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From Proteopedia
Solution Structure Of The DNA Complex Of Human Trf2
Structural highlights
Function[TERF2_HUMAN] Binds the telomeric double-stranded 5'-TTAGGG-3' repeat and plays a central role in telomere maintenance and protection against end-to-end fusion of chromosomes. In addition to its telomeric DNA-binding role, required to recruit a number of factors and enzymes required for telomere protection, including the shelterin complex, TERF2IP/RAP1 and DCLRE1B/Apollo. Component of the shelterin complex (telosome) that is involved in the regulation of telomere length and protection. Shelterin associates with arrays of double-stranded 5'-TTAGGG-3' repeats added by telomerase and protects chromosome ends; without its protective activity, telomeres are no longer hidden from the DNA damage surveillance and chromosome ends are inappropriately processed by DNA repair pathways. Together with DCLRE1B/Apollo, plays a key role in telomeric loop (T loop) formation by generating 3' single-stranded overhang at the leading end telomeres: T loops have been proposed to protect chromosome ends from degradation and repair. Required both to recruit DCLRE1B/Apollo to telomeres and activate the exonuclease activity of DCLRE1B/Apollo. Preferentially binds to positive supercoiled DNA. Together with DCLRE1B/Apollo, required to control the amount of DNA topoisomerase (TOP1, TOP2A and TOP2B) needed for telomere replication during fork passage and prevent aberrant telomere topology. Recruits TERF2IP/RAP1 to telomeres, thereby participating in to repressing homology-directed repair (HDR), which can affect telomere length.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMammalian telomeres consist of long tandem arrays of double-stranded telomeric TTAGGG repeats packaged by the telomeric DNA-binding proteins TRF1 and TRF2. Both contain a similar C-terminal Myb domain that mediates sequence-specific binding to telomeric DNA. In a DNA complex of TRF1, only the single Myb-like domain consisting of three helices can bind specifically to double-stranded telomeric DNA. TRF2 also binds to double-stranded telomeric DNA. Although the DNA binding mode of TRF2 is likely identical to that of TRF1, TRF2 plays an important role in the t-loop formation that protects the ends of telomeres. Here, to clarify the details of the double-stranded telomeric DNA-binding modes of TRF1 and TRF2, we determined the solution structure of the DNA-binding domain of human TRF2 bound to telomeric DNA; it consists of three helices, and like TRF1, the third helix recognizes TAGGG sequence in the major groove of DNA with the N-terminal arm locating in the minor groove. However, small but significant differences are observed; in contrast to the minor groove recognition of TRF1, in which an arginine residue recognizes the TT sequence, a lysine residue of TRF2 interacts with the TT part. We examined the telomeric DNA-binding activities of both DNA-binding domains of TRF1 and TRF2 and found that TRF1 binds more strongly than TRF2. Based on the structural differences of both domains, we created several mutants of the DNA-binding domain of TRF2 with stronger binding activities compared to the wild-type TRF2. Comparison between TRF2 and TRF1 of their telomeric DNA-bound structures and DNA-binding activities.,Hanaoka S, Nagadoi A, Nishimura Y Protein Sci. 2005 Jan;14(1):119-30. PMID:15608118[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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