Telomerase reverse transcriptase thumb DNA binding domain
The catalytic subunit of telomerase is structurally similar to retroviral reverse transcriptases, viral RNA polymerases and, to a lesser extent, the bacteriophage B-family DNA polymerases. Like its structural homologs, the core catalytic subunit of t ...
The catalytic subunit of telomerase is structurally similar to retroviral reverse transcriptases, viral RNA polymerases and, to a lesser extent, the bacteriophage B-family DNA polymerases. Like its structural homologs, the core catalytic subunit of telomerase, TERT, contains the fingers, palm and thumb domains required for nucleic acid and nucleotide associations as well as catalysis. The four major TERT domains: the RNA binding domain (TRBD); the fingers domain, implicated in nucleotide binding and processivity; the palm domain, which contains the active site of the enzyme; and the thumb domain, implicated in DNA binding and processivity are organized into a ring configuration similar to that observed for the substrate-free enzyme. This is the thumb domain found in Tribolium castaneum telomerase catalytic subunit, TERT. Contacts between TERT and the DNA substrate are mostly mediated via backbone interactions with the thumb loop and helix. The thumb helix sits in the minor groove of the RNA-DNA heteroduplex, making extensive contacts with the phosphodiester backbone and the ribose groups of the RNA-DNA hybrid [1, 2].
Reverse transcriptase (RNA-dependent DNA polymerase)
A reverse transcriptase gene is usually indicative of a mobile element such as a retrotransposon or retrovirus. Reverse transcriptases occur in a variety of mobile elements, including retrotransposons, retroviruses, group II introns, bacterial msDNAs ...
A reverse transcriptase gene is usually indicative of a mobile element such as a retrotransposon or retrovirus. Reverse transcriptases occur in a variety of mobile elements, including retrotransposons, retroviruses, group II introns, bacterial msDNAs, hepadnaviruses, and caulimoviruses.
Telomeres in most organisms are comprised of tandem simple sequence repeats [1]. The total length of telomeric repeat sequence at each chromosome end is determined in a balance of sequence loss and sequence addition [1]. One major influence on telome ...
Telomeres in most organisms are comprised of tandem simple sequence repeats [1]. The total length of telomeric repeat sequence at each chromosome end is determined in a balance of sequence loss and sequence addition [1]. One major influence on telomere length is the enzyme telomerase [1]. It is a reverse transcriptase that adds these simple sequence repeats to chromosome ends by copying a template sequence within the RNA component of the enzyme [1]. The RNA binding domain of telomerase - TRBD - is made up of twelve alpha helices and two short beta sheets [2]. How telomerase and associated regulatory factors physically interact and function with each other to maintain appropriate telomere length is poorly understood. It is known however that TRBD is involved in formation of the holoenzyme (which performs the telomere extension) in addition to recognition and binding of RNA [2].
