Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors
The type VI secretion system (T6SS) assembles into a contractile nanomachine to inject effectors across bacterial membranes for secretion. The Agrobacterium tumefaciens species complex is a group of soil inhabitants and phytopathogens that deploys T6SS as an antibacterial weapon against bacterial co...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2024-02-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2024.1351590/full |
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| author | Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Katherine L. Pintor Pei-Yu Hsieh Yee-Wai Cheung Li-Kang Sung Li-Kang Sung Li-Kang Sung Yu-Ling Shih Erh-Min Lai Erh-Min Lai Erh-Min Lai |
| author_facet | Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Katherine L. Pintor Pei-Yu Hsieh Yee-Wai Cheung Li-Kang Sung Li-Kang Sung Li-Kang Sung Yu-Ling Shih Erh-Min Lai Erh-Min Lai Erh-Min Lai |
| author_sort | Mary Nia M. Santos |
| collection | DOAJ |
| description | The type VI secretion system (T6SS) assembles into a contractile nanomachine to inject effectors across bacterial membranes for secretion. The Agrobacterium tumefaciens species complex is a group of soil inhabitants and phytopathogens that deploys T6SS as an antibacterial weapon against bacterial competitors at both inter-species and intra-species levels. The A. tumefaciens strain 1D1609 genome encodes one main T6SS gene cluster and four vrgG genes (i.e., vgrGa-d), each encoding a spike protein as an effector carrier. A previous study reported that vgrGa-associated gene 2, named v2a, encodes a His-Me finger nuclease toxin (also named HNH/ENDO VII nuclease), contributing to DNase-mediated antibacterial activity. However, the functions and roles of other putative effectors remain unknown. In this study, we identified vgrGc-associated gene 2 (v2c) that encodes another His-Me finger nuclease but with a distinct Serine Histidine Histidine (SHH) motif that differs from the AHH motif of V2a. We demonstrated that the ectopic expression of V2c caused growth inhibition, plasmid DNA degradation, and cell elongation in Escherichia coli using DNAse activity assay and fluorescence microscopy. The cognate immunity protein, V3c, neutralizes the DNase activity and rescues the phenotypes of growth inhibition and cell elongation. Ectopic expression of V2c DNase-inactive variants retains the cell elongation phenotype, while V2a induces cell elongation in a DNase-mediated manner. We also showed that the amino acids of conserved SHH and HNH motifs are responsible for the V2c DNase activity in vivo and in vitro. Notably, V2c also mediated the DNA degradation and cell elongation of the target cell in the context of interbacterial competition. Importantly, V2a and V2c exhibit different capacities against different bacterial species and function synergistically to exert stronger antibacterial activity against the soft rot phytopathogen, Dickeya dadantii. |
| first_indexed | 2024-03-07T19:13:26Z |
| format | Article |
| id | doaj.art-995308b5bff74b1595d75fc96b39a916 |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-03-07T19:13:26Z |
| publishDate | 2024-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-995308b5bff74b1595d75fc96b39a9162024-02-29T17:40:16ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2024-02-011510.3389/fmicb.2024.13515901351590Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitorsMary Nia M. Santos0Mary Nia M. Santos1Mary Nia M. Santos2Mary Nia M. Santos3Katherine L. Pintor4Pei-Yu Hsieh5Yee-Wai Cheung6Li-Kang Sung7Li-Kang Sung8Li-Kang Sung9Yu-Ling Shih10Erh-Min Lai11Erh-Min Lai12Erh-Min Lai13Institute of Plant and Microbial Biology, Academia Sinica, Taipei, TaiwanMolecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, TaiwanGraduate Institute of Biotechnology, National Chung-Hsing University, Taichung, TaiwanAquaculture Research and Development Division, Department of Agriculture-National Fisheries Research and Development Institute (DA-NFRDI), Manila, PhilippinesInstitute of Plant and Microbial Biology, Academia Sinica, Taipei, TaiwanInstitute of Biological Chemistry, Academia Sinica, Taipei, TaiwanInstitute of Plant and Microbial Biology, Academia Sinica, Taipei, TaiwanInstitute of Plant and Microbial Biology, Academia Sinica, Taipei, TaiwanMolecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, TaiwanGraduate Institute of Biotechnology, National Chung-Hsing University, Taichung, TaiwanInstitute of Biological Chemistry, Academia Sinica, Taipei, TaiwanInstitute of Plant and Microbial Biology, Academia Sinica, Taipei, TaiwanMolecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University and Academia Sinica, Taipei, TaiwanBiotechnology Center, National Chung-Hsing University, Taichung, TaiwanThe type VI secretion system (T6SS) assembles into a contractile nanomachine to inject effectors across bacterial membranes for secretion. The Agrobacterium tumefaciens species complex is a group of soil inhabitants and phytopathogens that deploys T6SS as an antibacterial weapon against bacterial competitors at both inter-species and intra-species levels. The A. tumefaciens strain 1D1609 genome encodes one main T6SS gene cluster and four vrgG genes (i.e., vgrGa-d), each encoding a spike protein as an effector carrier. A previous study reported that vgrGa-associated gene 2, named v2a, encodes a His-Me finger nuclease toxin (also named HNH/ENDO VII nuclease), contributing to DNase-mediated antibacterial activity. However, the functions and roles of other putative effectors remain unknown. In this study, we identified vgrGc-associated gene 2 (v2c) that encodes another His-Me finger nuclease but with a distinct Serine Histidine Histidine (SHH) motif that differs from the AHH motif of V2a. We demonstrated that the ectopic expression of V2c caused growth inhibition, plasmid DNA degradation, and cell elongation in Escherichia coli using DNAse activity assay and fluorescence microscopy. The cognate immunity protein, V3c, neutralizes the DNase activity and rescues the phenotypes of growth inhibition and cell elongation. Ectopic expression of V2c DNase-inactive variants retains the cell elongation phenotype, while V2a induces cell elongation in a DNase-mediated manner. We also showed that the amino acids of conserved SHH and HNH motifs are responsible for the V2c DNase activity in vivo and in vitro. Notably, V2c also mediated the DNA degradation and cell elongation of the target cell in the context of interbacterial competition. Importantly, V2a and V2c exhibit different capacities against different bacterial species and function synergistically to exert stronger antibacterial activity against the soft rot phytopathogen, Dickeya dadantii.https://www.frontiersin.org/articles/10.3389/fmicb.2024.1351590/fulltype VI secretion system (T6SS)interbacterial antagonismbacterial toxinnucleaseAgrobacterium |
| spellingShingle | Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Mary Nia M. Santos Katherine L. Pintor Pei-Yu Hsieh Yee-Wai Cheung Li-Kang Sung Li-Kang Sung Li-Kang Sung Yu-Ling Shih Erh-Min Lai Erh-Min Lai Erh-Min Lai Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors Frontiers in Microbiology type VI secretion system (T6SS) interbacterial antagonism bacterial toxin nuclease Agrobacterium |
| title | Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| title_full | Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| title_fullStr | Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| title_full_unstemmed | Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| title_short | Agrobacteria deploy two classes of His-Me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| title_sort | agrobacteria deploy two classes of his me finger superfamily nuclease effectors exerting different antibacterial capacities against specific bacterial competitors |
| topic | type VI secretion system (T6SS) interbacterial antagonism bacterial toxin nuclease Agrobacterium |
| url | https://www.frontiersin.org/articles/10.3389/fmicb.2024.1351590/full |
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