Plant defensin antibacterial mode of action against Pseudomonas species

10.21203/rs.2.20753/v3 ◽

2020 ◽

Author(s):

Andrew E. Sathoff ◽

Shawn Lewenza ◽

Deborah A. Samac

Keyword(s):

Gene Expression ◽

Antibacterial Activity ◽

Outer Membrane ◽

Pseudomonas Syringae ◽

Mode Of Action ◽

Fluorescent Microscopy ◽

Insertion Site ◽

Membrane Damage ◽

Plant Defensin ◽

Plant Defensins

Abstract Background Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn 5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments. Results Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa . A defensin from Medicago truncatula , MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula , MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. Conclusions MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.

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Plant defensin antibacterial mode of action against Pseudomonas species

10.21203/rs.2.20753/v4 ◽

2020 ◽

Author(s):

Andrew E. Sathoff ◽

Shawn Lewenza ◽

Deborah A. Samac

Keyword(s):

Gene Expression ◽

Antibacterial Activity ◽

Outer Membrane ◽

Pseudomonas Syringae ◽

Mode Of Action ◽

Fluorescent Microscopy ◽

Insertion Site ◽

Membrane Damage ◽

Plant Defensin ◽

Plant Defensins

Abstract Background: Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn 5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments. Results: Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa . A defensin from Medicago truncatula , MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula , MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. Conclusions: MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.

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Plant defensin antibacterial mode of action against Pseudomonas species

10.21203/rs.2.20753/v2 ◽

2020 ◽

Author(s):

Andrew E. Sathoff ◽

Shawn Lewenza ◽

Deborah A. Samac

Keyword(s):

Gene Expression ◽

Antibacterial Activity ◽

Outer Membrane ◽

Pseudomonas Syringae ◽

Mode Of Action ◽

Fluorescent Microscopy ◽

Insertion Site ◽

Membrane Damage ◽

Plant Defensin ◽

Plant Defensins

Abstract Background Though many plant defensins exhibit antibacterial activity, little is known about their antibacterial mode of action (MOA). Antimicrobial peptides with a characterized MOA induce the expression of multiple bacterial outer membrane modifications, which are required for resistance to these membrane-targeting peptides. Mini-Tn 5-lux mutant strains of Pseudomonas aeruginosa with Tn insertions disrupting outer membrane protective modifications were assessed for sensitivity against plant defensin peptides. These transcriptional lux reporter strains were also evaluated for lux gene expression in response to sublethal plant defensin exposure. Also, a plant pathogen, Pseudomonas syringae pv. syringae was modified through transposon mutagenesis to create mutants that are resistant to in vitro MtDef4 treatments. Results Plant defensins displayed specific and potent antibacterial activity against strains of P. aeruginosa . A defensin from Medicago truncatula , MtDef4, induced dose-dependent gene expression of the aminoarabinose modification of LPS and surface polycation spermidine production operons. The ability for MtDef4 to damage bacterial outer membranes was also verified visually through fluorescent microscopy. Another defensin from M. truncatula , MtDef5, failed to induce lux gene expression and limited outer membrane damage was detected with fluorescent microscopy. The transposon insertion site on MtDef4 resistant P. syringae pv. syringae mutants was sequenced, and modifications of ribosomal genes were identified to contribute to enhanced resistance to plant defensin treatments. Conclusions MtDef4 damages the outer membrane similar to polymyxin B, which stimulates antimicrobial peptide resistance mechanisms to plant defensins. MtDef5, appears to have a different antibacterial MOA. Additionally, the MtDef4 antibacterial mode of action may also involve inhibition of translation.

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Plant Defensin Peptides have Antifungal and Antibacterial Activity Against Human and Plant Pathogens

Phytopathology ◽

10.1094/phyto-09-18-0331-r ◽

2019 ◽

Vol 109 (3) ◽

pp. 402-408 ◽

Cited By ~ 12

Author(s):

Andrew E. Sathoff ◽

Siva Velivelli ◽

Dilip M. Shah ◽

Deborah A. Samac

Keyword(s):

Antibacterial Activity ◽

Plant Pathogens ◽

Crown Rot ◽

Plant Defensin ◽

Core Motif ◽

Potential Control ◽

Fungal Plant Pathogens ◽

Plant Defensins ◽

Animal Pathogens

Plant defensins are small, cysteine-rich antimicrobial peptides. These peptides have previously been shown to primarily inhibit the growth of fungal plant pathogens. Plant defensins have a γ-core motif, defined as GXCX3-9C, which is required for their antifungal activity. To evaluate plant defensins as a potential control for a problematic agricultural disease (alfalfa crown rot), short, chemically synthesized peptides containing γ-core motif sequences were screened for activity against numerous crown rot pathogens. These peptides showed both antifungal and, surprisingly, antibacterial activity. Core motif peptides from Medicago truncatula defensins (MtDef4 and MtDef5) displayed high activity against both plant and human bacterial pathogens in vitro. Full-length defensins had higher antimicrobial activity compared with the peptides containing their predictive γ-core motifs. These results show the future promise for controlling a wide array of economically important fungal and bacterial plant pathogens through the transgenic expression of a plant defensin. They also suggest that plant defensins may be an untapped reservoir for development of therapeutic compounds for combating human and animal pathogens.

