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Title
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Crystal structure of intact elongation factor EF-Tu from Escherichia coli in GDP conformation at 2.05 A resolution.
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Authors
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H.Song,
M.R.Parsons,
S.Rowsell,
G.Leonard,
S.E.Phillips.
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Ref.
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J Mol Biol, 1999,
285,
1245-1256.
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PubMed id
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Abstract
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The crystal structure of intact elongation factor Tu (EF-Tu) from Escherichia
coli in GDP-bound conformation has been determined using a combination of
multiple isomorphous replacement (MIR) and multiwavelength anomalous diffraction
(MAD) methods. The current atomic model has been refined to a crystallographic R
factor of 20.3 % and free R-factor of 26.8 % in the resolution range of 10-2.05
A. The protein consists of three domains: domain 1 has an alpha/beta structure;
while domain 2 and domain 3 are beta-barrel structures. Although the global fold
of the current model is similar to those of published structures, the secondary
structural assignment has been improved due to the high quality of the current
model. The switch I region (residues 40-62) is well ordered in this structure.
Comparison with the structure of EF-Tu in GDP-bound form from Thermus aquaticus
shows that although the individual domain structures are similar in these two
structures, the orientation of domains changes significantly. Interactions
between domains 1 and 3 in our E. coli EF-Tu-GDP complex are quite different
from those of EF-Tu with bound GTP from T. aquaticus, due to the domain
rearrangement upon GTP binding. The binding sites of the Mg2+ and guanine
nucleotide are revealed in detail. Two water molecules that co-ordinate the Mg2+
have been identified to be well conserved in the GDP and GTP-bound forms of
EF-Tu structures, as well as in the structure of Ras p21 with bound GDP.
Comparisons of the Mg2+ binding site with other guanine nucleotide binding
proteins in GDP-bound forms show that the Mg2+ co-ordination patterns are well
preserved among these structures.
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