model for phosphoryl transfer and
product release. (J. Gan, G. Shaw, J.E. Tropea, D.S. Waugh, D.L.
Court and X.
Ji, Mol. Microbiol. 2008; 67:143-154. Abstract). (A)
Model of the protein-substrate complex. (B) Model of the
intermediate complex (transition state). (C) The catalytic site
immediately after dsRNA cleavage is represented by the minor
the Aa-RNase III•MgRNA 9 structure. (D) Step 1 toward product
represented by the major conformation of the Aa-RNase III•MgRNA 9
(E) Step 2 toward product release is represented by the Aa-RNase
structure. The aa and nt residues are shown as stick models and Mg2+
ions and water oxygens as spheres (C, gray; N, blue; O, red; P, orange;
black). Metal coordination bonds are illustrated as solid lines and
bonds as dashed lines. The nt residue in the middle is numbered
“R 0” and the
rest are numbered according to the polarity of the RNA strand.