4 research outputs found
Two Component Regulatory Systems and Antibiotic Resistance in Gram-Negative Pathogens
Gram-negative pathogens such as Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa are the leading cause of nosocomial infections throughout the world. One commonality shared among these pathogens is their ubiquitous presence, robust host-colonization and most importantly, resistance to antibiotics. A significant number of two-component systems (TCSs) exist in these pathogens, which are involved in regulation of gene expression in response to environmental signals such as antibiotic exposure. While the development of antimicrobial resistance is a complex phenomenon, it has been shown that TCSs are involved in sensing antibiotics and regulating genes associated with antibiotic resistance. In this review, we aim to interpret current knowledge about the signaling mechanisms of TCSs in these three pathogenic bacteria. We further attempt to answer questions about the role of TCSs in antimicrobial resistance. We will also briefly discuss how specific two-component systems present in K. pneumoniae, A. baumannii, and P. aeruginosa may serve as potential therapeutic targets
Characterization of the Direct Interaction between Hybrid Sensor Kinases PA1611 and RetS That Controls Biofilm Formation and the Type III Secretion System in Pseudomonas aeruginosa
One
of the leading causes of morbidity and mortality in cystic fibrosis
(CF) patients is pulmonary infection with Pseudomonas
aeruginosa, and the pathophysiology of pulmonary infection
in CF is affected by the lifestyle of this micro-organism. RetS-GacS/A-RsmA
is a key regulatory pathway in P. aeruginosa that determines the bacterium’s lifestyle choice. Previously,
we identified PA1611, a hybrid sensor kinase, as a new player in this
pathway that interacts with RetS and influences biofilm formation
and type III secretion system. In this study, we explored the structural
and mechanistic basis of the interaction between PA1611 and RetS.
We identified the amino acid residues critical for PA1611–RetS
interactions by molecular modeling. These residues were then targeted
for site-directed mutagenesis. Amino acid substitutions were carried
out at seven key positions in PA1611 and at six corresponding key
positions in RetS. The influence of such substitutions in PA1611 on
the interaction was analyzed by bacterial two-hybrid assays. We carried
out functional analysis of these mutants in P. aeruginosa for their effect on specific phenotypes. Two residues, F269 and
E276, located within the histidine kinase A and histidine kinase-like
ATPase domains of PA1611 were found to play crucial roles in the PA1611–RetS
interaction and had profound effects on phenotypes. Corresponding
mutations in RetS demonstrated similar results. We further confirmed
that these mutations in PA1611 function through the GacS/GacA-RsmY/Z
signaling pathway. Collectively, our findings provide a noncognate
sensor kinase direct interaction model for a signaling pathway, key
for lifestyle selection in P. aeruginosa, and targeting such interaction may serve as a novel way of controlling
infections with P. aeruginosa