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PDBsum entry 1gv3
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Manganese superoxide dismutase
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PDB id
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1gv3
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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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The 2.0a resolution structure of the catalytic portion of a cyanobacterial membrane-Bound manganese superoxide dismutase.
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Authors
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W.Atzenhofer,
G.Regelsberger,
U.Jacob,
G.Peschek,
P.Furtmüller,
R.Huber,
C.Obinger.
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Ref.
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J Mol Biol, 2002,
321,
479-489.
[DOI no: ]
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PubMed id
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Abstract
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Cyanobacteria are shown to be unique in containing membrane-bound manganese
superoxide dismutases (MnSOD). They are homodimeric type 2 membrane proteins
that protect this phototrophic organism against oxidative stress. We have
determined, for the first time, the 2.0A resolution structure of the catalytic
portion of the MnSOD from the filamentous cyanobacterium Anabaena PCC 7120.
Within each subunit, both the N-terminal helical hairpin (His94 and His145) and
the C-terminal alpha/beta domain (His232 and Asp228) contribute ligands to the
catalytic manganese site. Together with a water or hydroxide ion (OH(x)) a
five-coordinated trigonal bipyramidal geometry is formed, with OH(x) and His90
forming the axial ligands and manganese shifted out of the equatorial plane in
the direction of OH(x). The ligands including OH(x) are tightly constrained by
hydrogen bonding with surrounding residues either from the same monomer (Tyr98,
Asn144, Trp194, Gln213, Val229, Trp230) or from the neighbouring subunit
(Glu231, Tyr235). This underlines the important role of the symmetric dimeric
structure of MnSODs in contributing elements to both the active site and the
substrate funnel. The Mn cdots, three dots, centered Mn distance (18.4A) is
bridged by the hydrogen-bonded His232 of one monomer with Glu231 of the other
monomer. A detailed discussion of the structure, a comparison with known
structures of soluble MnSODs as well as a model of the cyanobacterial
membrane-bound MnSOD is presented.
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Figure 6.
Figure 6. Overlay of tube representations of T.
thermophilus (blue) and Anabaena PCC 7120 MnSOD dimers (red).
The manganese ion is drawn as a yellow sphere. Figure 6, Figure
7 and Figure 8 were produced using MOLSCRIPT. [39 and 40]
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Figure 8.
Figure 8. Diagram of the symmetric dimer interface.
Residues from each subunit are shown in either orange or yellow.
Ribbons are rendered in light blue or brown. Direct interactions
between amino acid residues of opposing chains are shown as
broken green lines labeled by the corresponding bond length in
Å.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2002,
321,
479-489)
copyright 2002.
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