scholarly journals Excision of 5-Halogenated Uracils by Human Thymine DNA Glycosylase

2007 ◽  
Vol 282 (38) ◽  
pp. 27578-27586 ◽  
Author(s):  
Michael T. Morgan ◽  
Matthew T. Bennett ◽  
Alexander C. Drohat
Keyword(s):  
Potential Role ◽  
Anticancer Agent ◽  
Context Effects ◽  
Maximal Activity ◽  
The Other ◽  
Dna Glycosylase ◽  
Cytotoxic Effects ◽  
Thymine Dna Glycosylase ◽  
Inflammatory Conditions ◽  
Neighbor Effects

Thymine DNA glycosylase (TDG) excises thymine from G·T mispairs and removes a variety of damaged bases (X) with a preference for lesions in a CpG·X context. We recently reported that human TDG rapidly excises 5-halogenated uracils, exhibiting much greater activity for CpG·FU, CpG·ClU, and CpG·BrU than for CpG·T. Here we examine the effects of altering the CpG context on the excision activity for U, T, FU, ClU, and BrU. We show that the maximal activity (kmax) for G·X substrates depends significantly on the 5′ base pair. For example, kmax decreases by 6-, 11-, and 82-fold for TpG·ClU, GpG·ClU, and ApG·ClU, respectively, as compared with CpG·ClU. For the other G·X substrates, the 5′-neighbor effects have a similar trend but vary in magnitude. The activity for G·FU, G·ClU, and G·BrU, with any 5′-flanking pair, meets and in most cases significantly exceeds the CpG·T activity. Strikingly, human TDG activity is reduced 102.3–104.3-fold for A·X relative to G·X pairs and reduced further for A·X pairs with a 5′ pair other than C·G. The effect of altering the 5′ pair and/or the opposing base (G·X versus A·X) is greater for substrates that are larger (bromodeoxyuridine, dT) or have a more stable N-glycosidic bond (such as dT). The largest CpG context effects are observed for the excision of thymine. The potential role played by human TDG in the cytotoxic effects of ClU and BrU incorporation into DNA, which can occur under inflammatory conditions and in the cytotoxicity of FU, a widely used anticancer agent, are discussed.

scholarly journals Simple Thalidomide Analogs in Melanoma: Synthesis and Biological Activity

2021 ◽  
Vol 11 (13) ◽  
pp. 5823
Author(s):  
Alexia Barbarossa ◽  
Alessia Catalano ◽  
Jessica Ceramella ◽  
Alessia Carocci ◽  
Domenico Iacopetta ◽  
...  
Keyword(s):  
Anticancer Agent ◽  
Ring System ◽  
In Vitro Assays ◽  
Tubulin Polymerization ◽  
Cytotoxic Effects ◽  
Ongoing Research ◽  
Drug Candidates ◽  
Small Series ◽  
Clinical Interest

Thalidomide is an old well-known drug that is still of clinical interest, despite its teratogenic activities, due to its antiangiogenic and immunomodulatory properties. Therefore, efforts to design safer and effective thalidomide analogs are continually ongoing. Research studies on thalidomide analogs have revealed that the phthalimide ring system is an essential pharmacophoric fragment; thus, many phthalimidic compounds have been synthesized and evaluated as anticancer drug candidates. In this study, a panel of selected in vitro assays, performed on a small series of phthalimide derivatives, allowed us to characterize compound 2k as a good anticancer agent, acting on A2058 melanoma cell line, which causes cell death by apoptosis due to its capability to inhibit tubulin polymerization. The obtained data were confirmed by in silico assays. No cytotoxic effects on normal cells have been detected for this compound that proves to be a valid candidate for further investigations to achieve new insights on possible mechanism of action of this class of compounds as anticancer drugs.

