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bacteria:t3e:avrbs3 [2020/08/07 14:45] jensboch |
bacteria:t3e:avrbs3 [2020/11/30 13:32] st |
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Author: [[https:// | Author: [[https:// | ||
- | Internal reviewer: Jens Boch\\ | + | Internal reviewer: |
- | Expert reviewer: | + | Expert reviewer: |
Class: AvrBs3\\ | Class: AvrBs3\\ | ||
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=== (Experimental) evidence for being a T3E === | === (Experimental) evidence for being a T3E === | ||
- | AvrBs3 is secreted and translocated into the plant via the Hrp type III secretion system (Bonas //et al//., 1991; Van den Ackerveken //et al//., 1996; Bonas //et al//., 1999). In contrast to wild-type bacteria, an //Xcv// mutant carrying a deletion in the conserved //hrp// gene //hrcV// did not secrete AvrBs3 indicating that AvrBs3 is transported by the Hrp system (Rossier //et al//., 1999). In its C-terminal domain, AvrBs3 carries an acidic activation domain which is functional in plant cells (Van den Ackerveken //et al//., 1996). Two nuclear localization signals in the C-terminal domain of AvrBs3 facilitate transport into the plant cell nucleus (Van den Ackerveken //et al//., 1996; Szurek //et al//., 2002). These eukaryotic features support the role of AvrBs3 and members of the TALE family within the eukaryotic host cell. | + | AvrBs3 is secreted and translocated into the plant via the Hrp type III secretion system (Bonas //et al//., 1991; Van den Ackerveken //et al//., 1996; Bonas //et al//., 1999). In contrast to wild-type bacteria, an //Xcv// mutant carrying a deletion in the conserved //hrp// gene //hrcV// did not secrete AvrBs3 indicating that AvrBs3 is transported by the Hrp system (Rossier //et al//., 1999). The first 10 and 50 amino acids of AvrBs3 are required for secretion and translocation, |
=== Regulation === | === Regulation === | ||
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=== Phenotypes === | === Phenotypes === | ||
- | AvrBs3, as well as other members of the TALE-family, function as specific transcription factors in plant cells. These proteins bind to specific sequences in promoters and induce expression of target | + | AvrBs3, as well as other members of the TALE family, function as specific transcription factors in plant cells. These proteins bind to specific sequences in promoters and induce expression of downstream |
- | Expression analysis using gene promoter fusion and western blot analysis demonstrated that //avrBs3// was expressed and resulted in a 122 kDa protein (1164 aa) which was detectable using a specific polyclonal antibody (Bonas //et al//., 1989). The AvrBs3 effector protein elicits two different types of responses in resistant or susceptible plants. Differential cDNA analysis from susceptible pepper plants infected with //Xcv// with or without AvrBs3 led to the discovery of //upa// (upregulated by AvrBs3) genes whose expression is induced by AvrBs3. These //upa// genes all share a conserved promoter element, known as the //UPA// box (Kay //et al.//, 2007). //upa20// act as a master regulator of cell enlargement causing the hypertrophy symptoms associated with AvrBs3. Silencing of //upa20// decreased cell hypertrophy in infected plants while the expression of //upa20// led to hypertrophy in uninfected plants (Kay //et al//., 2007). In resistant pepper plants, the promoter of //Bs3// contains a //UPA// box that is bound by AvrBs3 resulting in the transcription of the gene //Bs3//. //Bs3// encodes a protein that is homologous to flavine-dependent mono-oxygenases and its expression causes rapid cell death. | + | Expression analysis using gene promoter fusion and western blot analysis demonstrated that //avrBs3// was expressed and resulted in a 122 kDa protein (1164 aa) which was detectable using a specific polyclonal antibody (Bonas //et al//., 1989). The AvrBs3 effector protein elicits two different types of responses in resistant or susceptible plants. In susceptible pepper plants (Early Cal Wonder; ECW), hypertrophy (i.e. enlargement of mesophyll cells) is triggered by AvrBs3 (Bonas //et al//., 1989; Bonas //et al//., 1991; Marois //et al//., 2002). // |
- | The central region of the //avrBs3// gene consists | + | In resistant pepper plants, |
- | Gene //Bs3// was introduced into the ECW background to generate near-isogenic line resistant ECW-30R (Bonas | + | The central region of the //avrBs3// gene consists of 17.5 nearly identical 102 bp repeats. Each repeat encodes 34 amino acids (Bonas //et al//., 1989). |
=== Localization === | === Localization === | ||
The //avrBs3// gene is localized on pXV11, a self-transmissible plasmid, and was initially isolated from //Xcv// strain 71-21 (Bonas //et al//., 1989). Using complementation of //Xcv// strain 85-10 (virulent on pepper ECW-30R), a 5-kb fragment including //avrBs3// was discovered (Bonas //et al//., 1989). | The //avrBs3// gene is localized on pXV11, a self-transmissible plasmid, and was initially isolated from //Xcv// strain 71-21 (Bonas //et al//., 1989). Using complementation of //Xcv// strain 85-10 (virulent on pepper ECW-30R), a 5-kb fragment including //avrBs3// was discovered (Bonas //et al//., 1989). | ||
