Figure 5.
Figure 5 Stereo diagrams showing details of the electron density
of T-loop residues and the nucleotide-binding pocket at the
interface between two adjacent GlnK1 monomers (blue and green).
(A) Without added Mg-ATP, occasional sites are occupied by ADP
(red) or AMP from the expressing cells. The T-loop is in an
extended conformation, with arginines 45, 47 and 49 and Tyr51at
the tip. (B) Mg-ATP (red) fixes the T-loop in the compact
conformation through main-chain interactions with the ATP -phosphate
and hydrogen bonds with Mg-coordinated water molecules,
positioning Glu44 to form a salt bridge with Lys58. (C) By
fixing the T-loop in its compact conformation, Mg-ATP (red)
creates a binding site for 2-KG (yellow) on the far side of
Tyr51. The density above the keto oxygen of 2-KG is due to an
ordered water molecule.
-phosphate
and hydrogen bonds with Mg-coordinated water molecules,
positioning Glu44 to form a salt bridge with Lys58. (C) By
fixing the T-loop in its compact conformation, Mg-ATP (red)
creates a binding site for 2-KG (yellow) on the far side of
Tyr51. The density above the keto oxygen of 2-KG is due to an
ordered water molecule.