The Ferredoxin-Like Protein FerR Regulates PrbP Activity in Liberibacter asiaticus

The rapid spread and aggressive progression of huanglongbing (HLB) in the major citrus-producing areas have raised global recognition of and vigilance to this disease. As a result, the causative agent,Liberibacter asiaticus , has been investigated from various perspectives. However, gene expression regulatory mechanisms that are important for the survival and persistence of this intracellular pathogen remain largely unexplored. PrbP is a transcriptional accessory protein important forL. asiaticus survival in the plant host. In this study, we investigated the interactions between PrbP inL. asiaticus (PrbPLas ) and a ferredoxin-like protein (FerR) inL. asiaticus , FerRLas . We show that the presence of FerR stabilizes and augments the activity of PrbPLas . In addition, we demonstrate that the expression offerR is induced by increases in osmolarity inLiberibacter crescens . Altogether, these results suggest that FerRLas and PrbPLas may play important roles in the regulation of gene expression in response to changing environmental signals duringL. asiaticus infection in the citrus host.