UVM, an ultraviolet-inducible recA-independent mutagenic phenomenon in Escherichia coli

Vaseem A. Palejwala, Gagan A. Pandya, Opinder S. Bhanot, Jerome J. Solomon, Holly S. Murphy, Paul M. Dunman, M. Zafri Humayun

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24 Scopus citations


Most mutagenic DNA lesions are noninstructive in the sense that template instruction is either missing or inaccessible during DNA replication, leading to replication arrest. According to the SOS hypothesis, arrested replication induces the expression of SOS factors that force replication past stalled sites at the cost of mutagenesis. We have recently shown that prior UV irradiation of ΔrecA cells, in which the SOS pathway does not function, enhances mutagenesis at an ethenocytosine residue borne on a circular gapped duplex DNA vector, indicating the existence of an SOS-independent inducible mutagenic phenomenon termed UVM (UV modulation of mutagenesis). In the previous experiments, mutation fixation was expected to occur during gap- filling DNA synthesis. To test whether UVM is observable during normal replication by DNA polymerase III, we have examined mutagenesis at an εC residue borne on M13 single-stranded DNA. By analyzing mutation frequency and specificity using a multiplex sequence assay, we now show that UVM is observable in UV-irradiated recA+, and in ΔrecA cells. These data indicate that UV irradiation induces a previously unrecognized mutagenic mechanism in Escherichia coli, and that this mechanism is manifested during gap-filling DNA synthesis as well as during normal DNA replication.

Original languageAmerican English
Pages (from-to)27433-27440
Number of pages8
JournalJournal of Biological Chemistry
Issue number44
StatePublished - Nov 4 1994

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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