Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism
<i>Penicillium expansum</i> is a necrotrophic wound fungal pathogen that secrets virulence factors to kill host cells including cell wall degrading enzymes (CWDEs), proteases, and mycotoxins such as patulin. During the interaction between <i>P. expansum</i> and its fruit host...
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MDPI AG
2021-10-01
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| Series: | Journal of Fungi |
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| Online Access: | https://www.mdpi.com/2309-608X/7/10/826 |
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| author | Shlomit Dor Dov Prusky Livnat Afriat-Jurnou |
| author_facet | Shlomit Dor Dov Prusky Livnat Afriat-Jurnou |
| author_sort | Shlomit Dor |
| collection | DOAJ |
| description | <i>Penicillium expansum</i> is a necrotrophic wound fungal pathogen that secrets virulence factors to kill host cells including cell wall degrading enzymes (CWDEs), proteases, and mycotoxins such as patulin. During the interaction between <i>P. expansum</i> and its fruit host, these virulence factors are strictly modulated by intrinsic regulators and extrinsic environmental factors. In recent years, there has been a rapid increase in research on the molecular mechanisms of pathogenicity in <i>P. expansum</i>; however, less is known regarding the bacteria–fungal communication in the fruit environment that may affect pathogenicity. Many bacterial species use quorum-sensing (QS), a population density-dependent regulatory mechanism, to modulate the secretion of quorum-sensing signaling molecules (QSMs) as a method to control pathogenicity. N-acyl homoserine lactones (AHLs) are Gram-negative QSMs. Therefore, QS is considered an antivirulence target, and enzymes degrading these QSMs, named quorum-quenching enzymes, have potential antimicrobial properties. Here, we demonstrate that a bacterial AHL lactonase can also efficiently degrade a fungal mycotoxin. The mycotoxin is a lactone, patulin secreted by fungi such as <i>P. expansum</i>. The bacterial lactonase hydrolyzed patulin at high catalytic efficiency, with a <i>k<sub>cat</sub></i> value of 0.724 ± 0.077 s<sup>−1</sup> and K<sub>M</sub> value of 116 ± 33.98 μM. The calculated specific activity (<i>k<sub>cat</sub></i>/K<sub>M</sub>) showed a value of 6.21 × 10<sup>3</sup> s<sup>−1</sup>M<sup>−1</sup>. While the incubation of <i>P. expansum</i> spores with the purified lactonase did not inhibit spore germination, it inhibited colonization by the pathogen in apples. Furthermore, adding the purified enzyme to <i>P. expansum</i> culture before infecting apples resulted in reduced expression of genes involved in patulin biosynthesis and fungal cell wall biosynthesis. Some AHL-secreting bacteria also express AHL lactonase. Here, phylogenetic and structural analysis was used to identify putative lactonase in <i>P. expansum</i>. Furthermore, following recombinant expression and purification of the newly identified fungal enzyme, its activity with patulin was verified. These results indicate a possible role for patulin and lactonases in inter-kingdom communication between fungi and bacteria involved in fungal colonization and antagonism and suggest that QQ lactonases can be used as potential antifungal post-harvest treatment. |
| first_indexed | 2024-03-10T06:27:46Z |
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| publishDate | 2021-10-01 |
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| spelling | doaj.art-43e9afc6e8b14f36aee4013df876b04e2023-11-22T18:47:05ZengMDPI AGJournal of Fungi2309-608X2021-10-0171082610.3390/jof7100826Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial AntagonismShlomit Dor0Dov Prusky1Livnat Afriat-Jurnou2Migal-Galilee Research Institute, Kiryat Shmona 11016, IsraelDepartment of Postharvest Science, Agricultural Research Organization, Rishon LeZion 7505101, IsraelMigal-Galilee Research Institute, Kiryat Shmona 11016, Israel<i>Penicillium expansum</i> is a necrotrophic wound fungal pathogen that secrets virulence factors to kill host cells including cell wall degrading enzymes (CWDEs), proteases, and mycotoxins such as patulin. During the interaction between <i>P. expansum</i> and its fruit host, these virulence factors are strictly modulated by intrinsic regulators and extrinsic environmental factors. In recent years, there has been a rapid increase in research on the molecular mechanisms of pathogenicity in <i>P. expansum</i>; however, less is known regarding the bacteria–fungal communication in the fruit environment that may affect pathogenicity. Many bacterial species use quorum-sensing (QS), a population density-dependent regulatory mechanism, to modulate the secretion of quorum-sensing signaling molecules (QSMs) as a method to control pathogenicity. N-acyl homoserine lactones (AHLs) are Gram-negative QSMs. Therefore, QS is considered an antivirulence target, and enzymes degrading these QSMs, named quorum-quenching enzymes, have potential antimicrobial properties. Here, we demonstrate that a bacterial AHL lactonase can also efficiently degrade a fungal mycotoxin. The mycotoxin is a lactone, patulin secreted by fungi such as <i>P. expansum</i>. The bacterial lactonase hydrolyzed patulin at high catalytic efficiency, with a <i>k<sub>cat</sub></i> value of 0.724 ± 0.077 s<sup>−1</sup> and K<sub>M</sub> value of 116 ± 33.98 μM. The calculated specific activity (<i>k<sub>cat</sub></i>/K<sub>M</sub>) showed a value of 6.21 × 10<sup>3</sup> s<sup>−1</sup>M<sup>−1</sup>. While the incubation of <i>P. expansum</i> spores with the purified lactonase did not inhibit spore germination, it inhibited colonization by the pathogen in apples. Furthermore, adding the purified enzyme to <i>P. expansum</i> culture before infecting apples resulted in reduced expression of genes involved in patulin biosynthesis and fungal cell wall biosynthesis. Some AHL-secreting bacteria also express AHL lactonase. Here, phylogenetic and structural analysis was used to identify putative lactonase in <i>P. expansum</i>. Furthermore, following recombinant expression and purification of the newly identified fungal enzyme, its activity with patulin was verified. These results indicate a possible role for patulin and lactonases in inter-kingdom communication between fungi and bacteria involved in fungal colonization and antagonism and suggest that QQ lactonases can be used as potential antifungal post-harvest treatment.https://www.mdpi.com/2309-608X/7/10/826<i>Penicillium expansum</i>patulinmycotoxinquorum-quenching (QQ) lactonasefungal pathogens |
| spellingShingle | Shlomit Dor Dov Prusky Livnat Afriat-Jurnou Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism Journal of Fungi <i>Penicillium expansum</i> patulin mycotoxin quorum-quenching (QQ) lactonase fungal pathogens |
| title | Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism |
| title_full | Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism |
| title_fullStr | Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism |
| title_full_unstemmed | Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism |
| title_short | Bacterial Quorum-Quenching Lactonase Hydrolyzes Fungal Mycotoxin and Reduces Pathogenicity of <i>Penicillium expansum</i>—Suggesting a Mechanism of Bacterial Antagonism |
| title_sort | bacterial quorum quenching lactonase hydrolyzes fungal mycotoxin and reduces pathogenicity of i penicillium expansum i suggesting a mechanism of bacterial antagonism |
| topic | <i>Penicillium expansum</i> patulin mycotoxin quorum-quenching (QQ) lactonase fungal pathogens |
| url | https://www.mdpi.com/2309-608X/7/10/826 |
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