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Figure 2.
Fig. 2. Three-dimensional structure of CP4 EPSP synthase.
(A) (Left) Unliganded CP4 EPSP synthase exists in an open
conformation. (Right) Upon interaction with S3P, the enzyme
undergoes a large conformational change to a closed state. Shown
in orange is a loop spanning residues 347–358, which is highly
flexible in the open conformation but becomes ordered in the
closed conformation. This loop contains the strictly conserved
EPSP synthase residues Glu-354 and Arg-357, which are involved
in PEP/glyphosate binding. Monovalent cations may influence the
conformation of this loop and facilitate binding of PEP. (B)
Stereoview showing that, in the binary complex, S3P (yellow)
binds to the enzyme residues shown in magenta through multiple
hydrogen-bonding/electrostatic interactions (black dotted
lines). In addition, the cyclohexene moiety of S3P is sandwiched
between Arg-200 and Gln-175. Residues shown in light blue
constitute the PEP/glyphosate binding site. Attracted by the
accumulation of positive charges, a sulfate ion (shown in green)
from the crystallization solution binds to the space occupied by
the phosphate moiety of PEP or the phosphonate moiety of
glyphosate in either ternary complex. Water molecules are shown
as cyan spheres.
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