Functional characterization of light sensing LOV1 protein in virulence and lifestyles of Pseudomonas cichorii JBC1

Abstract

Abstract processes. The effects of light, oxygen, or voltage (LOV) and blue light (BL) photosensory proteins on the virulence and pathogenic features of plant bacterial pathogens require further exploration. In this study, we identified LOV protein (Pc-LOV1) from Pseudomonas cichorii JBC1 (PcJBC1) and characterized its function using LOV1-deficient mutant (JBC1Δlov1). The recombinant Pc-LOV1 protein showed absorption peaks at 448, 425, and 475 nm in the dark, which is a typical feature of oxidized flavin chromophores. BL negatively influenced the virulence of PcJBC1 and the virulence of JBC1Δlov1 increased irrespective of BL, indicating that Pc-LOV1 negatively regulates PcJBC1 virulence. Pc-LOV1 and BL positively regulated the biological features relevant to infection processes, such as adhesion to the plant surface and biofilm formation. In contrast, swarming motility, exopolysaccharide and siderophore production were negatively controlled. Gene expression and in silico analysis of the interacting proteins supported the modulation of bacterial features. Overall, our results suggest that the LOV photosensory system plays crucial roles in the adaptive responses and pathogenicity of the bacterial pathogen PcJBC1. The roles of other photoreceptors, sensing of other light wavelengths, and signal networking require further investigation.