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![[Figure 4]](cb5114fig4mag.jpg)
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Figure 4
Conformational changes observed upon CDP binding in VcCMAS. (a) Superimposition of the apo VcCMAS dimer (protomers colored split pea and pink) on the CDP-bound form (protomers colored gold and yellow) illustrates the movement of the dimerization domain, which places the catalytic Arg169 close to the active site. The circle marks the dimerization domain and the active site. CDP and the Mg2+ ion are shown in stick representation and as a sphere, respectively. (b) The molecular interactions that stabilize the dimerization domain movement include hydrogen-bond interactions between Gln177 and Thr143 and between Pro178 and His142 via a water molecule. The backbone of the catalytic Arg169 moves 4.6 Å closer (blue dashed line) to the active site and the side-chain guanidino group maintains its interactions with the backbone of Pro140 and Thr141. Superimposition of CMP- and Neu5Ac2en-bound NmCMAS (PDB entry 6ckl) on the VcCMAS structure suggests that the side chain of the catalytic arginine (gray) moves towards the active site only upon substrate binding. Hydrogen bonds are shown as red dashed lines and their lengths are shown in Å. |
![[Figure 4]](cb5114fig4.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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