Identification and Characterization of the HicAB Toxin-Antitoxin System in the Opportunistic Pathogen Pseudomonas aeruginosa

Li, Gang; Shen, Mengyu; Lu, Shuguang; Le, Shuai; Tan, Yinling; Wang, Jing; Zhao, Xia; Shen, Wei; Guo, Keke; Yang, Yuhui; Zhu, Huajian; Rao, Xiancai; Hu, Fuquan; Li, Ming

doi:10.3390/toxins8040113

Cited by 43 publications

(43 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To assess the effects of gyrase inhibition in vivo , constructs expressing either PaParE or PaParD were transformed into E. coli cells. In these experiments, an E. coli host was chosen rather than Pa cells to minimize confounding effects resulting from endogenous antitoxin expression, a standard practice in studies of TA systems (Gupta et al, ; Li et al, ; Li et al, ). PaParE or PaParD expression was induced by the addition of 0.02% or 0.2% arabinose (to titrate the expression levels) and monitored for growth by turbidity as well as for viability based on colony‐forming units (CFU) (Fig.…”

Section: Resultsmentioning

confidence: 99%

The toxin from a ParDE toxin‐antitoxin system found inPseudomonas aeruginosaoffers protection to cells challenged with anti‐gyrase antibiotics

Muthuramalingam

White

Murphy

et al. 2018

Molecular Microbiology

View full text Add to dashboard Cite

Summary Toxin‐antitoxin systems are mediators of diverse activities in bacterial physiology. For the ParE‐type toxins, their reported role of gyrase inhibition utilized during plasmid‐segregation killing indicates they are toxic. However, their location throughout chromosomes leads to questions about function, including potential non‐toxic outcomes. The current study has characterized a ParDE system from the opportunistic human pathogen Pseudomonas aeruginosa (Pa). We identified a protective function for this ParE toxin, PaParE, against effects of quinolone and other antibiotics. However, higher concentrations of PaParE are themselves toxic to cells, indicating the phenotypic outcome can vary based on its concentration. Our assays confirmed PaParE inhibition of gyrase‐mediated supercoiling of DNA with an IC50 value in the low micromolar range, a species‐specificity that resulted in more efficacious inhibition of Escherichia coli derived gyrase versus Pa gyrase, and overexpression in the absence of antitoxin yielded an expected filamentous morphology with multi‐foci nucleic acid material. Additional data revealed that the PaParE toxin is monomeric and interacts with dimeric PaParD antitoxin with a KD in the lower picomolar range, yielding a heterotetramer. This work provides novel insights into chromosome‐encoded ParE function, whereby its expression can impart partial protection to cultures from selected antibiotics.

show abstract

Section: Resultsmentioning

confidence: 99%

The toxin from a ParDE toxin‐antitoxin system found inPseudomonas aeruginosaoffers protection to cells challenged with anti‐gyrase antibiotics

Muthuramalingam

White

Murphy

et al. 2018

Molecular Microbiology

View full text Add to dashboard Cite

show abstract

“…These proteins may contribute to the survival and adaptation of pp3 and/or PA1 in its natural environment. The pp3 cluster also contains a locus comprising gene PA1S_06925 ( hicA ) and PA1S_06920 ( hicB ), which have been proven to encode a functional toxin-antitoxin (TA) system belonging to the HicAB family [29]. …”

Section: Resultsmentioning

confidence: 99%

“…The int3 deletion mutant was constructed via homologous recombination as described previously [29, 30]. Briefly, the left flanking region (LA) and right flanking region (RA) of the int3 gene were amplified from the PA1 genome using primer pairs int3-LAF/int3-LAR and int3-RAF/int3-RAR, respectively.…”

Section: Methodsmentioning

confidence: 99%

Characterization and interstrain transfer of prophage pp3 of Pseudomonas aeruginosa

Shen

et al. 2017

PLoS ONE

Self Cite

View full text Add to dashboard Cite

Prophages are major contributors to horizontal gene transfer and drive the evolution and diversification of bacteria. Here, we describe the characterization of a prophage element designated pp3 in the clinical Pseudomonas aeruginosa isolate PA1. pp3 spontaneously excises from the PA1 genome and circularizes at a very high frequency of 25%. pp3 is likely to be a defective prophage due to its inability to form plaques on P. aeruginosa indicator strains, and no phage particles could be detected in PA1 supernatants. The pp3-encoded integrase is essential for excision by mediating site-specific recombination at the 26-bp attachment sequence. Using a filter mating experiment, we demonstrated that pp3 can transfer into P. aeruginosa recipient strains that do not possess this element naturally. Upon transfer, pp3 integrates into the same attachment site as in PA1 and maintains the ability to excise and circularize. Furthermore, pp3 significantly promotes biofilm formation in the recipient. Sequence alignment reveals that the 26-bp attachment site recognized by pp3 is conserved in all P. aeruginosa strains sequenced to date, making it possible that pp3 could be extensively disseminated in P. aeruginosa. This work improves our understanding of the ways in which prophages influence bacterial behavior and evolution.

show abstract

“…Non-growing bacteria are known to be protected from environmental insults 51-53 even if they do not actively combat with stress, as appears to be the case, for example, with most antibiotic-tolerant persister cells 54 . However, despite the potential of TA-encoded toxins to protect bacteria, the deletion of whole TA loci does not usually affect the bacterial fitness 20,27-30,55 , leaving the question of TA systems’ importance in stress tolerance still open.…”

Section: Discussionmentioning

confidence: 99%

Pseudomonas putidachromosomal toxin-antitoxin systems carry neither clear fitness benefits nor big costs

Rosendahl

Tamman

Brauer

et al. 2020

Preprint

View full text Add to dashboard Cite

14Chromosomal toxin-antitoxin (TA) systems are widespread genetic elements among bacteria, yet, 15 despite extensive studies in the last decade, their biological importance remains ambivalent. The ability 16 of TA-encoded toxins to affect stress tolerance supports the hypothesis of TA systems being associated 17 with stress adaptation. However, the deletion of TA genes has usually no fitness consequences, 18 supporting the selfish elements hypothesis. Here, we aimed to evaluate the cost and benefits of 19 chromosomal TA systems to Pseudomonas putida. We show that multiple TA systems do not confer 20 fitness benefits to this bacterium as deletion of 13 TA loci does not influence stress tolerance, 21 persistence and biofilm formation. Our results instead show that TA loci are costly and decrease the 22 competitive fitness of P. putida. Still, the cost of multiple TA systems is low and detectable in certain 23 conditions only. Construction of antitoxin deletion strains showed that only five TA systems code for 24 toxic proteins, while other TA loci have evolved towards reduced toxicity and encode non-toxic or 25 moderately potent proteins. Analysis of P. putida TA systems' homologs among fully sequenced 26 Pseudomonads suggests that the TA loci have been subjected to purifying selection and that TA systems 27 spread among bacteria by horizontal gene transfer.28

show abstract

Identification and Characterization of the HicAB Toxin-Antitoxin System in the Opportunistic Pathogen Pseudomonas aeruginosa

Cited by 43 publications

References 49 publications

The toxin from a ParDE toxin‐antitoxin system found inPseudomonas aeruginosaoffers protection to cells challenged with anti‐gyrase antibiotics

The toxin from a ParDE toxin‐antitoxin system found inPseudomonas aeruginosaoffers protection to cells challenged with anti‐gyrase antibiotics

Characterization and interstrain transfer of prophage pp3 of Pseudomonas aeruginosa

Pseudomonas putidachromosomal toxin-antitoxin systems carry neither clear fitness benefits nor big costs

Contact Info

Product

Resources

About