Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): A pseudoknot in telomerase RNA of the budding yeast Kluyveromyces lactis contains an essential major-groove triple helix. A molecular model of the pseudoknot structure indicates the Watson and Crick strands of the triplex in red and yellow and the third strand in cyan. Triple compensatory mutations preserving the triple-helix structure resulted in a smooth-colony phenotype typical of a wild-type strain (right). However, similar mutations that altered the positioning of the third strand resulted in a rough-colony phenotype, typical of telomerase-deficient strains (left). The pseudoknot model was calculated with the computer program miniCarlo and displayed with UCSF Chimera. (See related article on page 2130.)