title: TALE1 from Xanthomonas axonopodis pv. manihotis acts as a transcriptional activator in plant cells and is important for pathogenicity in cassava plants.
abstract: Many plant-pathogenic bacteria suppress pathogen-associated molecular pattern (PAMP)-triggered immunity by injecting effector proteins into the host cytoplasm during infection through the type III secretion system (TTSS). This type III secretome plays an important role in bacterial pathogenicity in susceptible hosts. Xanthomonas axonopodis pv. manihotis (Xam), the causal agent of cassava bacterial blight, injects several effector proteins into the host cell, including TALE1(Xam) . This protein is a member of the Transcriptional Activator-Like effector (TALE) protein family, formerly known as the AvrBs3/PthA family. TALE1(Xam)  has 13.5 tandem repeats of 34 amino acids each, as well as two nuclear localization signals and an acidic activation domain at the C-terminus. In this work, we demonstrate the importance of TALE1(Xam)  in the pathogenicity of Xam. We use versions of the gene that lack different domains in the protein in structure-function studies to show that the eukaryotic domains at the 3' end are critical for pathogenicity. In addition, we demonstrate that, similar to the characterized TALE proteins from other Xanthomonas species, TALE1(Xam)  acts as a transcriptional activator in plant cells. This is the first report of the identification of a TALE in Xam, and contributes to our understanding of the pathogenicity mechanisms employed by this bacterium to colonize and cause disease in cassava.
authors.affiliation: Departamento de Ciencias Biológicas, Laboratorio de Micología y Fitopatología, Universidad de Los Andes, Bogota, DC, Colombia.
authors.forename: Luisa F
authors.initials: LF
authors.lastname: Castiblanco
authors.forename: Juliana
authors.initials: J
authors.lastname: Gil
authors.forename: Alejandro
authors.initials: A
authors.lastname: Rojas
authors.forename: Daniela
authors.initials: D
authors.lastname: Osorio
authors.forename: Sonia
authors.initials: S
authors.lastname: Gutiérrez
authors.forename: Alejandra
authors.initials: A
authors.lastname: Muñoz-Bodnar
authors.forename: Alvaro L
authors.initials: AL
authors.lastname: Perez-Quintero
authors.forename: Ralf
authors.initials: R
authors.lastname: Koebnik
authors.forename: Boris
authors.initials: B
authors.lastname: Szurek
authors.forename: Camilo
authors.initials: C
authors.lastname: López
authors.forename: Silvia
authors.initials: S
authors.lastname: Restrepo
authors.forename: Valérie
authors.initials: V
authors.lastname: Verdier
authors.forename: Adriana J
authors.initials: AJ
authors.lastname: Bernal
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D056426:Genetic Loci / Q000235:genetics; D002365:Manihot / Q000166:cytology* / Q000382:microbiology*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D059828:Plant Cells / Q000378:metabolism* / Q000382:microbiology; D010957:Plasmids / Q000235:genetics; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D053532:Xanthomonas axonopodis / Q000378:metabolism* / Q000472:pathogenicity*
chemical_list: D001426:Bacterial Proteins; D015534:Trans-Activators