scholarly journals Inactivation of the gene encoding the cationic antimicrobial peptide resistance factor MprF increases biofilm formation but reduces invasiveness of Listeria monocytogenes

2020 ◽  
Author(s):  
J. Nowak ◽  
S.B. Visnovsky ◽  
C.D. Cruz ◽  
G.C. Fletcher ◽  
A.H.M. Vliet ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Antimicrobial Peptide ◽  
Biofilm Formation ◽  
Resistance Factor ◽  
Gene Encoding ◽  
Cationic Antimicrobial Peptide ◽  
Antimicrobial Peptide Resistance

scholarly journals Subinhibitory concentrations of the cationic antimicrobial peptide colistin induce the pseudomonas quinolone signal in Pseudomonas aeruginosa

Microbiology ◽  
2009 ◽  
Vol 155 (9) ◽  
pp. 2826-2837 ◽  
Author(s):  
Joanne Cummins ◽  
F. Jerry Reen ◽  
Christine Baysse ◽  
Marlies J. Mooij ◽  
Fergal O'Gara
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Peptide ◽  
Biofilm Formation ◽  
Bacterial Colonization ◽  
Central Component ◽  
Functional Genomic ◽  
Cationic Antimicrobial Peptide ◽  
Altered Expression ◽  
Pseudomonas Quinolone Signal ◽  
Subinhibitory Concentrations

Colistin is an important cationic antimicrobial peptide (CAMP) in the fight against Pseudomonas aeruginosa infection in cystic fibrosis (CF) lungs. The effects of subinhibitory concentrations of colistin on gene expression in P. aeruginosa were investigated by transcriptome and functional genomic approaches. Analysis revealed altered expression of 30 genes representing a variety of pathways associated with virulence and bacterial colonization in chronic infection. These included response to osmotic stress, motility, and biofilm formation, as well as genes associated with LPS modification and quorum sensing (QS). Most striking was the upregulation of Pseudomonas quinolone signal (PQS) biosynthesis genes, including pqsH, pqsB and pqsE, and the phenazine biosynthesis operon. Induction of this central component of the QS network following exposure to subinhibitory concentrations of colistin may represent a switch to a more robust population, with increased fitness in the competitive environment of the CF lung.

scholarly journals Identification of a Genetic Locus Responsible for Antimicrobial Peptide Resistance inClostridium difficile

2010 ◽  
Vol 79 (1) ◽  
pp. 167-176 ◽  
Author(s):  
Shonna M. McBride ◽  
Abraham L. Sonenshein
Keyword(s):  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Abc Transporter ◽  
Genetic Locus ◽  
Polymyxin B ◽  
Transcriptional Analysis ◽  
Cationic Antimicrobial Peptide ◽  
Low Levels ◽  
Antimicrobial Peptide Resistance ◽  
Abc Transporter Genes

ABSTRACTClostridium difficilecauses chronic intestinal disease, yet little is understood about how the bacterium interacts with and survives in the host. To colonize the intestine and cause persistent disease, the bacterium must circumvent killing by host innate immune factors, such as cationic antimicrobial peptides (CAMPs). In this study, we investigated the effect of model CAMPs on growth and found thatC. difficileis not only sensitive to these compounds but also responds to low levels of CAMPs by expressing genes that lead to CAMP resistance. By plating the bacterium on medium containing the CAMP nisin, we isolated a mutant capable of growing in three times the inhibitory concentration of CAMPs. This mutant also showed increased resistance to the CAMPs gallidermin and polymyxin B, demonstrating tolerance to different types of antimicrobial peptides. We identified the mutated gene responsible for the resistance phenotype as CD1352. This gene encodes a putative orphan histidine kinase that lies adjacent to a predicted ABC transporter operon (CD1349 to CD1351). Transcriptional analysis of the ABC transporter genes revealed that this operon was upregulated in the presence of nisin in wild-type cells and was more highly expressed in the CD1352 mutant. The insertional disruption of the CD1349 gene resulted in significant decreases in resistance to the CAMPs nisin and gallidermin but not polymyxin B. Because of their role in cationic antimicrobial peptide resistance, we propose the designationcprABCfor genes CD1349 to CD1351 andcprKfor the CD1352 gene. These results provide the first evidence of aC. difficilegene associated with antimicrobial peptide resistance.

