Telomerase - Structure

Structure

Human telomerase consists of two molecules each of human telomerase reverse transcriptase (TERT), telomerase RNA (TR or TERC), and dyskerin (DKC1). The genes of telomerase subunits, which are TERT, TERC, DKC1, and TEP1 etc, are located on different chromosomes in the human genome. Human TERT gene (hTERT) is translated into a protein of 1132 amino acids. TERT proteins from many eukaryotes have been sequenced. TERT polypeptide folds with TERC, a non-coding RNA (451 nucleotides long in human). TERT has a 'mitten' structure that allows it to wrap around the chromosome to add single-stranded telomere repeats.

TERT is a reverse transcriptase, which is a class of enzyme that creates single-stranded DNA using single-stranded RNA as a template. Enzymes of this class (not TERT specifically, but the ones isolated from viruses) are utilized by scientists in the molecular biological process of reverse transcriptase PCR (RT-PCR), which allows the creation of several DNA copies of a target sequence using RNA as a template. As stated above, TERT carries its own template around, TERC.

The protein composition of human telomerase was identified in 2007 by Scott Cohen and his team at the Children's Medical Research Institute in Australia. The high-resolution protein structure of the Tribolium castaneum catalytic subunit of telomerase TERT was decoded in 2008 by Emmanuel Skordalakes and his team at The Wistar Institute in Philadelphia. The structure revealed that the protein consists of four conserved domains (RNA-Binding Domain (TRBD), fingers, palm and thumb), organized into a ring configuration that shares common features with retroviral reverse transcriptases, viral RNA polymerases and bacteriophage B-family DNA polymerases.