FIG 1.

Location of residue P73 in CNV and associated density in the 3.0-Å X-ray structure at the putative zinc binding region at the quasi-6-fold axis. The top figure is a stereo pair and represents the crystal structure of C subunit termini involved in zinc binding with the RNA interior toward the bottom of the figure. For clarity, the backbone atoms are shown in green, yellow, and mauve for the three C subunits. The model has two alternative positions for zinc based on the electron density, and these are represented by mauve spheres. At bottom is the sequence alignment of various tombusviruses in that region. CyRSV, cymbidium ringspot tombusvirus; TCV, turnip crinkle virus; MNSV, melon necrotic spot virus; RCNMV, red clover necrotic mosaic virus; CLSV, cucumber leaf spot virus; PoLV, pathos latent virus.