The Xanthomonas citri effector protein PthA interacts with citrus proteins involved in nuclear transport, protein folding and ubiquitination associated with DNA repair

Author(s)

Domingues, Mariane Noronha ^[1] ; de Souza, Tiago Antonio ^[1] ; Cernadas, Raul Andres ^[1] ; Peixoto de Oliveira, Maria Luiza ^[1] ; Docena, Cassia ^[2] ; Farah, Chuck Shaker ^[2] ; Benedetti, Celso Eduardo ^[1]

Affiliation

^[1] Ctr Nacl Pesquisa Energia & Mat, Lab Nacl Biociencias, BR-6192 Campinas, SP - Brazil

^[2] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-05508000 Sao Paulo - Brazil

• Document type: Journal article
• Source: MOLECULAR PLANT PATHOLOGY; v. 11, n. 5, p. 663-675, SEP 2010.
• Web of Science Citations: 23

Abstract

P>Xanthomonas axonopodis pv. citri utilizes the type III effector protein PthA to modulate host transcription to promote citrus canker. PthA proteins belong to the AvrBs3/PthA family and carry a domain comprising tandem repeats of 34 amino acids that mediates protein-protein and protein-DNA interactions. We show here that variants of PthAs from a single bacterial strain localize to the nucleus of plant cells and form homo- and heterodimers through the association of their repeat regions. We hypothesize that the PthA variants might also interact with distinct host targets. Here, in addition to the interaction with alpha-importin, known to mediate the nuclear import of AvrBs3, we describe new interactions of PthAs with citrus proteins involved in protein folding and K63-linked ubiquitination. PthAs 2 and 3 preferentially interact with a citrus cyclophilin (Cyp) and with TDX, a tetratricopeptide domain-containing thioredoxin. In addition, PthAs 2 and 3, but not 1 and 4, interact with the ubiquitin-conjugating enzyme complex formed by Ubc13 and ubiquitin-conjugating enzyme variant (Uev), required for K63-linked ubiquitination and DNA repair. We show that Cyp, TDX and Uev interact with each other, and that Cyp and Uev localize to the nucleus of plant cells. Furthermore, the citrus Ubc13 and Uev proteins complement the DNA repair phenotype of the yeast Delta ubc13 and Delta mms2/uev1a mutants, strongly indicating that they are also involved in K63-linked ubiquitination and DNA repair. Notably, PthA 2 affects the growth of yeast cells in the presence of a DNA damage agent, suggesting that it inhibits K63-linked ubiquitination required for DNA repair. (AU)

• FAPESP's process: 07/06686-0 - Characterization of protein-protein interactions between Xanthomonas axonopodis pv citri PthA and Citrus sinensis proteins
• Grantee: Celso Eduardo Benedetti
• Support type: Regular Research Grants
• FAPESP's process: 00/10266-8 - A structural biology laboratory network for the study of the 3D structures of proteins
• Grantee: Nilson Ivo Tonin Zanchin
• Support type: Genome Research Grants
• FAPESP's process: 98/14138-2 - Center for Structural Molecular Biotechnology
• Grantee: Glaucius Oliva
• Support type: Research Grants - Research, Innovation and Dissemination Centers - RIDC