title: The TAL effector PthA4 interacts with nuclear factors involved in RNA-dependent processes including a HMG protein that selectively binds poly(U) RNA.
abstract: Plant pathogenic bacteria utilize an array of effector proteins to cause disease. Among them, transcriptional activator-like (TAL) effectors are unusual in the sense that they modulate transcription in the host. Although target genes and DNA specificity of TAL effectors have been elucidated, how TAL proteins control host transcription is poorly understood. Previously, we showed that the Xanthomonas citri TAL effectors, PthAs 2 and 3, preferentially targeted a citrus protein complex associated with transcription control and DNA repair. To extend our knowledge on the mode of action of PthAs, we have identified new protein targets of the PthA4 variant, required to elicit canker on citrus. Here we show that all the PthA4-interacting proteins are DNA and/or RNA-binding factors implicated in chromatin remodeling and repair, gene regulation and mRNA stabilization/modification. The majority of these proteins, including a structural maintenance of chromosomes protein (CsSMC), a translin-associated factor X (CsTRAX), a VirE2-interacting protein (CsVIP2), a high mobility group (CsHMG) and two poly(A)-binding proteins (CsPABP1 and 2), interacted with each other, suggesting that they assemble into a multiprotein complex. CsHMG was shown to bind DNA and to interact with the invariable leucine-rich repeat region of PthAs. Surprisingly, both CsHMG and PthA4 interacted with PABP1 and 2 and showed selective binding to poly(U) RNA, a property that is novel among HMGs and TAL effectors. Given that homologs of CsHMG, CsPABP1, CsPABP2, CsSMC and CsTRAX in other organisms assemble into protein complexes to regulate mRNA stability and translation, we suggest a novel role of TAL effectors in mRNA processing and translational control.
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP, Brazil.
authors.forename: Tiago Antonio
authors.initials: TA
authors.lastname: de Souza
authors.forename: Adriana Santos
authors.initials: AS
authors.lastname: Soprano
authors.forename: Nayara Patricia Vieira
authors.initials: NP
authors.lastname: de Lira
authors.forename: Alexandre José Christino
authors.initials: AJ
authors.lastname: Quaresma
authors.forename: Bianca Alves
authors.initials: BA
authors.lastname: Pauletti
authors.forename: Adriana Franco
authors.initials: AF
authors.lastname: Paes Leme
authors.forename: Celso Eduardo
authors.initials: CE
authors.lastname: Benedetti
mesh_terms: D017360:Arabidopsis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D002875:Chromosomes / Q000648:ultrastructure; D002957:Citrus; D004260:DNA Repair; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006609:High Mobility Group Proteins / Q000235:genetics; D016366:Open Reading Frames; D010936:Plant Extracts / Q000378:metabolism; D011072:Poly U / Q000737:chemistry*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry*; D012333:RNA, Messenger / Q000378:metabolism; D000071336:Transcription Activator-Like Effectors; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques; D014974:Xanthomonas / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D006609:High Mobility Group Proteins; D010936:Plant Extracts; C077723:PthA protein, Xanthomonas campestris; D012333:RNA, Messenger; D000071336:Transcription Activator-Like Effectors; D011072:Poly U; D012313:RNA