Regulatory Effect of DNA Topoisomerase I on T3SS Activity, Antibiotic Susceptibility and Quorum- Sensing-Independent Pyocyanin Synthesis in Pseudomonas aeruginosa

Abstract

Topoisomerases are required for alleviating supercoiling of DNA during transcription and replication. Recent evidence suggests that supercoiling of bacterial DNA can affect bacterial pathogenicity. To understand the potential regulatory role of a topoisomerase I (TopA) in Pseudomonas aeruginosa, we investigated a previously isolated topA mutation using genetic approaches. We here report the effects of the altered topoisomerase in P. aeruginosa on type III secretion system, antibiotic susceptibility, biofilm initiation, and pyocyanin production. We found that topA was essential in P. aeruginosa, but a transposon mutant lacking the 13 amino acid residues at the C-terminal of the TopA and a mutant, named topA-RM, in which topA was split into three fragments were viable. The reduced T3SS expression in topA-RM seemed to be directly related to TopA functionality, but not to DNA supercoiling. The drastically increased pyocyanin production in the mutant was a result of up-regulation of the pyocyanin related genes, and the regulation was mediated through the transcriptional regulator PrtN, which is known to regulate bacteriocin. The well-established regulatory pathway, quorum sensing, was unexpectedly not involved in the increased pyocyanin synthesis. Our results demonstrated the unique roles of TopA in T3SS activity, antibiotic susceptibility, initial biofilm formation, and secondary metabolite production, and revealed previously unknown regulatory pathways.

Antibacterial activity of a DNA topoisomerase I inhibitor versus fluoroquinolones in Streptococcus pneumoniae

“…Moreover, SCN was the compound causing the highest reduction in the viability and adhesion of sessile bacteria, decreasing biofilm thickness and the size of monolayers. Recent studies in Pseudomonas aeruginosa support the relationship established in our study between TopoI and the formation of biofilms [62]. It has also been described the anti-biofilm effect of other alkaloid, based on the inhibition of effective adhesion and growth of bacteria forming the biofilm [63].…”

Novel Insight of Transcription Factor PtrA on Pathogenicity and Carbapenems Resistance in Pseudomonas aeruginosa

“…50 Previous studies have shown that the QS system of PA is often directly regulated by transcriptional regulators. [51][52][53] According to our result, we speculate that PtrA may directly act on the QS system of PA. However, which system PtrA mainly acts on and how it affects the interaction of each system needs to be further explored in our subsequent research.…”

Peptide Dimerization Effect on Bacterial Topoisomerases Activity

“…As bacterial topoisomerase IA is essential for cellular viability of a number of important bacterial pathogens, this enzyme also represents a valid target for novel antibiotics aimed at overcoming antimicrobial resistance [6]. Again, CM3 was the best inhibitor (Table 2).…”