Structure of active dimeric human telomerase
Open Access
- 10 March 2013
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature Structural & Molecular Biology
- Vol. 20 (4), 454-460
- https://doi.org/10.1038/nsmb.2530
Abstract
EM analyses reveal the three-dimensional structure of human telomerase. Along with functional biochemistry data, the work reveals that telomerase is dimeric in its active form. Each of the two TERT subunits can bind telomeric DNA substrates, and both active sites are required for function. Telomerase contains a large RNA subunit, TER, and a protein catalytic subunit, TERT. Whether telomerase functions as a monomer or dimer has been a matter of debate. Here we report biochemical and labeling data that show that in vivo–assembled human telomerase contains two TERT subunits and binds two telomeric DNA substrates. Notably, catalytic activity requires both TERT active sites to be functional, which demonstrates that human telomerase functions as a dimer. We also present the three-dimensional structure of the active full-length human telomerase dimer, determined by single-particle EM in negative stain. Telomerase has a bilobal architecture with the two monomers linked by a flexible interface. The monomer reconstruction at 23-Å resolution and fitting of the atomic structure of the TERT subunit from beetle Tribolium castaneum into the EM density reveals the spatial relationship between RNA and protein subunits, providing insights into telomerase architecture.Keywords
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