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PDBsum entry 1n2a
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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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Conserved structural elements in glutathione transferase homologues encoded in the genome of escherichia coli.
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Authors
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C.L.Rife,
J.F.Parsons,
G.Xiao,
G.L.Gilliland,
R.N.Armstrong.
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Ref.
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Proteins, 2003,
53,
777-782.
[DOI no: ]
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PubMed id
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Abstract
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Multiple sequence alignments of the eight glutathione (GSH) transferase
homologues encoded in the genome of Escherichia coli were used to define a
consensus sequence for the proteins. The consensus sequence was analyzed in the
context of the three-dimensional structure of the gst gene product (EGST)
obtained from two different crystal forms of the enzyme. The enzyme consists of
two domains. The N-terminal region (domain I) has a thioredoxin-like
alpha/beta-fold, while the C-terminal domain (domain II) is all alpha-helical.
The majority of the consensus residues (12/17) reside in the N-terminal domain.
Fifteen of the 17 residues are involved in hydrophobic core interactions, turns,
or electrostatic interactions between the two domains. The results suggest that
all of the homologues retain a well-defined group of structural elements both in
and between the N-terminal alpha/beta domain and the C-terminal domain. The
conservation of two key residues for the recognition motif for the
gamma-glutamyl-portion of GSH indicates that the homologues may interact with
GSH or GSH analogues such as glutathionylspermidine or alpha-amino acids. The
genome context of two of the homologues forms the basis for a hypothesis that
the b2989 and yibF gene products are involved in glutathionylspermidine and
selenium biochemistry, respectively.
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Figure 2.
Figure 2. Distribution of consensus residues in the gst gene
product from Escherichia coli. Ribbon diagram of monomer A of
EGST illustrating the distribution of conserved residues amongst
the homologues. Domains I and II are illustrated in orange and
light blue, respectively. The side chains of the 17 consensus
residues are highlighted in van der Waals representations.
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Figure 5.
Figure 5. View of the  -glutamyl
binding motif at the turn between  -strand-4
and helix-2 in the N-terminal domain. The carboxylate of E65 and
the main-chain N-H of G66 are within hydrogen bonding distance
of the  -amino
and -carboxyl
groups of the glutamyl residues of GSO [LaTeX2gif.pl?%5Cdocumentclass%7Bminimal%7D%5Cbegin%7Bdocument%7D%5C%28%5E%7B-%7D_%7B3%7D%5C%29%5Cend%7Bdocument%7D]
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The above figures are
reprinted
by permission from John Wiley & Sons, Inc.:
Proteins
(2003,
53,
777-782)
copyright 2003.
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