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Title
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Identical mutations at corresponding positions in two homologous proteins with nonidentical effects.
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Authors
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A.J.Björkman,
R.A.Binnie,
L.B.Cole,
H.Zhang,
M.A.Hermodson,
S.L.Mowbray.
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Ref.
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J Biol Chem, 1994,
269,
11196-11200.
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PubMed id
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Abstract
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The x-ray structure of a mutant (Gly72 to Asp) of the Escherichia coli
ribose-binding protein with altered transport function has been solved and
refined to 2.2-A resolution with a conventional R-factor (R-factor = [formula:
see text]) of 16.0% and good stereochemistry. Comparison with the wild type
ribose-binding protein shows that the structure is disturbed little at the
actual mutation site, but quite appreciably in a neighboring loop. Changes in
the surface of the protein at the site of mutation, however, seem to explain the
functional effects. A corresponding mutation of the related
glucose/galactose-binding protein has different structural and functional
effects due to the different structural context of the mutation site in that
protein. These results are consistent with the concept that these proteins have
slightly different ways of interacting with the membrane components in transport
and chemotaxis.
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