Overall structure of IspF. IspF forms a homotrimer. a) Axial view. b) Side view. The figure has been drawn using the coordinates for Pf IspF in complex with CDP; a trimer has been generated from symmetry-related subunits. Subunits (displayed as ribbons) are colored blue, orange and green respectively. Zn2+ cations are displayed as grey spheres, sulfate and CDP are displayed as sticks. The secondary structure of Pf IspF and Bc IspF subunits is shown in c) and d) respectively, similarly orientated. The location of missing loops is highlighted with arrows.