Telomere-binding proteins (also known as TERF, TRBF, TRF) function to bind telomeric DNA in various species.
[2] TRFs are double-stranded proteins which are known to induce bending, looping, and pairing of DNA which aids in the formation of T-loops.
The DNA-binding proteins include TERF1, TERF2, and POT1, which have specific sequences, altering binding affinity or regulatory mechanisms.
[6] Both TRFs are separate homodimer proteins, similar to the Myb helix-turn-helix motif with DNA binding folds at the C-terminus.
[5] Telomere-binding proteins function to generate a T-loop, which is a specialized loop structure to cap the telomeric ends.
[9] They serve as a protective safeguard against premature degradation as the telomere ends are no longer hidden from damage detection.
Telomere-binding proteins not present may cause the exposed telomeres to undergo a DNA repair response, having mistakenly identified the ends as a double-stranded break.
[7] TERF1 also serves to prevent problematic secondary structures from hindering progression by interacting with helicase for unobstructed unwinding.
As a result, a cascade of interactions follows by recruiting POT1 and RAP1 and the shelterin complex is complete to protect and regulate the telomeric ends.
As well, damage detection will mediate non-homologous end joining (NHEJ), producing an end-to-end fusion of double-stranded breaks.
The presence of TERF2 then initiates XPF activity leading to the excision of telomeric ends causing a reduction in length.
When exposed to light, notable observations showed hyperpigmentation and skin tumour similar to human syndrome xeroderma pigmentosum.
Telomere shortening was attributed to XPF, an excision repair nuclease, with link to TERF2 causing genomic instability.
By targeting the telomere-binding proteins which serve to protect the ends, it may prove fruitful in future drug therapy.