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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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Abstract
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Ricin is a heterodimeric toxin of the form AB, where B is a lectin which binds
cell surfaces, triggering endocytosis. The B chain then aids the A chain in
escaping from the endosome. The A chain enzymatically attacks and inactivates
ribosomes, thereby killing the intoxicated cell. We have recently solved the
three-dimensional structure of whole ricin. Here we report that the A chain,
expressed from a gene cloned into Escherichia coli has been crystallized in a
suitable form for high resolution x-ray analysis. The crystals are monoclinic
space group P2(1) with a = 42.6, b = 68.1, c = 50.2 A and beta = 112.9 degrees.
There is evidence that the A chain undergoes a conformational change, resulting
in activation, when it is released from the B chain. Comparison of the two
structures should facilitate an analysis of this process.
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