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PDBsum entry 1mn2
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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 substrate binding site mutants of manganese peroxidase.
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Authors
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M.Sundaramoorthy,
K.Kishi,
M.H.Gold,
T.L.Poulos.
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Ref.
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J Biol Chem, 1997,
272,
17574-17580.
[DOI no: ]
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PubMed id
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Abstract
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Manganese peroxidase (MnP), an extracellular heme enzyme from the
lignin-degrading basidiomycetous fungus, Phanerochaete chrysosporium, catalyzes
the oxidation of MnII to MnIII. The latter, acting as a diffusible redox
mediator, is capable of oxidizing a variety of lignin model compounds. The
proposed MnII binding site of MnP consists of a heme propionate, three acidic
ligands (Glu-35, Glu-39, and Asp-179), and two water molecules. Using
crystallographic methods, this binding site was probed by altering the amount of
MnII bound to the protein. Crystals grown in the absence of MnII, or in the
presence of EDTA, exhibited diminished electron density at this site. Crystals
grown in excess MnII exhibited increased electron density at the proposed
binding site but nowhere else in the protein. This suggests that there is only
one major MnII binding site in MnP. Crystal structures of a single mutant
(D179N) and a double mutant (E35Q,D179N) at this site were determined. The
mutant structures lack a cation at the MnII binding site. The structure of the
MnII binding site is altered significantly in both mutants, resulting in
increased access to the solvent and substrate.
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Figure 4.
Fig. 4. Stereo representations of refined structures and
interactions around the MnII binding site in the D179N single
mutant (A) and in the E35Q,D179N double mutant (B). In
E35Q,D179N, Gln-35 is modeled in two conformations, and Wat-653
is present only in the open conformation of Gln-35. In D179N
Wat-653 is fully occupied, and the extra space^ left by the
movement of Glu-35 is occupied by Wat-441. Wat-653^ forms
hydrogen bond interaction with the heme propionate, Glu-39,
Asn-179, and a solvent (Wat-441 in the single mutant and
Wat-650^ in the double mutant).
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Figure 5.
Fig. 5. Edge-on view of van der Waals surface representations
of native MnP (A), the D179N single mutant, down the MnII
binding site (B), and the E35Q,D179N double mutant (C). The^
color coding is as follows: heme, red; side chain ligands,
green; MnII, yellow; and mutated side chains, purple.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(1997,
272,
17574-17580)
copyright 1997.
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Secondary reference #1
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Title
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The crystal structure of manganese peroxidase from phanerochaete chrysosporium at 2.06-A resolution.
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Authors
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M.Sundaramoorthy,
K.Kishi,
M.H.Gold,
T.L.Poulos.
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Ref.
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J Biol Chem, 1994,
269,
32759-32767.
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PubMed id
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