DEAD box RNA helicases protect Antarctic Pseudomonas syringae Lz4W against oxidative stress

DEAD box RNA helicases are involved in important cellular processes like RNA metabolism (Processing and Degradation), ribosome biogenesis and translation. Besides being crucial to the formation of cold adapted degradosomes, RNA helicases have been implicated in structural rearrangement of RNA, implying a role in alleviation of RNA secondary structure stabilization at low temperature. This study depicts the results of experiments on protective role played by DEAD box RNA helicases against nucleic acid damaging agents. RNA helicase mutants ΔrhlE, ΔsrmB, ΔcsdA, ΔdbpA and ΔrhlB cells were exposed to various DNA damaging agents (UV, Paraquat, Mitomycin C, Hydroxyurea and Hydrogen peroxide) and assessed for sensitivity to them. Our results illustrate that ∆csdA displayed sensitivity to paraquat (that causes oxidative damage) and UV radiation induced DNA damage. On the other hand, ∆srmB displays sensitivity to hydroxyurea that causes damage to the replication forks (RFs) by inhibiting ribonucleotide reductase and depleting the dNTP pool of cells. However, all five RNA helicase mutants were resistant to H₂O₂ mediated oxidative stress and mitomycin C induced DNA cross-links.