Fig 3.

The predicted A. baumannii TLS DNA polymerases and other DNA damage response genes are induced by DNA damage and regulated by RecA. (A) Expression of putative DNA polymerase V genes. All umuD and umuC loci are upregulated upon MMS, ciprofloxacin, or UV light treatment in the recA⁺ strain. In the recA::Km strain, most genes have no change in expression, which is denoted as a fold change of 1. We also observed increased expression for some of the genes, though it was lower than that in the recA⁺ strain. (B) Expression of other DNA damage response genes. The three DNA-damaging conditions examined resulted in upregulation of recA and uvrA in the recA⁺ strain. uvrA is regulated by RecA, as shown by its high expression in the recA⁺ strain. Notably, a large increase in recA expression is seen in the UV-treated recA::Km strain. There is no increase in expression of dinB or the 16S rRNA control in either strain. The recA⁺ and recA::Km strains were treated with 25 mM and 1.5 mM MMS, respectively, for 1 h; 6 μg ml⁻¹ and 1 μg ml⁻¹ of ciprofloxacin, respectively, for 1 h; and 270 J m⁻² and 5 J m⁻² of UV light, respectively. Semiquantitative RT-PCR was performed on total RNA purified from treated and untreated cultures as described in the Fig. 2 legend and Materials and Methods. Locus tags from the A. baumannii ATCC 17978 genome (“A1S_” is not included before the numbers) are included as part of the gene names. Data from a representative experiment are shown.