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PDBsum entry 2fkf
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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 reaction of phosphohexomutase from pseudomonas aeruginosa: structural insights into a simple processive enzyme.
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Authors
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C.Regni,
A.M.Schramm,
L.J.Beamer.
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Ref.
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J Biol Chem, 2006,
281,
15564-15571.
[DOI no: ]
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PubMed id
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Abstract
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The enzyme phosphomannomutase/phosphoglucomutase (PMM/PGM) from Pseudomonas
aeruginosa catalyzes the reversible conversion of 1-phospho to 6-phospho-sugars.
The reaction entails two phosphoryl transfers, with an intervening 180 degrees
reorientation of the reaction intermediate (e.g. glucose 1,6-bisphosphate)
during catalysis. Reorientation of the intermediate occurs without dissociation
from the active site of the enzyme and is, thus, a simple example of
processivity, as defined by multiple rounds of catalysis without release of
substrate. Structural characterization of two PMM/PGM-intermediate complexes
with glucose 1,6-bisphosphate provides new insights into the reaction catalyzed
by the enzyme, including the reorientation of the intermediate. Kinetic analyses
of site-directed mutants prompted by the structural studies reveal active site
residues critical for maintaining association with glucose 1,6-bisphosphate
during its unique dynamic reorientation in the active site of PMM/PGM.
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Figure 2.
FIGURE 2. The final 2 F[o] – F[c] maps (blue, contoured
at 1. 0  ) for G16P in the
dephospho-PMM/PGM·G16P complex (a) and
phospho-PMM/PGM·G16P complex (b). Electron density for
Arg-15 and Arg-20 is also shown for this complex.
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Figure 3.
FIGURE 3. a, superposition of the protein backbones for
apo-PMM/PGM (Apo) and its complexes with G16P. DP,
dephospho-PMM/PGM; P, phospho-PMM/PGM. Domains 1–4 are shown
in green, yellow, red, and blue, respectively. G16P as bound to
phosphoenzyme is shown in magenta and to dephosphoenzyme is
shown in cyan. b, a close-up view of G16P in the active site of
the two PMM/PGM-intermediate complexes showing their different
relative binding positions. The protein backbone is shown in
solid (dephosphoenzyme) and semitransparent (phosphoenzyme).
Shown are hydrogen bonds between G16P and dephospho-PMM/PGM (c)
and phospho-PMM/PGM (d). Protein residues that contact the
intermediate are shown as sticks; water molecules are shown as
blue spheres.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2006,
281,
15564-15571)
copyright 2006.
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