Morehead State University
Diverse Capacities for DNA Damage Survival Across the Genus Acinetobacter
Institution
Morehead State University
Faculty Advisor/ Mentor
Janelle Hare
Abstract
Many bacteria use an inducible SOS response system to respond to DNA damage in which the umuDC operon is required for trans-lesion DNA synthesis after DNA damage. In the naturally competent Gram-negative bacterium, Acinetobacter baylyi strain ADP1, the umuD gene possesses an extended 5’ region, and a fragmented umuC gene. We surveyed diverse Acinetobacter species for their umuDC operon presence and configuration and survival after UV exposure. Surprisingly, conservation of these DNA damage-related properties along phylogenetic lines was present as measured by multiple assays. Cloning of the umuDC operon from diverse Acinetobacter strains revealed that all twenty Acinetobacter strains analyzed had a umuDAb-like gene with 79-100% nucleotide identity over ~500 bp to the umuD of ADP1, including its extended 5’ region. However, two forms of the extra-long umuD allele were present in Acinetobacter strains: one form in the closely related Acb complex strains, with the other form present in all other strains. Like ADP1, no strain contained an intact umuC gene, consistent with the inability of these strains to conduct SOS mutagenesis after UV-C exposure. Survival of seventeen Acinetobacter strains after UV-C exposure ranged from five orders of magnitude less than ADP1 to 150% of the survival levels seen in ADP1 (the aptly named A. radioresistens), with this variation also clustered along phylogenetic groups within the genus. The Acb complex strains and the hemolytic strains had a lower survival than non-Acb or non-hemolytic strains, as did strains of human origin vs. strains originally isolated from environmental sources.
Diverse Capacities for DNA Damage Survival Across the Genus Acinetobacter
Many bacteria use an inducible SOS response system to respond to DNA damage in which the umuDC operon is required for trans-lesion DNA synthesis after DNA damage. In the naturally competent Gram-negative bacterium, Acinetobacter baylyi strain ADP1, the umuD gene possesses an extended 5’ region, and a fragmented umuC gene. We surveyed diverse Acinetobacter species for their umuDC operon presence and configuration and survival after UV exposure. Surprisingly, conservation of these DNA damage-related properties along phylogenetic lines was present as measured by multiple assays. Cloning of the umuDC operon from diverse Acinetobacter strains revealed that all twenty Acinetobacter strains analyzed had a umuDAb-like gene with 79-100% nucleotide identity over ~500 bp to the umuD of ADP1, including its extended 5’ region. However, two forms of the extra-long umuD allele were present in Acinetobacter strains: one form in the closely related Acb complex strains, with the other form present in all other strains. Like ADP1, no strain contained an intact umuC gene, consistent with the inability of these strains to conduct SOS mutagenesis after UV-C exposure. Survival of seventeen Acinetobacter strains after UV-C exposure ranged from five orders of magnitude less than ADP1 to 150% of the survival levels seen in ADP1 (the aptly named A. radioresistens), with this variation also clustered along phylogenetic groups within the genus. The Acb complex strains and the hemolytic strains had a lower survival than non-Acb or non-hemolytic strains, as did strains of human origin vs. strains originally isolated from environmental sources.