Advanced

Transmembrane topology and axial ligands to hemes in the cytochrome b subunit of Bacillus subtilis succinate:menaquinone reductase

Hägerhäll, Cecilia LU ; Fridén, H; Aasa, Roland and Hederstedt, Lars LU (1995) In Biochemistry 34(35). p.11080-11089
Abstract
The membrane-anchoring subunit of Bacillus subtilis succinate:menaquinone reductase is a protein of 202 residues containing two protoheme IX groups with bis-histidine axial ligation. Residues Kis13, His28, His70, His113, and His155 are the possible heme ligands. The transmembrane topology of this cytochrome was analyzed using fusions to alkaline phosphatase. The results support a proposed model with five transmembrane polypeptide segments and the N-terminus exposed to the cytoplasm. Mutant B. subtilis cytochromes containing a His13 --> Tyr, a His28 --> Tyr, and a His113 --> Tyr mutation, respectively, were produced in Escherichia coli, partially purified, and analyzed. In addition, succinate: menaquinone reductase containing the... (More)
The membrane-anchoring subunit of Bacillus subtilis succinate:menaquinone reductase is a protein of 202 residues containing two protoheme IX groups with bis-histidine axial ligation. Residues Kis13, His28, His70, His113, and His155 are the possible heme ligands. The transmembrane topology of this cytochrome was analyzed using fusions to alkaline phosphatase. The results support a proposed model with five transmembrane polypeptide segments and the N-terminus exposed to the cytoplasm. Mutant B. subtilis cytochromes containing a His13 --> Tyr, a His28 --> Tyr, and a His113 --> Tyr mutation, respectively, were produced in Escherichia coli, partially purified, and analyzed. In addition, succinate: menaquinone reductase containing the His13 --> Tyr mutation in the anchor subunit was overproduced in B. subtilis, purified, and characterized. The data demonstrate that His13 is not an axial heme ligand. Thermodynamic and spectroscopic properties of the cytochrome are, however, affected by the His13 --> mutation; compared to wild type, the redox potentials of both hemes are negatively shifted and the g(max) signal in the EPR spectrum of the high-potential heme is shifted from 3.68 to 3.50. From the combined results we conclude that His28 and His113 function as axial ligands to the low-potential heme, which is located in the membrane near the outer surface of the cytoplasmic membrane. Residues His70 and His155 ligate the high-potential heme, which is positioned close to His13 in the protein, near the inner surface of the membrane. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biochemistry
volume
34
issue
35
pages
11080 - 11089
publisher
The American Chemical Society
external identifiers
  • scopus:0029103120
ISSN
0006-2960
DOI
10.1021/bi00035a013
language
English
LU publication?
yes
id
34cfd2f9-9614-4b29-a732-befb3c7e31aa
date added to LUP
2017-07-18 10:09:11
date last changed
2017-09-10 05:21:59
@article{34cfd2f9-9614-4b29-a732-befb3c7e31aa,
  abstract     = {The membrane-anchoring subunit of Bacillus subtilis succinate:menaquinone reductase is a protein of 202 residues containing two protoheme IX groups with bis-histidine axial ligation. Residues Kis13, His28, His70, His113, and His155 are the possible heme ligands. The transmembrane topology of this cytochrome was analyzed using fusions to alkaline phosphatase. The results support a proposed model with five transmembrane polypeptide segments and the N-terminus exposed to the cytoplasm. Mutant B. subtilis cytochromes containing a His13 --> Tyr, a His28 --> Tyr, and a His113 --> Tyr mutation, respectively, were produced in Escherichia coli, partially purified, and analyzed. In addition, succinate: menaquinone reductase containing the His13 --> Tyr mutation in the anchor subunit was overproduced in B. subtilis, purified, and characterized. The data demonstrate that His13 is not an axial heme ligand. Thermodynamic and spectroscopic properties of the cytochrome are, however, affected by the His13 --> mutation; compared to wild type, the redox potentials of both hemes are negatively shifted and the g(max) signal in the EPR spectrum of the high-potential heme is shifted from 3.68 to 3.50. From the combined results we conclude that His28 and His113 function as axial ligands to the low-potential heme, which is located in the membrane near the outer surface of the cytoplasmic membrane. Residues His70 and His155 ligate the high-potential heme, which is positioned close to His13 in the protein, near the inner surface of the membrane.},
  author       = {Hägerhäll, Cecilia and Fridén, H and Aasa, Roland and Hederstedt, Lars},
  issn         = {0006-2960},
  language     = {eng},
  number       = {35},
  pages        = {11080--11089},
  publisher    = {The American Chemical Society},
  series       = {Biochemistry},
  title        = {Transmembrane topology and axial ligands to hemes in the cytochrome b subunit of <em>Bacillus subtilis</em> succinate:menaquinone reductase},
  url          = {http://dx.doi.org/10.1021/bi00035a013},
  volume       = {34},
  year         = {1995},
}