The structure of the human telomerase enzyme is reported in Nature this week. With telomerase implicated in cancer and ageing, the findings represent an important step towards the development of telomerase-related therapies.

Telomeres are the protective caps found at the end of chromosomes. They have been likened to the plastic tips found on shoelaces, because they prevent chromosomes from ‘fraying.’ Every time a cell divides, the telomeres become shorter until eventually the cell stops dividing and dies. Telomerase can prevent this by adding DNA to the chromosome tips.

Kathleen Collins and colleagues used cryo-electron microscopy, in which beams of electrons are fired at proteins that have been frozen in solution, in order to determine the enzyme’s structure. Progress towards clinical manipulation of telomerase has been hampered by a lack of structural data. Here, the molecule is pictured bound to its substrate at sub-nanometre scale, making it the highest resolution image of the telomerase enzyme to date.