Structure and function of telomerase RNA.

Maintenance of telomeres by the enzyme telomerase is essential for genomic stability and cell viability in ciliates, vertebrates and yeast. The minimal components of telomerase required for catalytic activity are the telomerase reverse transcriptase (TERT) protein and the template-containing telomerase RNA (TER). Recent studies have afforded significant advances in the biophysical characterization of telomerase RNAs from various species. The first TER structures have been reported, for regions of the catalytically essential pseudoknot and CR4/CR5 domains of human TER, and provide a structural basis for interpretation of mutational and biochemical data. The domains and interactions of the Tetrahymena thermophila telomerase holoenzyme RNA and protein components have been further characterized biochemically, and structures of the TER template boundary element and the N-terminal domain of T. thermophila TERT have been determined. Phylogenetic and biochemical analyses of yeast TERs have revealed core structural elements in common with ciliates and vertebrates, and the minimal domains required for function in vivo.