A chemical genetics analysis of the roles of bypass polymerase DinB and DNA repair protein AlkB in processing N2-alkylguanine lesions in vivo.

DinB, the E. coli translesion synthesis polymerase, has been shown to bypass several N2-alkylguanine adducts in vitro, including N2-furfurylguanine, the structural analog of the DNA adduct formed by the antibacterial agent nitrofurazone. Recently, it was demonstrated that the Fe(II)- and α-ketoglutarate-dependent dioxygenase AlkB, a DNA repair enzyme, can dealkylate in vitro a series of N2-alkyguanines, including N2-furfurylguanine.

Removal of N-alkyl modifications from N(2)-alkylguanine and N(4)-alkylcytosine in DNA by the adaptive response protein AlkB.

The AlkB enzyme is an Fe(II)- and α-ketoglutarate-dependent dioxygenase that repairs DNA alkyl lesions by a direct reversal of damage mechanism as part of the adaptive response in E. coli. The reported substrate scope of AlkB includes simple DNA alkyl adducts, such as 1-methyladenine, 3-methylcytosine, 3-ethylcytosine, 1-methylguanine, 3-methylthymine, and N(6)-methyladenine, as well as more complex DNA adducts, such as 1,N(6)-ethenoadenine, 3,N(4)-ethenocytosine, and 1,N(6)-ethanoadenine.

Chemical biology of mutagenesis and DNA repair: cellular responses to DNA alkylation.

The reaction of DNA-damaging agents with the genome results in a plethora of lesions, commonly referred to as adducts. Adducts may cause DNA to mutate, they may represent the chemical precursors of lethal events and they can disrupt expression of genes. Determination of which adduct is responsible for each of these biological endpoints is difficult, but this task has been accomplished for some carcinogenic DNA-damaging agents.

Efficient replication bypass of size-expanded DNA base pairs in bacterial cells.

Supersize me! Size-expanded DNA bases (xDNA) are able to encode natural DNA sequences in replication. In vitro experiments with a DNA polymerase show nucleotide incorporation opposite the xDNA bases with correct pairing. In vivo experiments using E.