scholarly journals A Putative ABC Transporter Is Involved in Negative Regulation of Biofilm Formation by Listeria monocytogenes

2008 ◽  
Vol 74 (24) ◽  
pp. 7675-7683 ◽  
Author(s):  
Xinna Zhu ◽  
Fei Long ◽  
Yonghui Chen ◽  
Susanne Knøchel ◽  
Qunxin She ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Abc Transporter ◽  
Biofilm Formation ◽  
Negative Regulation ◽  
Atp Binding ◽  
Coding Region ◽  
Gene Encoding ◽  
Food Borne ◽  
Atp Binding Protein

ABSTRACT Listeria monocytogenes may persist for long periods in food processing environments. In some instances, this may be due to aggregation or biofilm formation. To investigate the mechanism controlling biofilm formation in the food-borne pathogen L. monocytogenes, we characterized LM-49, a mutant with enhanced ability of biofilm formation generated via transposon Tn917 mutagenesis of L. monocytogenes 4b G. In this mutant, a Tn917 insertion has disrupted the coding region of the gene encoding a putative ATP-binding cassette (ABC) transporter permease identical to Lmof2365_1771 (a putative ABC transporter permease) presented in the sequenced strain L. monocytogenes strain 4b F2365. This disrupted gene, denoted lm.G_1771, encoded a protein with 10 transmembrane helixes. The revertant, LM-49RE, was obtained by replacing lm.G_1771::Tn917 with lm.G_1771 via homologous recombination. We found that LM-49RE formed the same amount of biofilm biomass as the wild-type strain. Furthermore, transcription of the downstream lm.G_1770 gene was not influenced by the upstream Tn917 insertion, and the presence of Tn917 has no effect on biofilm formation. These results suggest that lm.G_1771 was solely responsible for the negative regulation of biofilm formation by L. monocytogenes 4b G. The immediate gene upstream of lm.G_1771 encoded an ATP-binding protein. Bioinformatics analysis suggested that these two genes were organized into an operon and that their proteins formed an export ABC transporter. Here, we report the characterization of the mutant and identification of a novel ABC transporter that functions in negative regulation of biofilm formation in L. monocytogenes.

scholarly journals Induction by Cationic Antimicrobial Peptides and Involvement in Intrinsic Polymyxin and Antimicrobial Peptide Resistance, Biofilm Formation, and Swarming Motility of PsrA in Pseudomonas aeruginosa

2008 ◽  
Vol 190 (16) ◽  
pp. 5624-5634 ◽  
Author(s):  
W. James Gooderham ◽  
Manjeet Bains ◽  
Joseph B. McPhee ◽  
Irith Wiegand ◽  
Robert E. W. Hancock
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antimicrobial Peptides ◽  
Antimicrobial Peptide ◽  
Outer Membrane ◽  
Biofilm Formation ◽  
Metabolic Energy ◽  
Wild Type ◽  
Swarming Motility ◽  
Cationic Antimicrobial Peptides ◽  
Antimicrobial Peptide Resistance

ABSTRACT Pseudomonas aeruginosa is an important opportunistic pathogen that causes infections that can be extremely difficult to treat due to its high intrinsic antibiotic resistance and broad repertoire of virulence factors, both of which are highly regulated. It is demonstrated here that the psrA gene, encoding a transcriptional regulator, was upregulated in response to subinhibitory concentrations of cationic antimicrobial peptides. Compared to the wild type and the complemented mutant, a P. aeruginosa PAO1 psrA::Tn5 mutant displayed intrinsic supersusceptibility to polymyxin B, a last-resort antimicrobial used against multidrug-resistant infections, and the bovine neutrophil antimicrobial peptide indolicidin; this supersusceptibility phenotype correlated with increased outer membrane permeabilization by these agents. The psrA mutant was also defective in simple biofilm formation, rapid attachment, and swarming motility, all of which could be complemented by the cloned psrA gene. The role of PsrA in global gene regulation was studied by comparing the psrA mutant to the wild type by microarray analysis, demonstrating that 178 genes were up- or downregulated ≥2-fold (P ≤ 0.05). Dysregulated genes included those encoding certain known PsrA targets, those encoding the type III secretion apparatus and effectors, adhesion and motility genes, and a variety of metabolic, energy metabolism, and outer membrane permeability genes. This suggests that PsrA might be a key regulator of antimicrobial peptide resistance and virulence.

