The DEAD-box RNA helicases RhlE2 is a global regulator ofPseudomonas aeruginosalifestyle and pathogenesis

AbstractThe RhlE DEAD-box RNA helicase protein family is widespread among Proteobacteria, but it is the least understood due to the lack of a clear biological function. Here, we study the two RhlE homologs present in the opportunistic pathogenPseudomonas aeruginosa. RhlE1 and RhlE2 diverged duringP. aeruginosaevolution; our data indicate that this resulted in a non-redundant biological role, a distinct molecular action and an enzymatic activity differentially stimulated by RNA. Whereas RhlE1 is specifically necessary for bacteria growth in cold, we show that RhlE2 acts as global post-transcriptional regulator, affecting the level of hundreds of cellular transcripts and multiple functionalities indispensable not only forP. aeruginosaenvironmental adaptation, but also for its virulence. The global action of RhlE2 relies on a unique C-terminal extension, which establishes an RNA-dependent interaction with the RNase E endonuclease and the cellular RNA degradation machinery.