Dynamic and intricate regulation by the Csr sRNAs in the Arctic Pseudoalteromonas fuliginea.

The Csr (Carbon Storage Regulator) system is pivotal in controlling various cellular functions in most bacteria, primarily through the CsrA protein and its antagonistic sRNAs. However, riboregulatory networks are less explored in non-model organisms, particularly those in extreme environments. In this study, we discovered two new sRNAs of the Csr system, Pf2 and Pf3, in the Arctic bacterium Pseudoalteromonas fuliginea BSW20308, along with the previously known Pf1. By studying the impact of these Pf sRNAs on CsrA targetomes and physiological processes, we found a significant influence on various cellular functions and a collective effect on the interaction dynamics between CsrA and RNAs. Furthermore, we identified additional sRNAs that can interact with CsrA and mRNAs. Overall, our results emphasize the growing influence of the Csr system on cellular physiology through intricate sRNA regulation of CsrA, revealing riboregulatory network complexity and significance in non-model organisms.