Dataset Information

The P-Type ATPase PA1429 Regulates Quorum-Sensing Systems and Bacterial Virulence.

ABSTRACT: Pseudomonas aeruginosa is becoming an increasingly prevalent pathogen, capable of causing numerous life threatening infections in immunocompromised patients. The three hierarchically arranged quorum sensing (QS) systems, namely las, rhl, and pqs play key roles in coordinating virulence expression in P. aeruginosa. However, the regulatory mechanisms of the pqs system have not been fully elucidated. To identify new genes involved in synthesis of the Pseudomonas quinolone signal (PQS), a transposon mutagenesis library was constructed. PA1429 was found to inhibit PQS biosynthesis. The PA1429 deletion mutant also exhibited increased bacterial motility, biofilm formation, and virulence in a mouse model of acute lung infection. Interestingly, it also displayed reduced tolerance to oxidative stress. Mutated pqsH in the PA1429 deletion background restored bacterial susceptibility to H₂O₂. In addition, our data showed that PA1429 repressed the expression of las and rhl systems. Overall, these results provide new insights into the complex regulatory networks of quorum-sensing and virulence expression in P. aeruginosa.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC5770612 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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The P-Type ATPase PA1429 Regulates Quorum-Sensing Systems and Bacterial Virulence.

Zhang Yani Y Qin Jing J Tan Boren B Kong Weina W Chen Gukui G Zhang Chao C Liang Haihua H

Frontiers in microbiology 20171207

Pseudomonas aeruginosa is becoming an increasingly prevalent pathogen, capable of causing numerous life threatening infections in immunocompromised patients. The three hierarchically arranged quorum sensing (QS) systems, namely las, rhl, and pqs play key roles in coordinating virulence expression in P. aeruginosa. However, the regulatory mechanisms of the pqs system have not been fully elucidated. To identify new genes involved in synthesis of the Pseudomona ...[more]

PMID: 29375491

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Project description:Acinetobacter baumannii possesses a single divergent luxR/luxRI-type quorum-sensing (QS) locus named abaR/abaI This locus also contains a third gene located between abaR and abaI, which we term abaM, that codes for an uncharacterized member of the RsaM protein family known to regulate N-acylhomoserine lactone (AHL)-dependent QS in other beta- and gammaproteobacteria. Here, we show that disruption of abaM via a T26 insertion in A. baumannii strain AB5075 resulted in increased production of N-(3-hydroxydodecanoyl)-l-homoserine lactone and enhanced surface motility and biofilm formation. In contrast to the wild type and the abaI::T26 mutant, the virulence of the abaM::T26 mutant was completely attenuated in a Galleria mellonella infection model. Transcriptomic analysis of the abaM::T26 mutant revealed that AbaM differentially regulates at least 76 genes, including the csu pilus operon and the acinetin 505 lipopeptide biosynthetic operon, that are involved in surface adherence, biofilm formation and virulence. A comparison of the wild type, abaM::T26 and abaI::T26 transcriptomes, indicates that AbaM regulates ∼21% of the QS regulon including the csu operon. Moreover, the QS genes (abaI and abaR) were among the most upregulated in the abaM::T26 mutant. A. baumannii lux-based abaM reporter gene fusions revealed that abaM expression is positively regulated by QS but negatively autoregulated. Overall, the data presented in this work demonstrates that AbaM plays a central role in regulating A. baumannii QS, virulence, surface motility, and biofilm formation.IMPORTANCE Acinetobacter baumannii is a multiantibiotic-resistant pathogen of global health care importance. Understanding Acinetobacter virulence gene regulation could aid the development of novel anti-infective strategies. In A. baumannii, the abaR and abaI genes that code for the receptor and synthase components of an N-acylhomoserine (AHL) lactone-dependent quorum sensing system (QS) are separated by abaM Here, we show that although mutation of abaM increased AHL production, surface motility, and biofilm development, it resulted in the attenuation of virulence. AbaM was found to control both QS-dependent and QS-independent genes. The significance of this work lies in the identification of AbaM, an RsaM ortholog known to control virulence in plant pathogens, as a modulator of virulence in a human pathogen.

Project description:The main objectives of this work were to investigate the effect of atmospheric cold plasma (ACP) against a range of microbial biofilms commonly implicated in foodborne and healthcare associated human infections and against P. aeruginosa quorum sensing (QS)-regulated virulence factors, such as pyocyanin, elastase (Las B) and biofilm formation capacity post-ACP treatment. The effect of processing factors, namely treatment time and mode of plasma exposure on antimicrobial activity of ACP were also examined. Antibiofilm activity was assessed for E. coli, L. monocytogenes and S. aureus in terms of reduction of culturability and retention of metabolic activity using colony count and XTT assays, respectively. All samples were treated 'inpack' using sealed polypropylene containers with a high voltage dielectric barrier discharge ACP generated at 80 kV for 0, 60, 120 and 300 s and a post treatment storage time of 24 h. According to colony counts, ACP treatment for 60 s reduced populations of E. coli to undetectable levels, whereas 300 s was necessary to significantly reduce populations of L. monocytogenes and S. aureus biofilms. The results obtained from XTT assay indicated possible induction of viable but non culturable state of bacteria. With respect to P. aeruginosa QS-related virulence factors, the production of pyocyanin was significantly inhibited after short treatment times, but reduction of elastase was notable only after 300 s and no reduction in actual biofilm formation was achieved post-ACP treatment. Importantly, reduction of virulence factors was associated with reduction of the cytotoxic effects of the bacterial supernatant on CHO-K1 cells, regardless of mode and duration of treatment. The results of this study point to ACP technology as an effective strategy for inactivation of established biofilms and may play an important role in attenuation of virulence of pathogenic bacteria. Further investigation is warranted to propose direct evidence for the inhibition of QS and mechanisms by which this may occur.

Dataset Information

The P-Type ATPase PA1429 Regulates Quorum-Sensing Systems and Bacterial Virulence.

Publications

The P-Type ATPase PA1429 Regulates Quorum-Sensing Systems and Bacterial Virulence.

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