G/T mismatch-specific thymine DNA glycosylase is an enzyme that in humans is encoded by the TDGgene.[1][2][3] Several bacterial proteins have strong sequence homology with this protein.[4]
The protein encoded by this gene belongs to the TDG/mug DNA glycosylase family. Thymine-DNA glycosylase (TDG) removes thymine moieties from G/T mismatches by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of DNA and the mispaired thymine. With lower activity, this enzyme also removes thymine from C/T and T/T mispairings. TDG can also remove uracil and 5-bromouracil from mispairings with guanine. This enzyme plays a central role in cellular defense against genetic mutation caused by the spontaneous deamination of 5-methylcytosine and cytosine. This gene may have a pseudogene in the p arm of chromosome 12.[3]
Additionally, in 2011, the human thymine DNA glycosylase (hTDG) was reported to efficiently excises 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), the key oxidation products of 5-methylcytosine in genomic DNA.[5] Later on, the crystal structure of the hTDG catalytic domain in complex with duplex DNA containing 5caC was published, which supports the role of TDG in mammalian 5-methylcytosine demethylation.[6]
Interactions
Thymine-DNA glycosylase has been shown to interact with:
↑Gallinari P, Jiricny J (October 1996). "A new class of uracil-DNA glycosylases related to human thymine-DNA glycosylase". Nature. 383 (6602): 735–8. doi:10.1038/383735a0. PMID8878487.
↑Tini M, Benecke A, Um SJ, Torchia J, Evans RM, Chambon P (February 2002). "Association of CBP/p300 acetylase and thymine DNA glycosylase links DNA repair and transcription". Mol. Cell. 9 (2): 265–77. doi:10.1016/S1097-2765(02)00453-7. PMID11864601.
↑Chen D, Lucey MJ, Phoenix F, Lopez-Garcia J, Hart SM, Losson R, Buluwela L, Coombes RC, Chambon P, Schär P, Ali S (October 2003). "T:G mismatch-specific thymine-DNA glycosylase potentiates transcription of estrogen-regulated genes through direct interaction with estrogen receptor alpha". J. Biol. Chem. 278 (40): 38586–92. doi:10.1074/jbc.M304286200. PMID12874288.
↑Takahashi H, Hatakeyama S, Saitoh H, Nakayama KI (February 2005). "Noncovalent SUMO-1 binding activity of thymine DNA glycosylase (TDG) is required for its SUMO-1 modification and colocalization with the promyelocytic leukemia protein". J. Biol. Chem. 280 (7): 5611–21. doi:10.1074/jbc.M408130200. PMID15569683.
↑Minty A, Dumont X, Kaghad M, Caput D (November 2000). "Covalent modification of p73alpha by SUMO-1. Two-hybrid screening with p73 identifies novel SUMO-1-interacting proteins and a SUMO-1 interaction motif". J. Biol. Chem. 275 (46): 36316–23. doi:10.1074/jbc.M004293200. PMID10961991.
Neddermann P, Jiricny J (1993). "The purification of a mismatch-specific thymine-DNA glycosylase from HeLa cells". J. Biol. Chem. 268 (28): 21218–24. PMID8407958.
Barrett TE, Savva R, Panayotou G, et al. (1998). "Crystal structure of a G:T/U mismatch-specific DNA glycosylase: mismatch recognition by complementary-strand interactions". Cell. 92 (1): 117–29. doi:10.1016/S0092-8674(00)80904-6. PMID9489705.
Missero C, Pirro MT, Simeone S, et al. (2001). "The DNA glycosylase T:G mismatch-specific thymine DNA glycosylase represses thyroid transcription factor-1-activated transcription". J. Biol. Chem. 276 (36): 33569–75. doi:10.1074/jbc.M104963200. PMID11438542.
Tini M, Benecke A, Um SJ, et al. (2002). "Association of CBP/p300 acetylase and thymine DNA glycosylase links DNA repair and transcription". Mol. Cell. 9 (2): 265–77. doi:10.1016/S1097-2765(02)00453-7. PMID11864601.
Abu M, Waters TR (2003). "The main role of human thymine-DNA glycosylase is removal of thymine produced by deamination of 5-methylcytosine and not removal of ethenocytosine". J. Biol. Chem. 278 (10): 8739–44. doi:10.1074/jbc.M211084200. PMID12493755.
Chen D, Lucey MJ, Phoenix F, et al. (2003). "T:G mismatch-specific thymine-DNA glycosylase potentiates transcription of estrogen-regulated genes through direct interaction with estrogen receptor alpha". J. Biol. Chem. 278 (40): 38586–92. doi:10.1074/jbc.M304286200. PMID12874288.
Lehner B, Semple JI, Brown SE, et al. (2004). "Analysis of a high-throughput yeast two-hybrid system and its use to predict the function of intracellular proteins encoded within the human MHC class III region". Genomics. 83 (1): 153–67. doi:10.1016/S0888-7543(03)00235-0. PMID14667819.
Brandenberger R, Wei H, Zhang S, et al. (2005). "Transcriptome characterization elucidates signaling networks that control human ES cell growth and differentiation". Nat. Biotechnol. 22 (6): 707–16. doi:10.1038/nbt971. PMID15146197.
Krześniak M, Butkiewicz D, Samojedny A, et al. (2005). "Polymorphisms in TDG and MGMT genes - epidemiological and functional study in lung cancer patients from Poland". Ann. Hum. Genet. 68 (Pt 4): 300–12. doi:10.1046/j.1529-8817.2004.00079.x. PMID15225156.