An acquired bacterial plant natriuretic peptide-like protein modifies host homeostasis

GOTTIG N; GARAVAGLIA BS; DAURELIO LD; ORELLANO EG; OTTADO J

Carlos Paz, Córdoba, Argentina.

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Plant natriuretic peptides (PNPs) are a class of extracellular, systemically mobile peptides that elicit a number of plant responses important in homeostasis and growth. The bacterial citrus pathogen Xanthomonas axonopodis pv. citri (Xac) also contains a gene encoding a PNP-like protein, XacPNP, that shares significant sequence similarity and identical domain organization with PNPs but has no homologues in other bacteria. We have expressed and purified XacPNP and demonstrated that the bacterial protein, like PNPs, could alter plant physiological responses. We also observed that XacPNP transcription can respond to the host environment suggesting a role during bacterial infection. To characterize the role of XacPNP in citrus canker, we constructed a XacPNP deletion mutant. The lesions caused by this mutant were more necrotic than those observed with the wild-type and bacterial cell death occurred earlier in the mutant. Moreover, when we expressed XacPNP in Xanthomonas axonopodis pv. vesicatoria, the transgenic bacteria caused less necrotic lesions in the host than the wild-type. We have evidence to conclude that XacPNP enables Xac to modify host homeostasis in order to create conditions favorable to its own survival.