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Figure 3.
Figure 3. The Chorismate Synthase Active Site(A) Stereo
representation of interactions made by FMN in the closed form.
Active site residues are shown with green carbon atoms, FMN and
EPSP with gray carbon atoms. Red spheres represent conserved
water positions. Hydrogen bonds are shown as dashed lines. Some
residues shown are from an adjacent monomer and form
interactions that may stabilize the CS dimer. These residues are
shown in darker green, and are labeled with green text, while
residues from the monomer, which forms the majority of the
active site, have black labels.(B) Stereo representation of
interactions made by EPSP in the closed form. Active site
residues are shown with green carbon atoms, FMN and EPSP with
gray carbon atoms. Red spheres represent conserved water
positions. Hydrogen bonds are shown as dashed lines.(C) Stereo
diagram of the overlaid Ca traces of open (cyan ribbon) and
closed (green ribbon) forms, showing differences in the
conformations of loops L20 and L22. EPSP and FMN are shown with
gray carbon atoms. The side chains of residues His 110, Tyr 317,
Arg 337, Ser 338, and Asp 339 are shown for both forms (Open
form: cyan carbons, closed form: green carbons). L22 shows the
most significant movement, as demonstrated by the changes in the
position of Arg 337 and Ser 338. Tyr 317 on loop L20 adopts
different side chain conformations in open and closed forms, and
may have a role in maintaining the closed conformation of loop
L22. Hydrogen bond interactions between ligands and the
highlighted residues in the closed form are shown as dashed
lines. Corresponding interactions in the open form are omitted
for clarity.
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