the positive side of the membrane and the transmembrane electrochemical potential provides driving force for electron transfer from succinate via heme b(P) and heme b(D) to menaquinone. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
39
pages
8617 - 8624
publisher
The American Chemical Society
external identifiers
  • scopus:0034713845
ISSN
0006-2960
DOI
10.1021/bi000271m
language
English
LU publication?
yes
id
456ad91a-99af-41f1-a2aa-0bc95ef529e3
date added to LUP
2017-07-17 11:59:37
date last changed
2017-08-27 06:44:46
@article{456ad91a-99af-41f1-a2aa-0bc95ef529e3,
  abstract     = {Succinate:quinone reductases are membrane-bound enzymes that catalyze electron transfer from succinate to quinone. Some enzymes in vivo reduce ubiquinone (exergonic reaction) whereas others reduce menaquinone (endergonic reaction). The succinate:menaquinone reductases all contain two heme groups in the membrane anchor of the enzyme: a proximal heme (heme b(P)) located close to the negative side of the membrane and a distal heme (heme b(D)) located close to the positive side of the membrane. Heme b(D) is a distinctive feature of the succinate:menaquinone reductases, but the role of this heme in electron transfer to quinone has not previously been analyzed. His28 and His113 are the axial ligands to heme b(D) in Bacillus subtilis succinate:menaquinone reductase. We have individually replaced these His residues with Leu and Met, respectively, resulting in assembled membrane- bound enzymes. The H28L mutant enzyme lacks succinate:quinone reductase activity probably due to a defective quinone binding site. The H113M mutant enzyme contains heme b(D) with raised midpoint potential and is impaired in electron transfer to menaquinone. Our combined experimental data show that the heme b(D) center, into which we include a quinone binding site, is crucial for succinate:menaquinone reductase activity. The results support a model in which menaquinone is reduced on the positive side of the membrane and the transmembrane electrochemical potential provides driving force for electron transfer from succinate via heme b(P) and heme b(D) to menaquinone.},
  author       = {Matsson, Mikael and Tolstoy, Daria and Aasa, Roland and Hederstedt, Lars},
  issn         = {0006-2960},
  language     = {eng},
  pages        = {8617--8624},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {The distal heme center in <em>Bacillus subtilis</em> succinate:menaquinone reductase is crucial for electron transfer to menaquinone},
  url          = {http://dx.doi.org/10.1021/bi000271m},
  volume       = {39},
  year         = {2000},
}