Rowan University Glassboro, New Jersey, United States
Abstract Text: Agrobacterium tumefaciens, the causative agent of crown gall disease, is a major pathogen resulting in extensive economic loss in many crop species. Host plant interaction and plant cell transformation is a multi-step process regulated by both bacterium-intrinsic and environmental factors. Among bacterium-intrinsic factors, two-component regulatory systems are known to control important aspects of pathogenesis. For example, the VirA/VirG system transcriptionally activates the vir genes required for T-DNA transfer. Using transposon-based mutational analysis, we screened for mutants with increased swimming motility relative to wild-type and swimming-deficient strains. Among identified disrupted loci was the atu0970-atu0971 operon encoding a sensor kinase (Atu0971/FeuQ) and a response regulator (Atu0970/FeuP). Deletion of both components of this predicted two-component system singly and in combination resulted in significant reductions in both biofilm formation and swimming motility. Furthermore, loss of either feuP or feuQ significantly reduced tumor burden in a potato disc tumor assay. RNA-seq analysis and phenotype microarray screening of feuP- or feuQ-deficient strains identified numerous differentially regulated genes and additional phenotypes regulated by this system. Together, these data suggest that the FeuPQ two-component system functions to enable efficient host interactions and plant transformation. Homologues of FeuP and FeuQ are conserved in several members of the Alphaproteobacteria, highlighting the importance of this system in promoting fitness.
