title: Breaking the DNA-binding code of Ralstonia solanacearum TAL effectors provides new possibilities to generate plant resistance genes against bacterial wilt disease.
abstract: Ralstonia solanacearum is a devastating bacterial phytopathogen with a broad host range. Ralstonia solanacearum injected effector proteins (Rips) are key to the successful invasion of host plants. We have characterized Brg11(hrpB-regulated 11), the first identified member of a class of Rips with high sequence similarity to the transcription activator-like (TAL) effectors of Xanthomonas spp., collectively termed RipTALs. Fluorescence microscopy of in planta expressed RipTALs showed nuclear localization. Domain swaps between Brg11 and Xanthomonas TAL effector (TALE) AvrBs3 (avirulence protein triggering Bs3 resistance) showed the functional interchangeability of DNA-binding and transcriptional activation domains. PCR was used to determine the sequence of brg11 homologs from strains infecting phylogenetically diverse host plants. Brg11 localizes to the nucleus and activates promoters containing a matching effector-binding element (EBE). Brg11 and homologs preferentially activate promoters containing EBEs with a 5' terminal guanine, contrasting with the TALE preference for a 5' thymine. Brg11 and other RipTALs probably promote disease through the transcriptional activation of host genes. Brg11 and the majority of homologs identified in this study were shown to activate similar or identical target sequences, in contrast to TALEs, which generally show highly diverse target preferences. This information provides new options for the engineering of plants resistant to R. solanacearum.
authors.affiliation: Genetics, Department of Biology I, Ludwig-Maximilians-University Munich, Martinsried, Germany.
authors.forename: Orlando
authors.initials: O
authors.lastname: de Lange
authors.forename: Tom
authors.initials: T
authors.lastname: Schreiber
authors.forename: Niklas
authors.initials: N
authors.lastname: Schandry
authors.forename: Jara
authors.initials: J
authors.lastname: Radeck
authors.forename: Karl Heinz
authors.initials: KH
authors.lastname: Braun
authors.forename: Julia
authors.initials: J
authors.lastname: Koszinowski
authors.forename: Holger
authors.initials: H
authors.lastname: Heuer
authors.forename: Annett
authors.initials: A
authors.lastname: Strauß
authors.forename: Thomas
authors.initials: T
authors.lastname: Lahaye
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D002467:Cell Nucleus / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D060467:Disease Resistance / Q000235:genetics*; D017343:Genes, Plant / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D058507:Host Specificity / Q000235:genetics; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology*; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D043368:Ralstonia solanacearum / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial
keywords: AvrBs3 (avirulence protein triggering Bs3 resistance); Brg11(hrpB-regulated 11); GMI1000; Ralstonia solanacearum; Ralstonia transcription activator-like effector (TALE)-like (RTL); designer transcription activator-like effector (TALE); repeat variable diresidue (RVD); transcription activator-like (TAL) effectors