- | === Enzymatic | + | === Molecular |
DNA-binding protein. Transcriptional activator. | DNA-binding protein. Transcriptional activator. | ||
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=== Interaction partners === | === Interaction partners === | ||
- | Importin alpha (Szurek //et al.//, 2001) interacts with the nuclear localization sequences of AvrBs3. The basal transcription factor IIA, gamma subunit from rice interacts with a region in the C-terminal domain of TALEs (Yuan //et al//., 2016) and similar interactions might be possible for AvrBs3, too. AvrBs3 and the TALE-family of effectors bind to DNA (Kay //et al//., 2007; Römer //et al//., 2007) with their N-terminal domain exhibiting general DNA-binding properties (Gao //et al.//, 2012) and the repeat region facilitating specific interaction to DNA bases (Boch //et al//., 2009; Moscou | + | Importin alpha (Szurek //et al.//, 2001) interacts with the nuclear localization sequences of AvrBs3. The basal transcription factor IIA, gamma subunit from rice interacts with a region in the C-terminal domain of TALEs (Yuan //et al//., 2016) and similar interactions might be possible for AvrBs3, too. AvrBs3 and the TALE-family of effectors bind to DNA (Kay //et al//., 2007; Römer //et al//., 2007) with their N-terminal domain exhibiting general DNA-binding properties (Gao //et al.//, 2012) and the repeat region facilitating specific interaction to DNA bases (Boch //et al//., 2009; Moscou |
===== Conservation ===== | ===== Conservation ===== | ||
=== In xanthomonads === | === In xanthomonads === | ||
- | Yes in many pathovars, but not necesssarily all strains within a pathovar. | + | Yes, in many pathovars, but not necesssarily all strains within a pathovar. |
=== In other plant pathogens/ | === In other plant pathogens/ | ||
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Hopkins CM, White FF, Choi SH, Guo A, Leach JE (1992). Identification of a family of avirulence genes from // | Hopkins CM, White FF, Choi SH, Guo A, Leach JE (1992). Identification of a family of avirulence genes from // | ||
- | |||
- | Ji ZY, Xiong L, Zou LF, Li YR, Ma WX, Liu L, Zakria M, Ji GH, Chen GY (2014). AvrXa7-Xa7 mediated defense in rice can be suppressed by transcriptional activator-like effectors TAL6 and TAL11a from // | ||
Kay S, Hahn S, Marois E, Hause G, Bonas U (2007). A bacterial effector acts as a plant transcription factor and induces a cell size regulator. Science 318: 648-651. DOI: [[http:// | Kay S, Hahn S, Marois E, Hause G, Bonas U (2007). A bacterial effector acts as a plant transcription factor and induces a cell size regulator. Science 318: 648-651. DOI: [[http:// | ||
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Rossier O, Wengelnik K, Hahn K, Bonas U (1999). The // | Rossier O, Wengelnik K, Hahn K, Bonas U (1999). The // | ||
- | Scheibner F, Marillonnet S, Büttner D (2017). The TAL effector AvrBs3 from // | + | Scheibner F, Marillonnet S, Büttner D (2017). The TAL effector AvrBs3 from // |
Stella S, Molina R, Yefimenko I, Prieto J, Silva G, Bertonati C, Juillerat A, Duchateau P, Montoya G (2013). Structure of the AvrBs3–DNA complex provides new insights into the initial thymine-recognition mechanism. Acta Cryst. 69: 1707-1716. DOI: [[http:// | Stella S, Molina R, Yefimenko I, Prieto J, Silva G, Bertonati C, Juillerat A, Duchateau P, Montoya G (2013). Structure of the AvrBs3–DNA complex provides new insights into the initial thymine-recognition mechanism. Acta Cryst. 69: 1707-1716. DOI: [[http:// | ||
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Hutin M, Pérez-Quintero AL, Lopez C, Szurek B (2015). MorTAL Kombat: the story of defense against TAL effectors through loss-of-susceptibility. Front. Plant Sci. 6: 535. DOI: [[https:// | Hutin M, Pérez-Quintero AL, Lopez C, Szurek B (2015). MorTAL Kombat: the story of defense against TAL effectors through loss-of-susceptibility. Front. Plant Sci. 6: 535. DOI: [[https:// | ||
- | Scholze H, Boch J (2010). TAL effector-DNA specificity. Virulence 1: 428-432. DOI: [[https://doi.org/10.4161/viru.1.5.12863|10.4161/ | + | Xue J, Lu Z, Liu W, Wang S, Lu D, Wang X, He X (2020). The genetic arms race between plant and //Xanthomonas//: lessons learned from TALE biology. Sci. China Life Sci. 63. DOI: [[https:// |
- | + | ||
- | Scholze H, Boch J (2011). TAL effectors are remote controls for gene activation. Curr. Opin. Microbiol. 14: 47-53. DOI: [[https:// | + | |
- | + | ||
- | Yuan M, Ke Y, Huang R, Ma L, Yang Z, Chu Z, Xiao J, Li X, Wang S (2016). A host basal transcription factor is a key component for infection of rice by TALE-carrying bacteria. Elife 5: DOI: [[https:// | + | |
Zhang J, Yin Z, White F (2015). TAL effectors and the executor //R// genes. Front. Plant Sci. 6: 641. DOI: [[https:// | Zhang J, Yin Z, White F (2015). TAL effectors and the executor //R// genes. Front. Plant Sci. 6: 641. DOI: [[https:// | ||