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PDBsum entry 2pw0
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Unknown function
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PDB id
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2pw0
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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 three-Dimensional crystal structure of the prpf protein of shewanella oneidensis complexed with trans-Aconitate: insights into its biological function.
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Authors
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G.S.Garvey,
C.J.Rocco,
J.C.Escalante-Semerena,
I.Rayment.
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Ref.
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Protein Sci, 2007,
16,
1274-1284.
[DOI no: ]
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PubMed id
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Abstract
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In bacteria, the dehydration of 2-methylcitrate to yield 2-methylaconitate in
the 2-methylcitric acid cycle is catalyzed by a cofactor-less (PrpD) enzyme or
by an aconitase-like (AcnD) enzyme. Bacteria that use AcnD also require the
function of the PrpF protein, whose function was previously unknown. To gain
insights into the function of PrpF, the three-dimensional crystal structure of
the PrpF protein from the bacterium Shewanella oneidensis was solved at 2.0 A
resolution. The protein fold of PrpF is strikingly similar to those of the
non-PLP-dependent diaminopimelate epimerase from Haemophilus influenzae, a
putative proline racemase from Brucella melitensis, and to a recently deposited
structure of a hypothetical protein from Pseudomonas aeruginosa. Results from in
vitro studies show that PrpF isomerizes trans-aconitate to cis-aconitate. It is
proposed that PrpF catalysis of the cis-trans isomerization proceeds through a
base-catalyzed proton abstraction coupled with a rotation about C2-C3 bond of
2-methylaconitate, and that residue Lys73 is critical for PrpF function. The
newly identified function of PrpF as a non-PLP-dependent isomerase, together
with the fact that PrpD-containing bacteria do not require PrpF, suggest that
the isomer of 2-methylaconitate that serves as a substrate of aconitase must
have the same stereochemistry as that synthesized by PrpD. From this, it follows
that the 2-methylaconitate isomer generated by AcnD is not a substrate of
aconitase, and that PrpF is required to generate the correct isomer. As a
consequence, the isomerase activity of PrpF may now be viewed as an integral
part of the 2-methylcitric acid cycle.
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Figure 1.
Figure 1. Schematic representation of the 2-methylcitric acid cycle with
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Figure 7.
Figure 7. Established mechanism for aconitate isomerase from P. putida
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The above figures are
reprinted
by permission from the Protein Society:
Protein Sci
(2007,
16,
1274-1284)
copyright 2007.
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