scholarly journals Excision of 5-Carboxylcytosine by Thymine DNA Glycosylase

2019 ◽  
Vol 141 (47) ◽  
pp. 18851-18861 ◽  
Author(s):  
Lakshmi S. Pidugu ◽  
Qing Dai ◽  
Shuja S. Malik ◽  
Edwin Pozharski ◽  
Alexander C. Drohat
Keyword(s):  
Dna Glycosylase ◽  
Thymine Dna Glycosylase

scholarly journals SUMO-1 regulates the conformational dynamics of Thymine-DNA Glycosylase regulatory domain and competes with its DNA binding activity

2011 ◽  
Vol 12 (1) ◽  
pp. 4 ◽  
Author(s):  
Caroline Smet-Nocca ◽  
Jean-Michel Wieruszeski ◽  
Hélène Léger ◽  
Sebastian Eilebrecht ◽  
Arndt Benecke
Keyword(s):  
Dna Binding ◽  
Conformational Dynamics ◽  
Binding Activity ◽  
Dna Glycosylase ◽  
Regulatory Domain ◽  
Thymine Dna Glycosylase ◽  
Dna Binding Activity

scholarly journals Insights into the substrate discrimination mechanisms of methyl-CpG-binding domain 4

2021 ◽  
Author(s):  
Hala Ouzon-Shubeita ◽  
Lillian Feigang Schmaltz ◽  
Seongmin Lee
Keyword(s):  
Carbonyl Oxygen ◽  
Binding Domain ◽  
Dna Glycosylase ◽  
Side Chain ◽  
Dna Glycosylases ◽  
Base Pairs ◽  
Thymine Dna Glycosylase ◽  
Mismatched Dna ◽  
Domain 4

G:T mismatches, the major mispairs generated during DNA metabolism, are repaired in part by mismatch-specific DNA glycosylases such as methyl-CpG-binding domain 4 (MBD4) and thymine DNA glycosylase (TDG). Mismatch-specific DNA glycosylases must discriminate the mismatches against million-fold excess correct base pairs. MBD4 efficiently removes thymine opposite guanine but not opposite adenine. Previous studies have revealed that the substrate thymine is flipped out and enters the catalytic site of the enzyme, while the estranged guanine is stabilized by Arg468 of MBD4. To gain further insights into mismatch discrimination mechanism of MBD4, we assessed the glycosylase activity of MBD4 toward various base pairs. In addition, we determined a crystal structure of MBD4 bound to T:O6-methylguanine-containing DNA, which suggests the O6 and N2 of purine and the O4 of pyrimidine are required to be a substrate for MBD4. To understand the role of the Arg468 finger in catalysis, we evaluated the glycosylase activity of MBD4 mutants, which revealed the guanidinium moiety of Arg468 may play an important role in catalysis. D560N/R468K MBD4 bound to T:G mismatched DNA shows that the side chain amine moiety of the Lys stabilizes the flipped-out thymine by a water-mediated phosphate pinching, while the backbone carbonyl oxygen of the Lys engages in hydrogen bonds with N2 of the estranged guanine. Comparison of various DNA glycosylase structures implies the guanidinium and amine moieties of Arg and Lys, respectively, may involve in discriminating between substrate mismatches and nonsubstrate base pairs.

scholarly journals Thymine DNA Glycosylase Can Rapidly Excise 5-Formylcytosine and 5-Carboxylcytosine

2011 ◽  
Vol 286 (41) ◽  
pp. 35334-35338 ◽  
Author(s):  
Atanu Maiti ◽  
Alexander C. Drohat
Keyword(s):  
Embryonic Development ◽  
Catalytic Mechanism ◽  
Excision Repair ◽  
Dna Demethylation ◽  
Oxidation Products ◽  
Dna Glycosylase ◽  
Thymine Dna Glycosylase ◽  
Active Demethylation ◽  
Active Dna Demethylation ◽  
Base Excision

Thymine DNA glycosylase (TDG) excises T from G·T mispairs and is thought to initiate base excision repair (BER) of deaminated 5-methylcytosine (mC). Recent studies show that TDG, including its glycosylase activity, is essential for active DNA demethylation and embryonic development. These and other findings suggest that active demethylation could involve mC deamination by a deaminase, giving a G·T mispair followed by TDG-initiated BER. An alternative proposal is that demethylation could involve iterative oxidation of mC to 5-hydroxymethylcytosine (hmC) and then to 5-formylcytosine (fC) and 5-carboxylcytosine (caC), mediated by a Tet (ten eleven translocation) enzyme, with conversion of caC to C by a putative decarboxylase. Our previous studies suggest that TDG could excise fC and caC from DNA, which could provide another potential demethylation mechanism. We show here that TDG rapidly removes fC, with higher activity than for G·T mispairs, and has substantial caC excision activity, yet it cannot remove hmC. TDG excision of fC and caC, oxidation products of mC, is consistent with its strong specificity for excising bases from a CpG context. Our findings reveal a remarkable new aspect of specificity for TDG, inform its catalytic mechanism, and suggest that TDG could protect against fC-induced mutagenesis. The results also suggest a new potential mechanism for active DNA demethylation, involving TDG excision of Tet-produced fC (or caC) and subsequent BER. Such a mechanism obviates the need for a decarboxylase and is consistent with findings that TDG glycosylase activity is essential for active demethylation and embryonic development, as are mechanisms involving TDG excision of deaminated mC or hmC.

The Thymine−DNA Glycosylase Regulatory Domain: Residual Structure and DNA Binding†

Biochemistry ◽  
2008 ◽  
Vol 47 (25) ◽  
pp. 6519-6530 ◽  
Author(s):  
Caroline Smet-Nocca ◽  
Jean-Michel Wieruszeski ◽  
Vicky Chaar ◽  
Arnaud Leroy ◽  
Arndt Benecke
Keyword(s):  
Dna Binding ◽  
Dna Glycosylase ◽  
Regulatory Domain ◽  
Thymine Dna Glycosylase ◽  
Residual Structure

Cyclic enzymatic repairing-mediated dual-signal amplification for real-time monitoring of thymine DNA glycosylase

2017 ◽  
Vol 53 (27) ◽  
pp. 3878-3881 ◽  
Author(s):  
Li-Juan Wang ◽  
Zi-Yue Wang ◽  
Qianyi Zhang ◽  
Bo Tang ◽  
Chun-Yang Zhang
Keyword(s):  
Real Time ◽  
Signal Amplification ◽  
Fluorescence Method ◽  
Dna Glycosylase ◽  
Real Time Monitoring ◽  
Thymine Dna Glycosylase ◽  
Dual Signal Amplification

We develop a new fluorescence method for real-time monitoring of thymine DNA glycosylase activity through cyclic enzymatic repairing-mediated dual-signal amplification.

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