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PDBsum entry 2h9c
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References listed in PDB file
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Key reference
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Title
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Two crystal structures of the isochorismate pyruvate lyase from pseudomonas aeruginosa.
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Authors
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J.Zaitseva,
J.Lu,
K.L.Olechoski,
A.L.Lamb.
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Ref.
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J Biol Chem, 2006,
281,
33441-33449.
[DOI no: ]
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PubMed id
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Abstract
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Enzymatic systems that exploit pericyclic reaction mechanisms are rare. A recent
addition to this class is the enzyme PchB, an 11.4-kDa isochorismate pyruvate
lyase from Pseudomonas aeruginosa. The apo and pyruvate-bound structures of PchB
reveal that the enzyme is a structural homologue of chorismate mutases in the
AroQalpha class despite low sequence identity (20%). The enzyme is an
intertwined dimer of three helices with connecting loops, and amino acids from
each monomer participate in each of two active sites. The apo structure (2.35 A
resolution) has one dimer per asymmetric unit with nitrate bound in an open
active site. The loop between the first and second helices is disordered,
providing a gateway for substrate entry and product exit. The pyruvate-bound
structure (1.95 A resolution) has two dimers per asymmetric unit. One has two
open active sites like the apo structure, and the other has two closed active
sites with the loop between the first and second helices ordered for catalysis.
Determining the structure of PchB is part of a larger effort to elucidate
protein structures involved in siderophore biosynthesis, as these enzymes are
crucial for bacterial iron uptake and virulence and have been identified as
antimicrobial drug targets.
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Figure 5.
FIGURE 5. Stereoviews of the active sites of apo PchB (a)
with the closed pyruvate-bound PchB (b) and EcCM (c). The colors
used are as described in Fig. 2. The amino acid legends in panel
b indicate monomer name, residue number, and one-letter amino
acid code and are in capital letters if they are conserved
between PchB and EcCM and lowercase if they are not.
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Figure 6.
FIGURE 6. Two-dimensional schematic representation of the
protein-ligand contacts in the closed, pyruvate-bound structure
(a) and the wrong-ligand crystallographic refinement model
containing salicylate and pyruvate (b). The amino acid side
chains are shown as sticks and labeled with the three-letter
amino acid code, amino acid number, and monomer name. The
pyruvate and salicylate molecules are depicted as ball-and-stick
and are labeled "Pyr 1," "Pyr 2," and "SalI" with a monomer name
of (E). The carbon atoms are black, and the oxygen atoms are
white. This figure was generated with LIGPLOT (31).
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2006,
281,
33441-33449)
copyright 2006.
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