Pannexin channels and their links to human disease

2014 ◽  
Vol 461 (3) ◽  
pp. 371-381 ◽  
Author(s):  
Silvia Penuela ◽  
Luke Harland ◽  
Jamie Simek ◽  
Dale W. Laird
Keyword(s):  
Infectious Diseases ◽  
Human Disease ◽  
Potential Role ◽  
Germ Line ◽  
Disease Onset ◽  
The Other ◽  
Present Review ◽  
Germ Line Mutations ◽  
Genes Encoding ◽  
Intracellular Compartments

In less than a decade, a small family of channel-forming glycoproteins, named pannexins, have captured the interest of many biologists, in large part due to their association with common diseases, ranging from cancers to neuropathies to infectious diseases. Although the pannexin family consists of only three members (Panx1, Panx2 and Panx3), one or more of these pannexins are expressed in virtually every mammalian organ, implicating their potential role in a diverse array of pathophysiologies. Panx1 is the most extensively studied, but features of this pannexin must be cautiously extrapolated to the other pannexins, as for example we now know that Panx2, unlike Panx1, exhibits unique properties such as a tendency to be retained within intracellular compartments. In the present review, we assess the biochemical and channel features of pannexins focusing on the literature which links these unique molecules to over a dozen diseases and syndromes. Although no germ-line mutations in genes encoding pannexins have been linked to any diseases, many cases have shown that high pannexin expression is associated with disease onset and/or progression. Disease may also occur, however, when pannexins are underexpressed, highlighting that pannexin expression must be exquisitely regulated. Finally, we discuss some of the most pressing questions and controversies in the pannexin field as the community seeks to uncover the full biological relevance of pannexins in healthy organs and during disease.

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

Flavipucine and Brunnescin, Two Antibiotics from Cultures of the Mycophilic Fungus Cladobotryum rubrobrunnescens

1995 ◽  
Vol 50 (5-6) ◽  
pp. 358-364 ◽  
Author(s):  
Christian Wagner ◽  
Heidrun Anke ◽  
Helmut Besla ◽  
Olov Sterner
Keyword(s):  
The Other ◽  
Furan Derivative ◽  
Submerged Cultures ◽  
Cytotoxic Effects ◽  
Aspergillus Flavipes ◽  
Antimicrobial Metabolites ◽  
Agric Biol

Abstract Two antimicrobial metabolites were isolated from submerged cultures of Cladobotryum rubrobrunnescens, a mycophilic fungus growing on a Inocybe species. One of the compounds proved to be identical to flavipucine (2), an antibiotic previously isolated from Aspergillus flavipes (Casinovi et al., 1968) and from a Macrophoma species (Sassa T. and Onuma Y. (1983), Agric. Biol. Chem. 47, 1155-1157). The other metabolite, brunnescin (1), is a new tetrasubstituted furan derivative which exhibits antibacterial, antifungal and cytotoxic effects.

PLCζ, a sperm-specific PLC and its potential role in fertilization

2007 ◽  
Vol 74 ◽  
pp. 23-36 ◽  
Author(s):  
Christopher M. Saunders ◽  
Karl Swann ◽  
F. Anthony Lai
Keyword(s):  
Intracellular Calcium ◽  
Membrane Fusion ◽  
Causative Agent ◽  
Calcium Concentration ◽  
Potential Role ◽  
Vital Role ◽  
The Other ◽  
Sperm Protein ◽  
Dramatic Rise ◽  
The Moment

A dramatic rise in intracellular calcium plays a vital role at the moment of fertilization, eliciting the resumption of meiosis and the initiation of embryo development. In mammals, the rise takes the form of oscillations in calcium concentration within the egg, driven by an elevation in inositol trisphosphate. The causative agent of these oscillations is proposed to be a recently described phosphoinositide-specific phospholipase C, PLCζ, a soluble sperm protein that is delivered into the egg following membrane fusion. In the present review, we examine some of the distinctive structural and functional characteristics of this crucial enzyme that sets it apart from the other known forms of mammalian PLC.

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.

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