Structure properties and dephosphorylation activity of phosphatase RsbU from Vibrio brasiliensis

In the stress signal transduction pathway, the regulator of sigma B protein T (RsbT) can be activated and phosphorylated under environmental stress. However, how it transmits its signal to the downstream signaling protein regulator of sigma B protein U (RsbU) remains unknown. To prevent and control Vibrio infection and clarify the tolerance mechanism and stress signal transduction of Vibrio under environmental stress, using Vibrio brasiliensis as a model strain, its physicochemical properties, functional sites and interaction mechanism were analyzed using bioinformatics software, the interaction mode of RsbU and RsbT was explored, and the enzymatic properties of RsbU were investigated. The results showed that the expression vectors were successfully constructed, and the RsbU proteins were purified. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the molecular weight of these proteins was in accordance with the expected size. RsbU was essentially a 2C protein phosphatase (PP2C), and the results obtained from Sring, a database for protein interactions network analysis, showed that the interaction scores between RsbU and RsbT were more than 0.98. Enzymatic properties results showed that the RsbU was a Ser/Thr phosphatase with a weak dephosphorylation ability that mainly acted in the prephase stage, and did not carry a phosphate group itself. Therefore, it was inferred that the N-terminal of RsbU mainly bound to RsbT to receive signals, while the C-terminal of RsbU bound to RsbT weakly for dephosphorylation, thus completing the upstream and downstream stress signaling.