IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Structural analysis of Xanthomonas axonopodis pv. citri lipopolysaccharide
Autor/es:
A. S. COUTO; A. CASABUONO, ; S.PETROCELLI,; J.OTTADO; E. G. ORELLANO
Lugar:
Rotterdam
Reunión:
Congreso; 9th Eurofed Lipid Congress; 2011
Institución organizadora:
European Federation for the Science and Technology of Lipids
Resumen:
STRUCTURAL ANALYSIS OF XANTHOMONAS AXONOPODIS pv. CITRI LIPOPOLYSACCHARIDE Alicia S. Couto1, Adriana Casabuono1, Silvana Petrocelli2, Jorgelina Ottado2, Elena G. Orellano 2,3.  CIHIDECAR, Depto. de Química Orgánica, FCEN, (1428) UBA, Bs. As, Argentina; 2IBR-CONICET-UNR, 3CIUNR, UNR, Rosario, Argentina   Xanthomonas axonopodis pv. citri causes citrus canker, provoking defoliation and premature fruit drop with the concomitant economical damage. In plant pathogenic bacteria, lipopolysaccharides are important virulence factors and they are being increasingly recognized as major pathogen associated molecular patterns for plants. In general three domains are recognized in a lipopolysaccharide: the hydrophobic lipid A, the hydrophilic O-antigen polysaccharide and the core oligosaccharide, connecting lipid A and O-antigen. In this work we have determined the structure of purified lipopolysaccharides obtained from Xanthomonas axonopodis pv. citri wild type and a mutant of the O-antigen ABC transporter encoded by wzt gene. High pH anion exchange chromatography and matrix assisted laser desorption/ionization mass spectra analysis were performed enabling to determine the structure not only of the released oligosaccharides and lipid A moieties but also the intact lipopolysaccharides. The results demonstrate that Xac wild type and Xacwzt LPSs are composed mainly of a penta or tetra-acylated di-glucosamine backbone attached to either two pyrophosphorylethanolamine groups or one pyro- and one phosphoethanolamine groups. The core region consists in a branched oligosaccharide formed by Kdo2Hexose6GalA3Fuc3NAcRham4 and two phosphate groups. As expected, the presence of a rhamnose homooligosaccharide as O-Antigen was determined only in the wild Xac lipopolysaccharide. In addition, we have examined the lipopolysaccharides function from Xac in the pathogenesis process. We analyzed the response of the different lipopolysaccharides during the stomata aperture-closure cycle and in the callose deposition in citrus leaves suggesting a functional role of the O-antigen from Xac lipopolysaccharides in the basal response.