The antitoxin MqsA homologue in Pseudomonas fluorescens 2P24 has a rewired regulatory circuit through evolution

Abstract

Summary 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 that recognizes 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 unknown how the transcriptional circuits of MqsA homologues 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 pga and fap operons involved in the 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 2P24 via the newly characterized AgtR.

An intrinsic mechanism for coordinated production of the contact-dependent and contact-independent weapon systems in a soil bacterium

“…EMSA was performed as previously described [39]. The spell-out FAM-labeled probes of the 50-bp promoter region of the HSAF biosynthesis operon [21] were synthesized by GENEWIZ…”

The Regulator PltZ Regulates a Putative ABC Transporter System PltIJKNOP of Pseudomonas aeruginosa ATCC 27853 in Response to the Antimicrobial 2,4-Diacetylphloroglucinol

“…The E. coli S17-1 strain was used for conjugation. E. coli was grown at 37 • C at 220 rpm in Luria-Bertani (LB) broth or agar plates, and P. aeruginosa and its derivatives were grown at 37 • C at 220 rpm in LB or King's B (KB) medium (Wang et al, 2019). When required, the growth medium was supplemented with ampicillin (50 mg/L), kanamycin sulfate (50 mg/L), gentamicin (30 mg/L), sucrose (10%, m/v), and 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal, 40 mg/L).…”

“…The protein expression and purification of PltZ were performed as previously described (Wang et al, 2019). Briefly, the pltZ gene from P. aeruginosa ATCC 27853 was cloned into the pET-28b-derived vector and transformed into the E. coli BL21 (DE3) strain.…”

Expression of Type II Toxin/Antitoxin systems and ClpP protease of Methicillin-Resistant Staphylococcus aureus under stress condition

“…The TA system, which typically comprises a bicistronic operon encoding a stable protein 'toxin' and a labile protein 'antitoxin', have received much attention because of their vital roles in bacterial physiology [5]. As yet, six types of TA systems have been identified based on their mechanism of action and their nature of the antitoxin (RNA or protein), while the toxin is in all of them a protein [6].…”

“…TA systems may involve stress response by shifting to dormant state which permits cells to cope with stress conditions [5]. Unfavorable conditions such as starvation, antibiotic stresses and heat shock, resulting in degradation of unstable antitoxin, and the imbalance between toxin and antitoxin, lead to toxin interferes with vital cellular processes such as replication, transcription, translation and cell wall synthesis [4,7].…”