Supplementary Figure 3: Conformational changes of BcsA's gating loop.
From: Mechanism of activation of bacterial cellulose synthase by cyclic di-GMP
(a) Sequence conservation of the gating loop. The “FxVTxK” motif is conserved in pro- and eukaryotic cellulose synthases. (b) Unbiased SigmaA-weighted 2mFo-DFc electron density for the gating loop in the “up” position shown as a magenta mesh and contoured at 1σ. The density was calculated before modeling the gating loop. The position of the loop's backbone is well resolved (colored cyan). The side chains of Phe503 and Val505 pack into a hydrophobic pocket on IF2 and are well resolved in the original density map. (c and d) Unbiased SigmaA-weighted mFo-DFc difference electron density for the gating loop in the “down” position and UDP, shown as a magenta mesh. The density was calculated before modeling the gating loop and placing UDP/Mg and is contoured at 2.5σ and 3σ for the gating loop and UDP, respectively. The position of the entire gating loop backbone is well resolved and so are the side chains of the conserved Phe503, Val505, Thr506 and Lys508. Additional electron density between the UDP β-phosphate and BcsA's “DxD'” motif is consistent with a bound magnesium ion (shown as a green sphere). UDP is shown in sticks colored violet for the carbon atoms and the gating loop is colored green. (e) Front and side view comparing the three gating loop positions observed in the resting and c-di-GMP bound states. BcsA is shown as a gray surface with the PilZ domain shown as a red cartoon. The three gating loop positions are shown as cartoons and indicated with their respective colors.
