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Heme a synthase in bacteria depends on one pair of cysteinyls for activity.

Lewin, Anna LU and Hederstedt, Lars LU (2016) In Biochimica et Biophysica Acta 1857(2). p.160-168
Abstract
Heme A is a prosthetic group unique for cytochrome a-type respiratory oxidases in mammals, plants and many microorganisms. The poorly understood integral membrane protein heme A synthase catalyzes the synthesis of heme A from heme O. In bacteria, but not in mitochondria, this enzyme contains one or two pairs of cysteine residues that are present in predicted hydrophilic polypeptide loops on the extracytoplasmic side of the membrane. We used heme A synthase from the eubacterium Bacillus subtilis and the hyperthermophilic archeon Aeropyrum pernix to investigate the functional role of these cysteine residues. Results with B. subtilis amino acid substituted proteins indicated the pair of cysteine residues in the loop connecting transmembrane... (More)
Heme A is a prosthetic group unique for cytochrome a-type respiratory oxidases in mammals, plants and many microorganisms. The poorly understood integral membrane protein heme A synthase catalyzes the synthesis of heme A from heme O. In bacteria, but not in mitochondria, this enzyme contains one or two pairs of cysteine residues that are present in predicted hydrophilic polypeptide loops on the extracytoplasmic side of the membrane. We used heme A synthase from the eubacterium Bacillus subtilis and the hyperthermophilic archeon Aeropyrum pernix to investigate the functional role of these cysteine residues. Results with B. subtilis amino acid substituted proteins indicated the pair of cysteine residues in the loop connecting transmembrane segments I and II as being essential for catalysis but not required for binding of the enzyme substrate, heme O. Experiments with isolated A. pernix and B. subtilis heme A synthase demonstrated that a disulfide bond can form between the cysteine residues in the same loop and also between loops showing close proximity of the two loops in the folded enzyme protein. Based on the findings we propose a classification scheme for the four discrete types of heme A synthase found so far in different organisms and propose that essential cysteinyls mediate transfer of reducing equivalents required for the oxygen-dependent catalysis of heme A synthesis from heme O. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Heme biosynthesis, Cytochrome a, Bacillus subtilis, Aeropyrum pernix, CtaA, COX15, Protein disulfide
in
Biochimica et Biophysica Acta
volume
1857
issue
2
pages
160 - 168
publisher
Elsevier
external identifiers
  • pmid:26592143
  • wos:000368204400004
  • scopus:84950000434
ISSN
0006-3002
DOI
10.1016/j.bbabio.2015.11.008
language
English
LU publication?
yes
id
8241b1fb-0286-4f82-b588-8fc56c60703a (old id 8234915)
date added to LUP
2015-12-08 13:18:52
date last changed
2017-08-09 10:03:53
@article{8241b1fb-0286-4f82-b588-8fc56c60703a,
  abstract     = {Heme A is a prosthetic group unique for cytochrome a-type respiratory oxidases in mammals, plants and many microorganisms. The poorly understood integral membrane protein heme A synthase catalyzes the synthesis of heme A from heme O. In bacteria, but not in mitochondria, this enzyme contains one or two pairs of cysteine residues that are present in predicted hydrophilic polypeptide loops on the extracytoplasmic side of the membrane. We used heme A synthase from the eubacterium Bacillus subtilis and the hyperthermophilic archeon Aeropyrum pernix to investigate the functional role of these cysteine residues. Results with B. subtilis amino acid substituted proteins indicated the pair of cysteine residues in the loop connecting transmembrane segments I and II as being essential for catalysis but not required for binding of the enzyme substrate, heme O. Experiments with isolated A. pernix and B. subtilis heme A synthase demonstrated that a disulfide bond can form between the cysteine residues in the same loop and also between loops showing close proximity of the two loops in the folded enzyme protein. Based on the findings we propose a classification scheme for the four discrete types of heme A synthase found so far in different organisms and propose that essential cysteinyls mediate transfer of reducing equivalents required for the oxygen-dependent catalysis of heme A synthesis from heme O.},
  author       = {Lewin, Anna and Hederstedt, Lars},
  issn         = {0006-3002},
  keyword      = {Heme biosynthesis,Cytochrome a,Bacillus subtilis,Aeropyrum pernix,CtaA,COX15,Protein disulfide},
  language     = {eng},
  number       = {2},
  pages        = {160--168},
  publisher    = {Elsevier},
  series       = {Biochimica et Biophysica Acta},
  title        = {Heme a synthase in bacteria depends on one pair of cysteinyls for activity.},
  url          = {http://dx.doi.org/10.1016/j.bbabio.2015.11.008},
  volume       = {1857},
  year         = {2016},
}