Abstract
Bacterial genomes contain numerous insertion sequences (ISs) as transposable elements involved in actions such as the sequestration, transmission, mutation and activation of genes that can influence the responsive capacity of the organism to environmental challenges. To date, at least 30 IS families have been identified. In this review, we describe how certain ISs are transposed to carotenoid biosynthesis genes, such as phytoene synthase and phytoene desaturase, when radiation-resistant Deinococcus geothermalis with a redox imbalance and a targeted gene disruption mutation is exposed to oxidative stressors, such as gamma-irradiation, dielectric bilayer discharge plasma and hydrogen peroxide. We also explain the genetic features of IS elements, spontaneous mutation and various stress responses, including nutrient limitation, and physicochemical and oxidative stress, associated with the active transposition of bacterial ISs. Based on the current knowledge, we posit that the redox signalling mechanism inducing IS transposition involves redox sensing and redox switching for the activation of transposase expression and its activity.
Highlights
Since the discovery of insertion sequences (ISs; called IS elements) in the late1960s, the number and diversity of prokaryotic ISs have increased enormously
This is typically mediated by de-repression or by the introduction of a partial or complete promoter located within the IS
We describe how certain ISs are transposed to carotenoid biosynthesis genes, such as phytoene synthase and phytoene desaturase, when radiation-resistant D. geothermalis with redox-imbalance and targeted gene disruption mutations is exposed to oxidative stressors, such as gamma-irradiation, dielectric bilayer discharge plasma and hydrogen peroxide
Summary
Since the discovery of insertion sequences (ISs; called IS elements) in the late. ISs are detected and confirmed by comparative analysis of genome sequences using IS determination platforms, such as ISMapper [7], ISQuest [8], OASIS [9], and especially the pioneering database ISfinder [1]. These computational IS-finding platforms provide an IS framework using basic DNA sequence matching in the border regions of IS elements, such as the terminal inverted repeats (TIRs) and the functionally important transposase (Tpase or Tnp) gene, based on amino acid sequence similarity and conserved motifs, like the DDE-motif [2]. We briefly summarise the current knowledge of IS transposition including the genetic features of IS elements, spontaneous mutation and various stress responses, including nutrient limitation, and physicochemical and oxidative stress, associated with the active transposition of bacterial ISs
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