Figure 4

Conformation of the PTC. (A) Different orientations of A2062 and its local environment for native D50S (purple), for the complex with Synercid^® (blue) and for the H50S streptogramin complex (yellow). (B) Comparison of the position of dalfopristin in D50S (orange) with the position of virginiamycin M in H50S (light green), and the corresponding folds of 23S rRNA in the vicinity of U2585 (in blue for D50S and in yellow for H50S). (C) Structure and electron density around U2585. For comparison, the orientation of U2585 in the native D50S structure is also shown. The electron density is a sigmaA weighted difference map omitting the whole peptidyl-transferase ring from the calculation. (D) Local structure around U2585 overlaid with the native structure; putative hydrogen bonds of U2585 in its new orientation are indicated. (E) Approximate energy profile derived from modelling intermediate conformations, units being arbitrary. N indicates the energy of the native conformation and S the one of the complex with Synercid^®.