A glycoproteomics study of Xanthomonas citri subsp. Citri

LANDONI, M.; CARRAU, A; ORELLANO, EG; COUTO, AS

Buenos Aires

Simposio; 3rd Argentinian Symposium on Glycobiology GlycoAR 2019; 2019

Xanthomonas citri subsp. citri (Xcc) is a Gram-negativebacterium that produces citrus canker, a disease affecting allcitrus varieties. Light is an important environmental signal that isperceived by photoreceptor proteins that translate this physicalstimulus into a biochemical response. The Xcc genome has beensequenced. It presents three genes encoding for putative bluelight receptors. Protein glycosylation participates in thepathogenic processes, motility, biofilm formation, cell-cellinteraction and immune system evasion. In the present work, aglycoproteomic study of Xcc was performed for the first time. AnSDS-PAGE analysis showed differences in the glycoproteinprofile when the bacteria was grown in darkness or white light.Glycoproteins obtained from the bacteria grown under bothconditions were enriched by a Con-A chromatography step andafter trypsin digestion an HPLC-ESI-Orbitrap analysis wasconducted. Raw data were processed by MaxQuant and Perseuspackages for protein identification and statistical analysis.Interestingly, from the 417 glycoproteins identified, 14 werepresent exclusively when the bacterium was grown under whitelight while 110, exclusively when it was grown in darkness. Someof these proteins are involved in the pathogenic mechanism,participating in the motility, exopolysaccharide production andsecretion systems II and IV. This result indicates that darknessinduces glycosylation of proteins with high-mannose typeoligosaccharides.