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Antibacterial activity of new peptides from barbel protein hydrolysates and mode of action via a membrane damage mechanism against Listeria monocytogenes

Journal of Functional Foods ◽

10.1016/j.jff.2014.10.006 ◽

2014 ◽

Vol 11 ◽

pp. 322-329 ◽

Cited By ~ 21

Author(s):

Assaâd Sila ◽

Karima Hedhili ◽

Rémi Przybylski ◽

Semia Ellouz-Chaabouni ◽

Pascal Dhulster ◽

...

Keyword(s):

Antibacterial Activity ◽

Listeria Monocytogenes ◽

Mode Of Action ◽

Membrane Damage ◽

Damage Mechanism ◽

Protein Hydrolysates

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Synthesis and antibacterial activity of new peptides from Alfalfa RuBisCO protein hydrolysates and mode of action via a membrane damage mechanism against Listeria innocua

Microbial Pathogenesis ◽

10.1016/j.micpath.2017.12.009 ◽

2018 ◽

Vol 115 ◽

pp. 41-49 ◽

Cited By ~ 4

Author(s):

Sabrine Kobbi ◽

Naima Nedjar ◽

Nourdine Chihib ◽

Rafik Balti ◽

Mickael Chevalier ◽

...

Keyword(s):

Antibacterial Activity ◽

Mode Of Action ◽

Membrane Damage ◽

Damage Mechanism ◽

Protein Hydrolysates ◽

Listeria Innocua

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Antibacterial activities, proposed mode of action and cytotoxicity of leaf extracts from Triumfetta welwitschii against Pseudomonas aeruginosa

BMC Complementary and Alternative Medicine ◽

10.1186/s12906-019-2713-3 ◽

2019 ◽

Vol 19 (1) ◽

Author(s):

Molly Mombeshora ◽

Stanley Mukanganyama

Keyword(s):

Pseudomonas Aeruginosa ◽

Antibacterial Activity ◽

Nosocomial Infections ◽

Mode Of Action ◽

Antimicrobial Agents ◽

Membrane Damage ◽

Membrane Integrity ◽

Antibacterial Activities ◽

Leaf Extracts ◽

Broth Microdilution Method

Abstract Background Pseudomonas aeruginosa has become a main cause of Gram-negative infection, particularly in patients with compromised immunity. High rates of resistance to antibiotics are associated with nosocomial infections caused by P. aeruginosa strains. The search for novel antimicrobials has been necessitated by the emergence of antimicrobial resistance in some bacteria Plant-based antimicrobials has great potential to combat microbial infections using a variety of mechanisms. Triumfetta welwitschii plant roots are traditionally used to treat symptoms of diarrhoea and fever, suggesting that it possess antimicrobial and immunomodulatory effects. Since research investigating antimicrobial properties of the roots of Triumfetta welwitschii has been explored, there is need to investigate the antimicrobial activity of its leaf extracts in order to probe their prospective use as new antimicrobial agents that can be used to combat nosocomial infections. The objective of this study was to evaluate the antibacterial activities, the mode of action and cytotoxicity of T. welwitschii leaf extracts. Method Extracts of T. welwitschii leaves were obtained using eight different solvents, the serial exhaustive extraction method and the cold maceration technique. In vitro antibacterial activity evaluation of the extracts was done on eight bacterial isolates using the broth microdilution method. The mode of action for the most potent extracts was investigated using the rhodamine 6G efflux assay and the propidium iodide-based membrane damage assay. Toxicity of the extracts was evaluated using the haemolytic and MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assays. Results The results showed that acetone, ethanol and dichlorometane: methanol extracts had the most potent antibacterial activities against Pseudomonas aeruginosa (ATCC 27853). All three extracts caused membrane disruption of P. aeruginosa as shown by nucleic acid leakage. All three extracts were unable to inhibit efflux pumps. Conclusion The presence of antibacterial activities and low toxicity shown by the extracts indicates that the plant may be a source of effective antibacterial against some bacterial infections caused by P. aeruginosa. The disruption of membrane integrity is one possible mode of action of antibacterial activity of the potent extracts.

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