The resection of DNA strand with a 5´ end at double-strand breaks is an essential step in recombinational DNA repair. RecJ, a member of DHH family proteins, is the only 5´ nuclease involved in the RecF recombination pathway. Here, we report the crystal structures of Deinococcus radiodurans RecJ in complex with deoxythymidine monophosphate (dTMP), ssDNA, the C-terminal region of single-stranded ...

YhdE is a Maf-like (multicopy associated filamentation) protein that primarily acts as dTTPase to hydrolyze dTTP into dTMP and two phosphate molecules in cell metabolism pathway. Two crystal structures of YhdE have been previously determined, representing the open and closed active site conformations, respectively. Based on the structures, we have carried out molecular dynamics simulations and ...

The synthesis of a caged RNA phosphoramidite building block containing the oxidatively damaged base 5-hydroxycytidine (5-HOrC) has been accomplished. To determine the effect of this highly mutagenic lesion on complementary base recognition and coding properties, this building block was incorporated into a 12-mer oligoribonucleotide for T(m) and CD measurements and a 31-mer template strand for p...

Thymidylate synthase (TS) catalyzes the reductive methylation of 2’deoxyuridylate (dUMP) with cofactor 5,10-methylene-5, 6, 7, 8-tetrahydrofolate, forming thymidine monophosphate (dTMP) and 7, 8-dihydrofolate. The reaction pathway is comprised of at least seven covalent bond cleavage or formation, therefore, it is a very complex system for scientists to explore the mechanistic details of this r...

Thymidylate synthase (TS) catalyses the reductive methylation of dUMP to form dTMP, a reaction that is essential for maintenance of nucleotide pools during cell growth. Because the enzyme is indispensable for DNA replication in actively dividing cells, it is an important target for cytotoxic drugs used in cancer chemotherapy, including fluoropyrimidines (e.g. 5-fluorouracil and 5-fluoro-2'-deox...

The size of the DNA product synthesized by RNA-directed DNA polymerase (isolated from avian myeloblastosis virus) was found to be important for complementary DNA (cDNA)-mRNA hybridization reactions. Incomplete cDNA to rabbit reticulocyte globin mRNA formed poor hybrids and presumably lacked sequences needed for hybridization. The size of the cDNA synthesized was influenced by the reaction condi...

The intravascular trematode Schistosoma mansoni is a causative agent of schistosomiasis, a disease that constitutes a major health problem globally. In this study we cloned and characterized the schistosome tegumental phosphodiesterase SmNPP-5 and evaluated its role in parasite virulence. SmNPP-5 is a 52.5-kDa protein whose gene is rapidly turned on in the intravascular parasitic life stages, f...

DNA damage, arising from endogenous metabolism or exposure to environmental agents, may perturb the transmission of genetic information by blocking DNA replication and/or inducing mutations, which contribute to the development of cancer and likely other human diseases. Hydroxyl radical attack on the C1', C3' and C4' of 2-deoxyribose can give rise to epimeric 2-deoxyribose lesions, for which the...

The existence of N-formylated sugars in the O-antigens of Gram-negative bacteria has been known since the middle 1980s, but only recently have the biosynthetic pathways for their production been reported. In these pathways, glucose-1-phosphate is first activated by attachment to a dTMP moiety. This step is followed by a dehydration reaction and an amination. The last step in these pathways is c...

The fidelity and progression of DNA synthesis is critically dependent on the correct balance and availability of the deoxynucleoside triphosphate (dNTP) precursors for the polymerases involved in DNA replication and repair. Because folate-derived one-carbon groups are essential for the de novo synthesis of both purines and pyrimidines, the purpose of this study was to determine the effect of fo...