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PDBsum entry 1rtc
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References listed in PDB file
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Key reference
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Title
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Structure of recombinant ricin a chain at 2.3 a.
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Authors
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D.Mlsna,
A.F.Monzingo,
B.J.Katzin,
S.Ernst,
J.D.Robertus.
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Ref.
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Protein Sci, 1993,
2,
429-435.
[DOI no: ]
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PubMed id
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Abstract
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The plant cytotoxin ricin is a heterodimer with a cell surface binding (B) chain
and an enzymatically active A chain (RTA) known to act as a specific
N-glycosidase. RTA must be separated from B chain to attack rRNA. The X-ray
structure of ricin has been solved recently; here we report the structure of the
isolated A chain expressed from a clone in Escherichia coli. This structure of
wild-type rRTA has and will continue to serve as the parent compound for
difference Fouriers used to assess the structure of site-directed mutants
designed to analyze the mechanism of this medically and commercially important
toxin. The structure of the recombinant protein, rRTA, is virtually identical to
that seen previously for A chain in the heterodimeric toxin. Some minor
conformational changes due to interactions with B chain and to crystal packing
differences are described. Perhaps the most significant difference is the
presence in rRTA of an additional active site water. This molecule is positioned
to act as the ultimate nucleophile in the depurination reaction mechanism
proposed by Monzingo and Robertus (1992, J. Mol. Biol. 227, 1136-1145).
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Figure 2.
Fig. 2. Superposition of the refined
models of ricin Aand rRTA. Recom-
binant RTA, as refinedin this study is
shown in the heavy ondsasa Ca
trace. The refined ricin A chain (Ru-
tenber et al., 1991) is shown in thin
bonds.
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Figure 5.
Fig. 5. The active site of ricin. The conforma-
of ricin A is shown in light bonds and that
f rRTA n heavy bonds.
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The above figures are
reprinted
from an Open Access publication published by the Protein Society:
Protein Sci
(1993,
2,
429-435)
copyright 1993.
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Secondary reference #1
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Title
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Structure of ricin a-Chain at 2.5 a.
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Authors
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B.J.Katzin,
E.J.Collins,
J.D.Robertus.
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Ref.
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Proteins, 1991,
10,
251-259.
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PubMed id
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Secondary reference #2
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Title
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Crystallization of ricin a chain obtained from a cloned gene expressed in escherichia coli.
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Authors
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J.D.Robertus,
M.Piatak,
R.Ferris,
L.L.Houston.
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Ref.
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J Biol Chem, 1987,
262,
19-20.
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PubMed id
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