Figure 7 - full size

 

Figure 7.
Fig. 7. (a) Model of DNA-cleavage mechanism of HincII. M1 and M2 mark the two metal ion binding sites. Dashes indicate direct ligation to a metal ion or hydrogen bond from the 3′P to the nucleophilic water, shown as a pink sphere marked nuc. The scissile bond is colored red. (b) Cartoon of the connection between the CSPS and the distance between the phosphorus of the phosphate at the scissile phosphodiester bond (SP) and the phosphate 3′ from the SP (3′P). Dashes indicate direct ligation to the metal ion, M1, or hydrogen bond from the 3′P to the nucleophile (water or hydroxide molecule) shown as a pink sphere. Left: inactive conformation with the 3′P blocking the nucleophile binding site on the M1 ion. Right: active conformation where disruption of the CSPS separates SP from 3′P on each strand to allow the nucleophile to bind to the M1 ion. The scissile bond is shown in red.

The above figure is reprinted from an Open Access publication published by Elsevier: J Mol Biol (2008, 383, 186-204) copyright 2008.