ABSTRACT
Pseudomonas aeruginosa is an important Gram-negative opportunistic pathogen, which exists in a wide range of environmental settings. People with immunocompromised diseases are often targeted by P. aeruginosa, resulting in hospital-acquired infections, which are difficult to treat due to their growing multidrug resistance. It has been reported that P. aeruginosa showed resistance to nearly all antibiotics. More than 50,000 P. aeruginosa infection cases were reported in the United States each year with approximately 400 deaths. P. aeruginosa infection usually causes acute pulmonary infection which transforms into chronic infection in people with cystic fibrosis (CF), dependent on the expression of different virulence factors. Recently, a two-component system (TCS), histidine kinases LadS and RetS, was discovered in P. aeruginosa, which can inversely modulate type 3 secretion system (T3SS), T6SS, quorum-sensing (QS), and biofilm formation by interfering with GacS activity and was necessary for the transformation of acute to chronic infection. Despite downstream signals being well-described, how LadS and RetS are activated, particularly the molecular mechanisms, remains largely unknown. Here, we attempt to highlight the recent progress in understanding the regulatory mechanisms of LadS and RetS in P. aeruginosa.
