title: Background Mutational Features of the Radiation-Resistant Bacterium Deinococcus radiodurans.
abstract: Deinococcus bacteria are extremely resistant to radiation, oxidation, and desiccation. Resilience to these factors has been suggested to be due to enhanced damage prevention and repair mechanisms, as well as highly efficient antioxidant protection systems. Here, using mutation-accumulation experiments, we find that the GC-rich Deinococcus radiodurans has an overall background genomic mutation rate similar to that of E. coli, but differs in mutation spectrum, with the A/T to G/C mutation rate (based on a total count of 88 A:T → G:C transitions and 82 A:T → C:G transversions) per site per generation higher than that in the other direction (based on a total count of 157 G:C → A:T transitions and 33 G:C → T:A transversions). We propose that this unique spectrum is shaped mainly by the abundant uracil DNA glycosylases reducing G:C → A:T transitions, adenine methylation elevating A:T → C:G transversions, and absence of cytosine methylation decreasing G:C → A:T transitions. As opposed to the greater than 100× elevation of the mutation rate in MMR(-) (DNA Mismatch Repair deficient) strains of most other organisms, MMR(-) D. radiodurans only exhibits a 4-fold elevation, raising the possibility that other DNA repair mechanisms compensate for a relatively low-efficiency DNA MMR pathway. As D. radiodurans has plentiful insertion sequence (IS) elements in the genome and the activities of IS elements are rarely directly explored, we also estimated the insertion (transposition) rate of the IS elements to be 2.50 × 10(-3) per genome per generation in the wild-type strain; knocking out MMR did not elevate the IS element insertion rate in this organism.
authors.affiliation: Department of Biology, Indiana University, Bloomington longhongan@gmail.com.
authors.forename: Hongan
authors.initials: H
authors.lastname: Long
authors.affiliation: Department of Biology, Hacettepe University, Ankara, Turkey.
authors.forename: Sibel
authors.initials: S
authors.lastname: Kucukyildirim
authors.affiliation: Department of Biology, Indiana University, Bloomington.
authors.forename: Way
authors.initials: W
authors.lastname: Sung
authors.affiliation: Department of Biology, Indiana University, Bloomington.
authors.forename: Emily
authors.initials: E
authors.lastname: Williams
authors.affiliation: School of Informatics and Computing, Indiana University, Bloomington.
authors.forename: Heewook
authors.initials: H
authors.lastname: Lee
authors.affiliation: Department of Biology, Indiana University, Bloomington.
authors.forename: Matthew
authors.initials: M
authors.lastname: Ackerman
authors.affiliation: Department of Biology, Indiana University, Bloomington National Center for Genome Analysis Support, Indiana University, Bloomington.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Doak
authors.affiliation: School of Informatics and Computing, Indiana University, Bloomington.
authors.forename: Haixu
authors.initials: H
authors.lastname: Tang
authors.affiliation: Department of Biology, Indiana University, Bloomington.
authors.forename: Michael
authors.initials: M
authors.lastname: Lynch
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D004249:DNA Damage; D019175:DNA Methylation; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics*; D034301:Deinococcus / Q000201:enzymology / Q000235:genetics*; D005798:Genes, Bacterial; D040961:Genetic Drift; D016254:Mutagenesis, Insertional; D059645:Mutation Rate; D010957:Plasmids / Q000235:genetics; D017354:Point Mutation; D011836:Radiation Tolerance; D051981:Uracil-DNA Glycosidase / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D051981:Uracil-DNA Glycosidase
keywords: DNA mismatch repair; Deinococcus radiodurans; mutation accumulation; mutation rate; mutation spectrum