The Potential of Genetic Transformation as a Mechanism of Bacterial DNA Repair in Acinetobacter Baylyi[/i] Strain ADP1

We are investigating DNA damage response mechanisms in the Gram-negative bacterial genus, [i]Acinetobacter[/i]. One member of this genus, [i]A. baylyi[/i] strain ADP1, has a truncated [i]umuDC[/i] DNA damage response operon that makes it unable to respond to DNA damage like other bacteria. However, ADP1 can survive higher levels of DNA damage than many bacteria, such as [i]Escherichia coli[/i], that possess a well-studied DNA damage response. ADP1 cells can also develop natural competence in early log phase to take up DNA via transformation. Our hypothesis is that without [i]umuDC[/i] gene function, natural transformation is used as a source of undamaged DNA to help repair DNA damage in ADP1 and possibly other [i]Acinetobacter[/i]. We conducted a survey of diverse members of [i]Acinetobacter[/i] to: (i) measure various strains’ ability to survive DNA damage (from UV light), and (ii) determine whether each strain could develop natural competence to take up plasmid DNA. In the ten [i]Acinetobacter[/i] strains examined, survival on nutrient agar after 150 J/m2 of UV exposure ranged from three orders of magnitude less than ADP1 to the same survival levels as ADP1. All [i]Acinetobacter[/i] strains examined did not develop natural competence under conditions where the ADP1 strain, consistent with previous reports, did develop natural competence. These data, once collected for all 21 strains of [i]Acinetobacter[/i] andcompared with the presence or absence of intact [i]umuDC[/i] operons in these strains, will help determine whether the extent to which [i]Acinetobacter[/i] survival after DNA damage exposure is affected by their ability to perform natural transformation