Divergence of AMP Deaminase in the Ice Worm Mesenchytraeus solifugus (Annelida, Clitellata, Enchytraeidae)
Figure 3
Conformation near the catalytic zinc atom and the AMP-binding pocket, and the phosphate effector site. (a) The zinc atom shows a trigonal bipyramidal conformation ligating coformycin -phosphate, three histidines (H97, H99 and H389), and one aspartic acid (D445). In yellow (space filling model) the specific ice worm substitution F304L. Phe170 and Tyr174 displace the ribose ring of coformycin -phosphate, and Lys169, Lys173, Arg182, Asp444 and Glu448 are able to stabilize the phosphate group of coformycin -phosphate by generating a hydrophilic pocket around this moiety. In yellow (space filling model) the nonconservative ice-worm substitution K188E. Arrows identify residues shifted with respect to those in A. thaliana AMPD. The catalytic zinc is represented by a yellow sphere, the coformycin -phosphate and phosphate ion as stick models. (b) Interaction of the phosphate ion with neighboring amino acid residues (Lys213, Arg92 and Arg86). In yellow (space filling model) is the single specific N216K ice worm substitution.
