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.