Identification of PNPase and RhlB binding proteins in Deinococcus radiodurans

8-oxo-7,8-dihydroguanine (8-oxoG) is a common RNA oxidation that has been implicated in carcinogenesis, neurodegeneration, and aging. Some? Many? RNA-binding proteins have shown binding preference for 8-oxoG modified RNA; such binding? can protect cells from oxidative stress. To date, the presence of specific 8-oxoG-recognizing proteins is only known in model organisms, but, how these proteins cooperate is still unclear. Here, we use RNA affinity chromatography and mass spectrometry to search for proteins that specifically bind 8-oxoG-modified RNA in Deinococcus radiodurans, an extremophilic bacterium with extraordinary resistance to oxidative stresses. We identified four proteins that selectively bind to oxidized RNA: polynucleotide phosphorylase (DR_2063/PNPase), ATP-dependent DEAD-box RNA helicase (DR_0335/RhlB), ribosomal protein S1 (DR_1983/RpsA), and transcriptional termination factor (DR_1338/Rho). The knockout of PNPase and RhlB in D. radiodurans caused increased sensitivity to hydrogen peroxide and a significant accumulation of 8-oxoG modified RNA. Importantly, PNPase directly interacts with RhlB in D. radiodurans; however, no additional phenotypic effect was observed for the double deletion of pnp and rhlB compared to the individual single deletions. Overall, our findings suggest a role of the PNPase-RhlB complex in targeting 8-oxoG-modified RNAs for rapid degradation and thereby constitutes an important component of D. radiodurans resistance to oxidative stress.