Celso Eduardo Benedetti
Phone: +55 19 3512.1267
Our research focuses on how plant bacterial pathogens survive and cause disease in the host plant and how plants defend themselves against them. In particular, we are studying the structure and function of proteins from the citrus bacterial pathogens Xanthomonas citri and Xylella fastidiosa that play roles in pathogenicity or adaptation, as well as the structure and function of sweet orange proteins involved in symptom development or disease resistance.
Functional analysis of bacterial TAL effectors
TAL effectors are bacterial proteins that function as transcriptional activators in the plant cell. We are studying the biological roles played by TAL effectors from the citrus canker pathogens Xanthomonas citri and Xanthomonas aurantifolii in sweet orange and other citrus plants. Since these bacterial pathogens utilize several TAL effectors to cause disease and/or suppress plant defenses, we are investigating the contribution of each effector protein in canker development and pathogen growth. Our interest is to unravel how TAL effectors modulate transcription in the host and what are their target genes.
Structural and functional analysis of citrus proteins involved in citrus canker development
We have identified several sweet orange proteins as direct targets of the Xanthomonas TAL effectors. Some of these proteins are involved in biological processes such as transcription regulation, mRNA stabilization and translational control. In particular, we are characterizing the function of two citrus proteins that play roles as negative regulators of transcription mediated by the RNA polymerases II and III.
Structural and functional analysis of bacterial proteins that control hydrogen sulfide detoxification
Hydrogen sulfide, which is produced as a byproduct of the bacterial metabolism, is a potent inhibitor of aerobic respiration. Since the bacterial pathogens Xylella fastidiosa and Agrobacterium tumefaciens are obligate aerobic organisms and colonize plant tissues that have low oxygen levels, for instance the vascular tissues, the bacteria cannot accumulate hydrogen sulfide. We found that the both Xylella and Agrobacterium cells require a set of proteins to detoxify hydrogen sulfide under limited oxygen conditions. Now we are studying the structure and function of each of these proteins to understand how hydrogen sulfide is possibly converted into sulfite and how sulfite is exported by the cells.
Development of citrus plants with increased resistance against bacterial pathogens
We have identified through global transcriptional analysis a number of sweet orange genes that are involved in the resistance response against Xanthomonas pathogens. These genes have been cloned and expressed in sweet orange and other citrus varieties as a mean to obtain increased resistance against X. citri, the causal agent of citrus canker.
Domingues MN, Campos BM, de Oliveira MLP, de Mello UQ, Benedetti CE (2012) TAL Effectors Target the C-Terminal Domain of RNA Polymerase II (CTD) by Inhibiting the Prolyl-Isomerase Activity of a CTD-Associated Cyclophilin. PLoS One. 2012;7(7):e41553
de Souza TA, Soprano AS, de Lira NP, Quaresma AJ, Pauletti BA, Paes Leme AF, Benedetti CE. (2012) The TAL Effector PthA4 Interacts with Nuclear Factors Involved in RNA-Dependent Processes Including a HMG Protein That Selectively Binds Poly(U) RNA. PLoS One 7(2): e32305.
Guimarães BG, Barbosa RL, Soprano AS, Campos BM, de Souza TA, Tonoli CC, Leme AF, Murakami MT, Benedetti CE. (2011) Plant Pathogenic Bacteria Utilize Biofilm Growth-associated Repressor (BigR), a Novel Winged-helix Redox Switch, to Control Hydrogen Sulfide Detoxification under Hypoxia. J Biol Chem. 286: 26148-26157
Murakami MT, Sforça M, Neves J, Paiva J, Domingues MN, Pereira ALA, Zeri AC, Benedetti CE (2010). The repeat domain of the type III effector protein PthA shows a TPR-like structure and undergoes conformational changes upon DNA interaction. Proteins 78: 3386–3395
Domingues MN, Souza TA, Cernadas RA, de Oliveira MLP, Docena C, Farah CS and Benedetti CE (2010) The Xanthomonas citri effector protein PthA interacts with citrus proteins involved in nuclear transport, protein folding and ubiquitination associated with DNA repair. Mol Plant Pathol 11(5): 663-675
Cernadas RA and Benedetti CE (2009) Auxin and Gibberellin-mediated expression of cell wall remodeling genes induced by Xanthomonas axonopodis pv citri. Plant Science 177: 190-195
Cernadas RA, Camillo LR, Benedetti CE (2008) Transcriptional analysis of the sweet orange interaction with the citrus canker pathogens Xanthomonas axonopodis pv. citri and Xanthomonas axonopodis pv. aurantifolii. Mol Plant Pathol 9(5): 609-631
Vanini MMT, Sforça ML, Spisni A, Pertinhez TA, Benedetti CE (2008) The solution structure of the outer membrane lipoprotein OmlA from Xanthomonas axonopodis pv. citri reveals a protein fold implicated in protein-protein interaction. Proteins 71(4):2051-64
Barbosa RL, Benedetti CE (2007) BigR, a Transcriptional Repressor from Plant-Associated Bacteria, Regulates an Operon Implicated in Biofilm Growth. J Bacteriol 189: 6185-94
1988 – Graduated in Biological Sciences at the State University of Campinas
1991 – Master degree in Plant Biology at the State University of Campinas
Title: Electrophoretic analysis of membrane proteins from the grass pathogens Pseudomonas avenae and Pseudomonas rubrilineans.
1995 – PhD degree in Plant Molecular Biology at the University of East Anglia – UK
Title: Isolation and characterization of Arabidopsis thaliana mutants resistant to the phytotoxin coronatine
1995 – 2000 Postdoctoral fellow, State University of Campinas
2000 – 2001 Postdoctoral fellow, National Laboratory of Biosciences