NorA, HmpX, and NorB Cooperate to Reduce NO Toxicity during Denitrification and Plant Pathogenesis in Ralstonia solanacearum

Abstract

The soilborne plant pathogen Ralstonia solanacearum ( Rs ) causes bacterial wilt, a serious and widespread threat to global food security. Rs is metabolically adapted to low-oxygen conditions, using denitrifying respiration to survive in the host and cause disease. However, bacterial denitrification and host defenses generate nitric oxide (NO), which is toxic and also alters signaling pathways in both the pathogen and its plant hosts. Rs mitigates NO with a trio of mechanistically distinct proteins: NO-reductase (NorB), predicted iron-binding (NorA), and oxidoreductase (HmpX).