Telomere architecture.

Telomeres are protein-DNA complexes that cap chromosome ends and protect them from being recognized and processed as DNA breaks. Loss of capping function results in genetic instability and loss of cellular viability. The emerging view is that maintenance of an appropriate telomere structure is essential for function. Structural information on telomeric proteins that bind to double and single-stranded telomeric DNA shows that, despite a lack of extensive amino-acid sequence conservation, telomeric DNA recognition occurs via conserved DNA-binding domains. Furthermore, telomeric proteins have multidomain structures and hence are conformationally flexible. A possibility is that telomeric proteins take up different conformations when bound to different partners, providing a simple mechanism for modulating telomere architecture.