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PDBsum entry 1dw2
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Oxygen storage/transport
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PDB id
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1dw2
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Crystal structures of an oxygen-Binding cytochrome c from rhodobacter sphaeroides.
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Authors
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D.Leys,
K.Backers,
T.E.Meyer,
W.R.Hagen,
M.A.Cusanovich,
J.J.Van beeumen.
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Ref.
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J Biol Chem, 2000,
275,
16050-16056.
[DOI no: ]
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PubMed id
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Abstract
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The photosynthetic bacterium Rhodobacter sphaeroides produces a heme protein
(SHP), which is an unusual c-type cytochrome capable of transiently binding
oxygen during autooxidation. Similar proteins have not only been observed in
other photosynthetic bacteria but also in the obligate methylotroph
Methylophilus methylotrophus and the metal reducing bacterium Shewanella
putrefaciens. A three-dimensional structure of SHP was derived using the
multiple isomorphous replacement phasing method. Besides a model for the
oxidized state (to 1.82 A resolution), models for the reduced state (2.1 A
resolution), the oxidized molecule liganded with cyanide (1. 90 A resolution),
and the reduced molecule liganded with nitric oxide (2.20 A resolution) could be
derived. The SHP structure represents a new variation of the class I cytochrome
c fold. The oxidized state reveals a novel sixth heme ligand, Asn(88), which
moves away from the iron upon reduction or when small molecules bind. The distal
side of the heme has a striking resemblance to other heme proteins that bind
gaseous compounds. In SHP the liberated amide group of Asn(88) stabilizes
solvent-shielded ligands through a hydrogen bond.
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Figure 1.
Fig. 1. . Alignment of the SHP from S. putrefaciens
(PHP), cytochrome c" of M. methylotrophus (16) (MHP), and SHP
from R. sphaeroides (12) (SHP). Heme ligands are colored red,
residues implicated in lining the distal heme pocket are blue,
the sixth heme ligand is green, and the two cysteines linked in
a disulfide bridge are yellow. Residues conserved in all three
sequences have been boxed.
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Figure 3.
Fig. 3. Ribbon diagrams of the oxidized SHP structure.
Heme is represented in fine bonds, and His47, Asn88, Cys89, and
Cys91 have been depicted by ball and sticks. This figure has
been generated using the programs MOLSCRIPT (41) and RASTER3D
(42).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2000,
275,
16050-16056)
copyright 2000.
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