Cover photograph (Copyright © 2000, American Society for Microbiology. All rights reserved.): A computer-generated ribbon diagram of the KH1 domain in the herpes simplex virus ICP27 protein (blue) was superimposed on a ribbon diagram of the crystal structure of the KH1 RNA-binding domain of Fmr1 (fragile X mental retardation gene) (yellow). Intragenic suppressors of a ts mutation in the KH3 domain of ICP27 map to the KH1 and KH3 domains. These mutations all lie along one face of the KH domains. This surface may represent an interaction interface between these domains and their targets. (See related article on page 2814.)