Role of respiratory NADH oxidation in the regulation of Staphylococcus aureus virulence

The success of Staphylococcus aureus as a pathogen is due to its capability of fine-tuning its cellular physiology to meet the challenges presented by diverse environments, which allows it to colonize multiple niches within a single vertebrate host. Elucidating the roles of energy-yielding metabolic pathways could uncover attractive therapeutic strategies and targets. In this work, we seek to determine the effects of disabling NADH-dependent aerobic respiration on the physiology of S. aureus. Differing from many pathogens, S. aureus has two type-2 respiratory NADH dehydrogenases (NDH-2s) but lacks the respiratory ion-pumping NDHs. Here, we show that the NDH-2s, individually or together, are not essential either for respiration or growth. Nevertheless, their absence eliminates biofilm formation, production of α-toxin, and reduces the ability to colonize specific organs in a mouse model of systemic infection. Moreover, we demonstrate that the reason behind these phenotypes is the alteration of the fatty acid metabolism. Importantly, the SaeRS two-component system, which responds to fatty acids regulation, is responsible for the link between NADH-dependent respiration and virulence in S. aureus.