Evolutionary Rewiring Of The Antitoxin MqsA Regulatory Circuit In Pseudomonas Fluorescens

The mqsRA operon encodes a toxin-antitoxin pair that was characterized to participate in biofilm and persister cell formation in Escherichia coli.Notably,the antitoxin MqsA possesses a C-terminal DNA-binding domain recognizing the[5'-AACCT?N?_2-4AGGTT-3']motif and acts as a transcriptional regulator controlling multiple genes including the general stress response regulator RpoS.However,it is still unknown how the transcriptional circuits of MqsA homologs have changed in bacteria over evolutionary time.Here,we found mqsA in Pseudomonas fluorescens?PfmqsA?is acquired through horizontal gene transfer and binds to a slightly different motif[5'-TACCCT?N?₃AGGGTA-3'],which exists upstream of the PfmqsRA operon.Interestingly,an adjacent GntR-type transcriptional regulator,which was termed agtR,is under negative control of PfMqsA.It was further demonstrated that PfMqsA reduces production of biofilm components through agtR,which directly regulates the pag and fap operons involved in synthesis of extracellular polymeric substances.Moreover,through quantitative proteomics analysis,we showed AgtR is a highly pleiotropic regulator that influences up to 252 genes related to diverse processes including chemotaxis,oxidative phosphorylation,and carbon and nitrogen metabolism.Taken together,our findings suggest the rewired regulatory circuit of PfMqsA influences diverse physiological aspects of P.fluorescens via the newly characterized agtR.