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PDBsum entry 3fcc
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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 structure of bacillus cereus d-Alanyl carrier protein ligase (dlta) in complex with ATP.
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Authors
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K.T.Osman,
L.Du,
Y.He,
Y.Luo.
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Ref.
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J Mol Biol, 2009,
388,
345-355.
[DOI no: ]
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PubMed id
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Abstract
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D-alanylation of lipoteichoic acids modulates the surface charge and ligand
binding of the Gram-positive cell wall. Disruption of the bacterial dlt operon
involved in teichoic acid alanylation, as well as inhibition of the DltA
(D-alanyl carrier protein ligase) protein, has been shown to render the
bacterium more susceptible to conventional antibiotics and host defense
responses. The DltA catalyzes the adenylation and thiolation reactions of
d-alanine. This enzyme belongs to a superfamily of AMP-forming domains such as
the ubiquitous acetyl-coenzyme A synthetase. We have determined the
1.9-A-resolution crystal structure of a DltA protein from Bacillus cereus in
complex with ATP. This structure sheds light on the geometry of the bound ATP.
The invariant catalytic residue Lys492 appears to be mobile, suggesting a
molecular mechanism of catalysis for this superfamily of enzymes. Specific roles
are also revealed for two other invariant residues: the divalent
cation-stabilizing Glu298 and the beta-phosphate-interacting Arg397. Mutant
proteins with a glutamine substitution at position 298 or 397 are inactive.
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Figure 3.
Fig. 3. Structural comparison of DltA and human medium-chain
ACS in stereo. The superimposed ATP-binding pockets are shown.
The BcDltA model is shown as in Fig. 2c. The counterparts in the
human ACS are shown in gray.
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Figure 5.
Fig. 5. Adenylation model in stereo. The model was based on
the BcDltA/ATP structure and the BcDltA/adenylate structure. The
orientation and coloring scheme are similar to those in Fig. 2b.
The  epsilon
-amino group of the mobile Lys492 residue escorts the electron
transfer from the nucleophilic d-alanyl carboxylate group via a
pentavalent transition state to the leaving pyrophosphate.
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The above figures are
reprinted
by permission from Elsevier:
J Mol Biol
(2009,
388,
345-355)
copyright 2009.
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