Activation-induced cytidine deaminase is required for the DNA cleavage step of Ig class switch recombination (CSR). However, its molecular mechanism is controversial. RNA-editing hypothesis postulates that activation-induced cytidine deaminase deaminates cytosine in an unknown mRNA to generate a new mRNA encoding an endonuclease for CSR and thus predicts that DNA cleavage depends on de novo pro...

The prodrug activation system formed by the E. coli codA gene encoding cytosine deaminase (CD) and 5-fluorocytosine (5-FC) developed for selective cancer chemotherapy suffers from a sensitivity limitation in many tumour cells. In an attempt to improve the CD/5-FC suicide association, we combined the E. coli upp gene encoding uracil phosphoribosyltransferase (UPRT) with codA gene to create the s...

Population studies have indicated that natural resistance to flucytosine (5FC) in Candida albicans is limited to one of the five major clades, clade I. In addition, while 73% of clade I isolates are less susceptible to 5FC (MIC >/= 0.5 microg/ml), only 2% of non-clade I isolates are less susceptible. In order to determine the genetic basis for this clade-specific resistance, we sequenced two ge...

Uracil-DNA glycosidase, an enzyme that catalyzes the release of free uracil from uracil-containing DNA, has been purified ll,OOO-fold from Escherichia coli cell extracts. The enzyme preparation was essentially homogenous, as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The native enzyme is a small monomeric protein of a molecular weight of 24,500 + 1,000. The enzyme e...

In this work we investigate different forms of electron binding in the mass-selected and cooled nucleobases uracil, thymine and cytosine and their water clusters. In photodetachment–photoelectron spectra of the pyrimidine nucleobases, Ž . Ž . Ž . sharp structures were found at 86"8 meV uracil , 62"8 meV thymine and 85"8 meV cytosine , which are due to photodetachment of dipole-bound states. The...

DNA cytosine methylation is one of the most abundant epigenetic marks found in the plant nuclear genome. Bisulfite sequencing (BS-Seq) is the method of choice for profiling DNA cytosine methylation genome-wide at a single nucleotide resolution. The basis of this technique is that the unmethylated cytosine can be deaminated to uracil by sodium bisulfite, while the methylated cytosine is resistan...

Genomic uracil is a DNA lesion but also an essential key intermediate in adaptive immunity. In B cells, activation-induced cytidine deaminase deaminates cytosine to uracil (U:G mispairs) in Ig genes to initiate antibody maturation. Uracil-DNA glycosylases (UDGs) such as uracil N-glycosylase (UNG), single strand-selective monofunctional uracil-DNA glycosylase 1 (SMUG1), and thymine-DNA glycosyla...

We developed a high-throughput quantitative capillary assay and demonstrated that Pseudomonas putida strains F1 and PRS2000 were attracted to cytosine, but not thymine or uracil. In contrast, Pseudomonas aeruginosa PAO1 was not chemotactic to any pyrimidines. Chemotaxis assays with a mutant strain of F1 in which the putative methyl-accepting chemotaxis protein-encoding gene Pput_0623 was delete...

Most of the literature dealing with the participation of citrovorum factor and vitamin Blz in the formation and transfer of l-carbon intermediates stresses the donor compounds serine, glycine, and formate as precursors of the 5-methyl group of thymidine (2). Uracil deoxyriboside, first isolated in crystalline form by Dekker and Todd (3) in 1950, is known to arise as a result of the deamination ...

Uracil may occur in DNA due to either cytosine deamination or thymine replacing incorporation. Its quantitative characterization is important in assessing DNA damages in cells with perturbed thymidylate metabolism or within different DNA segments involved in immunoglobulin gene diversification. The archaeal DNA polymerase from Pyrococcus furiosus binds strongly to the deaminated base uracil and...