scholarly journals Phosphoglucomutase of Yersinia pestis Is Required for Autoaggregation and Polymyxin B Resistance

2009 ◽  
Vol 78 (3) ◽  
pp. 1163-1175 ◽  
Author(s):  
Suleyman Felek ◽  
Artur Muszyński ◽  
Russell W. Carlson ◽  
Tiffany M. Tsang ◽  
B. Joseph Hinnebusch ◽  
...  
Keyword(s):  
Antimicrobial Peptide ◽  
Yersinia Pestis ◽  
Polymyxin B ◽  
Surface Structures ◽  
Tandem Ms ◽  
Gene Encoding ◽  
Targeted Deletion ◽  
Transposon Insertion ◽  
Increased Sensitivity ◽  
Antimicrobial Peptide Resistance

ABSTRACT Yersinia pestis, the causative agent of plague, autoaggregates within a few minutes of cessation of shaking when grown at 28°C. To identify the autoaggregation factor of Y. pestis, we performed mariner-based transposon mutagenesis. Autoaggregation-defective mutants from three different pools were identified, each with a transposon insertion at a different position within the gene encoding phosphoglucomutase (pgmA; y1258). Targeted deletion of pgmA in Y. pestis KIM5 also resulted in loss of autoaggregation. Given the previously defined role for phosphoglucomutase in antimicrobial peptide resistance in other organisms, we tested the KIM5 ΔpgmA mutant for antimicrobial peptide sensitivity. The ΔpgmA mutant displayed >1,000-fold increased sensitivity to polymyxin B compared to the parental Y. pestis strain, KIM5. This sensitivity is not due to changes in lipopolysaccharide (LPS) since the LPSs from both Y. pestis KIM5 and the ΔpgmA mutant are identical based on a comparison of their structures by mass spectrometry (MS), tandem MS, and nuclear magnetic resonance analyses. Furthermore, the ability of polymyxin B to neutralize LPS toxicity was identical for LPS purified from both KIM5 and the ΔpgmA mutant. Our results indicate that increased polymyxin B sensitivity of the ΔpgmA mutant is due to changes in surface structures other than LPS. Experiments with mice via the intravenous and intranasal routes did not demonstrate any virulence defect for the ΔpgmA mutant, nor was flea colonization or blockage affected. Our findings suggest that the activity of PgmA results in modification and/or elaboration of a surface component of Y. pestis responsible for autoaggregation and polymyxin B resistance.

Indole signaling decreases biofilm formation and related virulence of Listeria monocytogenes

2020 ◽  
Vol 367 (14) ◽  
Author(s):  
Paramaporn Rattanaphan ◽  
Pimonsri Mittraparp-Arthorn ◽  
Kanitta Srinoun ◽  
Varaporn Vuddhakul ◽  
Natta Tansila
Keyword(s):  
Listeria Monocytogenes ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Cell Aggregation ◽  
Signal Molecules ◽  
Bacterial Survival ◽  
Gene Encoding ◽  
Cellular Processes ◽  
Molecular Approaches ◽  
Indole Signaling

ABSTRACT Bacterial communication system known as quorum sensing (QS) is a pivotal system for bacterial survival, adaptation and pathogenesis. Members in the multicellular community may synthesize or acquire a signaling molecule in order to elicit downstream cellular processes. Roles of indole and derivatives, a new class of quorum-sensing signal molecules, in various bacterial physiologies and virulence have been reported recently. Indole is normally found in mammal gastrointestinal tract as a metabolite of tryptophan metabolism by microbiota. Therefore, interspecies connection via indole signaling among commensal bacteria and enteric pathogens could be anticipated. Effects of indole exposure on the virulence of Listeria monocytogenes were investigated by phenotypic and molecular approaches. Results demonstrated that synthetic indole and indole-rich conditioned medium significantly diminished biofilm formation and related virulence of L. monocytogenes including motility, cell aggregation and exopolysaccharide production. Transcript levels of virulence-associated (pssE, dltA, flaA, fliI, motB, agrA and hly) and regulatory genes (codY, sigB, prfA and gmaR) were substantially downregulated in indole-treated cells. Only mogR gene encoding for a repressor of motility genes was upregulated after indole exposure. Our findings raise the possibility that L. monocytogenes may acquire indole signaling from gut microbiota for resource-effective adaptation upon transition to new environment.

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