Mutations induced by methylene blue plus light in single-stranded M13mp2.

AUTOR(ES)

McBride, T J

RESUMO

Reactive oxygen species are generated by a variety of cellular processes. These endogenously generated, reactive intermediates produce a multiplicity of DNA alterations and mutations and have been implicated in the pathogenesis of several human diseases. We report here that treatment of single-stranded M13mp2 bacteriophage DNA with methylene blue and white light generates increased levels of 8-hydroxydeoxyguanosine and that mutagenesis is both highly specific and dependent on the SOS response. Lesions produced block the progression of DNA synthesis one base preceding template guanines. In SOS-induced Escherichia coli, 97% of all methylene blue-induced mutations in the lacZ alpha gene of M13mp2 DNA are single-base substitutions opposite template guanines. The most frequent mutations are G----C transversions. The G----T transversions expected from the presence of 8-hydroxydeoxyguanosine in the template strand occur, but at a lower frequency. Sequence data together with SOS dependency and the presence of replication blockage demonstrate that while 8-hydroxydeoxyguanosine may serve as an important marker to monitor oxygen-induced DNA damage in humans, it does not account for either the observed blockage to replication or the mutagenesis by methylene blue plus light in SOS-induced E. coli. Instead, an as yet unidentified lesion generated by active oxygen species is a more potent mutagenic event.

Documentos Relacionados

• A short primer for sequencing DNA cloned in the single-stranded phage vector M13mp2.
• Specificity of ionizing radiation-induced mutagenesis in the lac region of single-stranded phage M13 mp10 DNA.
• Conformations of the Single-Stranded DNA of Bacteriophage M13*
• Single-stranded M13 DNA: use as a cloning vector.
• Different base per unit length ratios exist in single-stranded RNA and single-stranded DNA.