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Title
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Escherichia coli PII protein: purification, crystallization and oligomeric structure.
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Authors
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S.G.Vasudevan,
C.Gedye,
N.E.Dixon,
E.Cheah,
P.D.Carr,
P.M.Suffolk,
P.D.Jeffrey,
D.L.Ollis.
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Ref.
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FEBS Lett, 1994,
337,
255-258.
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PubMed id
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Abstract
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The Escherichia coli signal transduction protein PII, product of the glnB gene,
was overproduced and purified. The predicted molecular weight of the protein
based on the correct nucleotide sequence is 12,427 and is very close to the
value 12,435 obtained by matrix-assisted laser desorption mass spectrometry.
Hexagonal crystals of the unuridylylated form of PII with dimensions 0.2 x 0.2 x
0.3 mm were grown and analysed by X-ray diffraction. The crystals belong to
space group P6(3) with a = b = 61.6 A, c = 56.3 A and Vm of 2.5 for one subunit
in the asymmetric unit. A low-resolution electron density map showed electron
density concentrated around a three-fold axis, suggesting the molecule to be a
trimer. A sedimentation equilibrium experiment of the meniscus depletion type
was used to estimate a molecular weight of 35,000 +/- 1,000 for PII in solution.
This result is consistent with the native protein being a homotrimer.
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