Active Transposition of Insertion Sequences by Oxidative Stress in Deinococcus geothermalis

Abstract

Radiation-resistant bacterium Deinococcus geothermalis has a total of 73 insertion sequences (ISs) in genomes, and some of them are actively transposed to other loci with replicative mode due to oxidative stress of hydrogen peroxide treatment. Here, we detected two transposition events in wild-type (WT) strain and LysR family member gene disrupted strain (dgeo_2840). Similar to our previous report (Lee et al., 2019), phytoene desaturase (dgeo_0524), a key enzyme of carotenoid biosynthesis, was disrupted by the integration of IS element, thereby detected a single phenotypically non-pigmented colony in each WT and dgeo_2840 strain. Two separate types of IS element have been integrated into non-pigmented clones: ISDge11 for WT and ISDge6 for dgeo_2840 strain. Surprisingly, dgeo_2840 mutant strain revealed higher resistance to oxidative stress than WT strain at late exponential growth phase. From the qRT-PCR analysis, OxyR (dgeo_1888) was highly up-regulated to 30-fold by oxidative stress through hydrogen peroxide treatment in both WT and dgeo_2840 mutant strains. However, the oxidative stress response enzyme, catalase or superoxide dismutase, was not significantly induced by overexpressed OxyR. Thus, a putative LysR family regulator Dgeo_2840 controlled the expression of ISDge6 type transposase and the induction of OxyR under oxidative condition. There is LysR family DNA-binding protein dependent active transposition of specific type IS and the up-regulated OxyR has not positively controlled ROS scavenger enzymes in D. geothermalis.

Coexistence of SOS-Dependent and SOS-Independent Regulation of DNA Repair Genes in Radiation-Resistant Deinococcus Bacteria

“…Finally, it is important to mention that induced mutagenesis via transposition of insertion sequence (IS) elements has also been described in two Deinococcus species. In D. radiodurans and D. geothermalis, which lack TLS polymerases, transposition of certain IS elements is induced after exposure to radiation or oxidative stress [65][66][67]. Other Deinococcus species, including D. deserti [4], also contain IS elements, but it is currently unknown if transposition of one or more of these ISs is stimulated after stress exposure.…”

Genome Plasticity by Insertion Sequences Learned From a Case of Radiation-Resistant Bacterium Deinococcus geothermalis

“…Our previous studies have found that multi-copy IS elements, IS Dge5 , IS Dge6 , IS Dge7 , and IS Dge11 members, used a replicative transposition action mode and their movement was actively triggered by oxidative stress resulting in enhancing the copy number through active transposition. 17 , 18 There are 6 single IS members (IS Dge1 , IS Dge8 , IS Dge10 , IS Dge14 , IS Dge15 , and IS Dge17 ). Interestingly, all 7 IS copies of IS Dge13 type are found in plasmid pDGEO02.…”

“…Deletion of the LysR family regulator gene Dgeo_2840 resulted in the transposition of IS Dge6 type IS into carotenoid biosynthesis enzymes through replicative transposition in an oxidative-stress induced manner. 18 Although the genome of a strain of wild-type D. geothermalis already contains 10 copies of IS Dge5 , 5 copies of IS Dge6 , and 4 copies of IS Dge7 , active transposition of their ISs was caused by oxidative stress. In other words, hydrogen peroxide treatment under conditions without specific DNA-binding proteins, Dgeo_0257 and Dgeo_2840, resulted in further gene disruption caused by active transposition of distinct IS element ( Table 2 ).…”

“… 17 In addition, active transposition of IS Dge6 from the LysR family regulator disrupted mutant (Δ dgeo _2840) and IS Dge11 from the wild type by oxidative stress was first reported in our previous work. 18 From these observations, we have motivated the question: Can we look at the earlier genome contents of the bacterium before transposition of ISs in terms of genomic plasticity? Thus, we performed an in silico correction to imagine past events by the recovery of mutation of genomic contents by ISs through the elimination of full-length ISs from the genome sequence of wild-type D. geothermalis DSM11300 T .…”

Frequent Transposition of Multiple Insertion Sequences in Geobacillus kaustophilus HTA426

“…Stress-induced transposition has been reported for several organisms by respective stressors ( Zhang and Saier, 2016 ; Vandecraen et al, 2018 ; Lee et al, 2019 , 2020 ). In G. stearothermophilus CU21, IS 4 and IS 21 members have been reported to achieve transposition during growth inhibition by chloramphenicol exposure ( Xu et al, 1993 ).…”