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PDBsum entry 1k4j
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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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Structural basis and specificity of acyl-Homoserine lactone signal production in bacterial quorum sensing.
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Authors
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W.T.Watson,
T.D.Minogue,
D.L.Val,
S.B.Von bodman,
M.E.Churchill.
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Ref.
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Mol Cell, 2002,
9,
685-694.
[DOI no: ]
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PubMed id
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Abstract
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Synthesis and detection of acyl-homoserine lactones (AHLs) enables many
gram-negative bacteria to engage in quorum sensing, an intercellular signaling
mechanism that activates differentiation to virulent and biofilm lifestyles. The
AHL synthases catalyze acylation of S-adenosyl-L-methionine by acyl-acyl carrier
protein and lactonization of the methionine moiety to give AHLs. The crystal
structure of the AHL synthase, EsaI, determined at 1.8 A resolution, reveals a
remarkable structural similarity to the N-acetyltransferases and defines a
common phosphopantetheine binding fold as the catalytic core. Critical residues
responsible for catalysis and acyl chain specificity have been identified from a
modeled substrate complex and verified through functional analysis in vivo. A
mechanism for the N-acylation of S-adenosyl-L-methionine by 3-oxo-hexanoyl-acyl
carrier protein is proposed.
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Figure 2.
Figure 2. Sequence and Structural Alignment of Selected AHL
Synthases and GNATsThe sequence and topology of the AHL synthase
family is compared to the GCN5-related N-acetyltransferases. The
gray shaded regions are conserved sequence blocks within each
family that constitute the enzyme's “sequence signature.”
Residues are colored red to indicate acidic or hydrophilic, blue
for basic, and orange for other. Shaded residues are absolutely
conserved, and the boxed residues are homologous within each
family. Residues that comprise the core “phosphopantetheine
binding fold” were identified by LSQMAN using a 2.0 Å
cutoff and are indicated by black bars above the segments. The
Tetrahymena GCN5 residues that contact the pantetheine or acetyl
portion of the acetyl-CoA are indicated by “p” or “a,”
respectively.
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Figure 4.
Figure 4. Proposed Mechanism of Acyl Transfer(A) The
stereodiagram of acyl-phosphopantetheine modeled into the EsaI
active-site cavity viewed as in Figure 2A. The electrostatic
surface, generated using GRASP (Nicholls et al., 1993) and
Photoshop (Adobe), is colored red, white, and blue to indicate
negatively charged, neutral, or positively charged regions of
the surface, respectively. The individual atoms in the modeled
phosphopantetheine are colored according to atom type.(B) The
acylation cleft of EsaI and relevant residues are shown in
gray, the modeled phosphopanteteine is shown in cyan, and the
well-ordered water molecules observed in the native structure
that lie along β4 are shown as red spheres.(C) The proposed
N-acylation reaction is catalyzed via nucleophilic attack on the
1-carbonyl of acyl-ACP by the free amine electrons of SAM after
proton abstraction by a water molecule stabilized by Glu97 or
Ser99.
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The above figures are
reprinted
by permission from Cell Press:
Mol Cell
(2002,
9,
685-694)
copyright 2002.
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Secondary reference #1
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Title
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Crystallization and rhenium mad phasing of the acyl-Homoserinelactone synthase esai.
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Authors
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W.T.Watson,
F.V.Murphy,
T.A.Gould,
P.Jambeck,
D.L.Val,
J.E.Cronan,
S.Beck von bodman,
M.E.Churchill.
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Ref.
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Acta Crystallogr D Biol Crystallogr, 2001,
57,
1945-1949.
[DOI no: ]
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PubMed id
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Figure 2.
Figure 2 Perrhenate binding sites. (a) A stereoview of a
simulated-annealing composite omit map (2F[o] - F[c]) contoured
at 1  illustrates
the environment of four rhenium ions in the protein. The figure
was generated using SETOR (Evans, 1993[Evans, S. (1993). J. Mol.
Graph. 11, 134-138.]) and Photoshop (Adobe). (b) A GRASP surface
representation of EsaI in stereoview colored according to the
calculated electrostatic potential with the most electronegative
regions colored in red, and the most electropositive in blue
(Nicholls et al., 1993[Nicholls, A., Bharadwaj, R. & Honig, B.
(1993). Biophys. J. 64, A166.]). The five positively identified
perrhanate ions, based on their anomalous signal by SOLVE, are
shown as green spheres.
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The above figure is
reproduced from the cited reference
with permission from the IUCr
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