The architecture of Tetrahymena telomerase holoenzyme

The ends of linear chromosomes in eukaryotes are maintained by a ribonucleoprotein complex known as telomerase. Juli Feigon and colleagues have obtained a long-awaited structure of the ciliate (Tetrahymena thermophila) telomerase by electron microscopy. Modelling with crystal structures of various components allowed identification of the catalytic core and subunit interactions, and a complete in vitro reconstitution of the enzyme was performed. The structure provides unprecedented detail about the architecture of the ribonucleoprotein catalytic core and reveals the organization of holoenzyme subunits that confer processivity and bridge telomerase to telomeres.