FIGURE 8.

Mutation-induced structural changes in EPSPS (stereo views). Top: EPSPS in complex with S3P. In the WT enzyme binary complex (shown in orange) Thr⁹⁷ is in hydrogen bonding distance (2.8 Å) to the amide side chain of Asn⁹⁶. In the T97I enzyme binary complex (maroon) the presence of the Pro¹⁰¹ ring holds Ile⁹⁷ in place, and its side chain moves only slightly. In the TIPS enzyme binary complex (cyan) Ser¹⁰¹ allows larger conformational freedom for Ile⁹⁷, and the isoleucine side chain swings away from Asn²⁶. Bottom: EPSPS in complex with S3P and glyphosate bound. In the ternary complex, the mutations cause a shift of the Cα atom of Gly⁹⁶ toward the phosphonate moiety of glyphosate, seen most drastically in the TIPS enzyme (cyan), thereby narrowing the inhibitor binding site. The view is ∼90° clockwise from the top.