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PDBsum entry 2nsf
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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 structures and site-Directed mutagenesis of a mycothiol-Dependent enzyme reveal a novel folding and molecular basis for mycothiol-Mediated maleylpyruvate isomerization.
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Authors
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R.Wang,
Y.J.Yin,
F.Wang,
M.Li,
J.Feng,
H.M.Zhang,
J.P.Zhang,
S.J.Liu,
W.R.Chang.
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Ref.
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J Biol Chem, 2007,
282,
16288-15294.
[DOI no: ]
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PubMed id
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Abstract
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Mycothiol (MSH) is the major low molecular mass thiols in many Gram-positive
bacteria such as Mycobacterium tuberculosis and Corynebacterium glutamicum. The
physiological roles of MSH are believed to be equivalent to those of GSH in
Gram-negative bacteria, but current knowledge of MSH is limited to
detoxification of alkalating chemicals and protection from host cell
defense/killing systems. Recently, an MSH-dependent maleylpyruvate isomerase
(MDMPI) was discovered from C. glutamicum, and this isomerase represents one
example of many putative MSH-dependent enzymes that take MSH as cofactor. In
this report, fourteen mutants of MDMPI were generated. The wild type and mutant
(H52A) MDMPIs were crystallized and their structures were solved at 1.75 and
2.05A resolution, respectively. The crystal structures reveal that this enzyme
contains a divalent metal-binding domain and a C-terminal domain possessing a
novel folding pattern (alphabetaalphabetabetaalpha fold). The divalent
metal-binding site is composed of residues His(52), Glu(144), and His(148) and
is located at the bottom of a surface pocket. Combining the structural and
site-directed mutagenesis studies, it is proposed that this surface pocket
including the metal ion and MSH moiety formed the putative catalytic center.
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Figure 4.
FIGURE 4. The side chain of Arg^222 (NH1) at the C-terminal
domain interacts with Asp^151 (OD2) of the N-terminal domain
through a salt bridge. The N-terminal domain is shown in yellow,
C-terminal domain in cyan, and interdomain coil in gray. Asp^151
and Arg^222 are represented in stick model (carbon atoms are
colored the same as the domain they locate at) and the metal ion
by a sphere (gray). Salt bridge is shown by dashed line. The
figure was created by PyMol.
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Figure 6.
FIGURE 6. The stereo view of the conformation differences
in the putative active pocket between the wild type and the
mutant (H52A) MDMPI. Mutant H52A is shown in purple and native
MDMPI in green. Conformation differences were found at the side
chains of Arg^82 and Trp^44. In H52A the metal ion was missing
and a glycerol occupied the position of the metal ion, and the
location of SO^2–[4] also changed. Furthermore, there is no
obvious conformation changes observed, when compared with that
of the wild type. The image was created by PyMol.
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The above figures are
reprinted
by permission from the ASBMB:
J Biol Chem
(2007,
282,
16288-15294)
copyright 2007.
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