Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin
Abstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action i...
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| Format: | Article |
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BMC
2021-04-01
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| Series: | BMC Microbiology |
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| Online Access: | https://doi.org/10.1186/s12866-021-02176-4 |
| _version_ | 1818339085717078016 |
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| author | Tessa B. Moyer Ashleigh L. Purvis Andrew J. Wommack Leslie M. Hicks |
| author_facet | Tessa B. Moyer Ashleigh L. Purvis Andrew J. Wommack Leslie M. Hicks |
| author_sort | Tessa B. Moyer |
| collection | DOAJ |
| description | Abstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action including membrane lysis and ribosomal inhibition. Herein, a truncated synthetic analog containing the γ-core motif of Amaranthus tricolor DEF2 (Atr-DEF2) reveals Gram-negative antibacterial activity and its mechanism of action is probed via proteomics, outer membrane permeability studies, and iron reduction/chelation assays. Results Atr-DEF2(G39-C54) demonstrated activity against two Gram-negative human bacterial pathogens, Escherichia coli and Klebsiella pneumoniae. Quantitative proteomics revealed changes in the E. coli proteome in response to treatment of sub-lethal concentrations of the truncated defensin, including bacterial outer membrane (OM) and iron acquisition/processing related proteins. Modification of OM charge is a common response of Gram-negative bacteria to membrane lytic antimicrobial peptides (AMPs) to reduce electrostatic interactions, and this mechanism of action was confirmed for Atr-DEF2(G39-C54) via an N-phenylnaphthalen-1-amine uptake assay. Additionally, in vitro assays confirmed the capacity of Atr-DEF2(G39-C54) to reduce Fe3+ and chelate Fe2+ at cell culture relevant concentrations, thus limiting the availability of essential enzymatic cofactors. Conclusions This study highlights the utility of plant defensin γ-core motif synthetic analogs for characterization of novel defensin activity. Proteomic changes in E. coli after treatment with Atr-DEF2(G39-C54) supported the hypothesis that membrane lysis is an important component of γ-core motif mediated antibacterial activity but also emphasized that other properties, such as metal sequestration, may contribute to a multifaceted mechanism of action. |
| first_indexed | 2024-12-13T15:21:24Z |
| format | Article |
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| issn | 1471-2180 |
| language | English |
| last_indexed | 2024-12-13T15:21:24Z |
| publishDate | 2021-04-01 |
| publisher | BMC |
| record_format | Article |
| series | BMC Microbiology |
| spelling | doaj.art-4632d7ffa95d408f99b038c5906ed5da2022-12-21T23:40:34ZengBMCBMC Microbiology1471-21802021-04-0121111210.1186/s12866-021-02176-4Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensinTessa B. Moyer0Ashleigh L. Purvis1Andrew J. Wommack2Leslie M. Hicks3Department of Chemistry, University of North Carolina at Chapel HillDepartment of Chemistry, High Point UniversityDepartment of Chemistry, High Point UniversityDepartment of Chemistry, University of North Carolina at Chapel HillAbstract Background Plant defensins are a broadly distributed family of antimicrobial peptides which have been primarily studied for agriculturally relevant antifungal activity. Recent studies have probed defensins against Gram-negative bacteria revealing evidence for multiple mechanisms of action including membrane lysis and ribosomal inhibition. Herein, a truncated synthetic analog containing the γ-core motif of Amaranthus tricolor DEF2 (Atr-DEF2) reveals Gram-negative antibacterial activity and its mechanism of action is probed via proteomics, outer membrane permeability studies, and iron reduction/chelation assays. Results Atr-DEF2(G39-C54) demonstrated activity against two Gram-negative human bacterial pathogens, Escherichia coli and Klebsiella pneumoniae. Quantitative proteomics revealed changes in the E. coli proteome in response to treatment of sub-lethal concentrations of the truncated defensin, including bacterial outer membrane (OM) and iron acquisition/processing related proteins. Modification of OM charge is a common response of Gram-negative bacteria to membrane lytic antimicrobial peptides (AMPs) to reduce electrostatic interactions, and this mechanism of action was confirmed for Atr-DEF2(G39-C54) via an N-phenylnaphthalen-1-amine uptake assay. Additionally, in vitro assays confirmed the capacity of Atr-DEF2(G39-C54) to reduce Fe3+ and chelate Fe2+ at cell culture relevant concentrations, thus limiting the availability of essential enzymatic cofactors. Conclusions This study highlights the utility of plant defensin γ-core motif synthetic analogs for characterization of novel defensin activity. Proteomic changes in E. coli after treatment with Atr-DEF2(G39-C54) supported the hypothesis that membrane lysis is an important component of γ-core motif mediated antibacterial activity but also emphasized that other properties, such as metal sequestration, may contribute to a multifaceted mechanism of action.https://doi.org/10.1186/s12866-021-02176-4DefensinsAmaranthus tricolorMembrane lysisIron chelationIron reductionEscherichia coli |
| spellingShingle | Tessa B. Moyer Ashleigh L. Purvis Andrew J. Wommack Leslie M. Hicks Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin BMC Microbiology Defensins Amaranthus tricolor Membrane lysis Iron chelation Iron reduction Escherichia coli |
| title | Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin |
| title_full | Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin |
| title_fullStr | Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin |
| title_full_unstemmed | Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin |
| title_short | Proteomic response of Escherichia coli to a membrane lytic and iron chelating truncated Amaranthus tricolor defensin |
| title_sort | proteomic response of escherichia coli to a membrane lytic and iron chelating truncated amaranthus tricolor defensin |
| topic | Defensins Amaranthus tricolor Membrane lysis Iron chelation Iron reduction Escherichia coli |
| url | https://doi.org/10.1186/s12866-021-02176-4 |
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