A glycoproteomics study of Xanthomonas citri subsp. citri

LANDONI M. ; CARRAU A. ; ORELLANO E.G. ; COUTO A.S

Buenos Aires

Congreso; III Glycoar; 2019

Sociedad Argentina de glicobiología

Xanthomonas citri subsp. citri (Xcc) is a Gram-negative bacterium that produces citrus canker, a disease affecting all citrus varieties. Light is an important environmental signal that is perceived by photoreceptor proteins that translate this physical stimulus into a biochemical response. The Xcc genome has been sequenced. It presents three genes encoding for putative blue light receptors. Protein glycosylation participates in the pathogenic processes, motility, biofilm formation, cell-cell interaction and immune system evasion. In the present work, a glycoproteomic study of Xcc was performed for the first time. An SDS-PAGE analysis showed differences in the glycoprotein profile when the bacteria was grown in darkness or white light. Glycoproteins obtained from the bacteria grown under both conditions were enriched by a Con-A chromatography step and after trypsin digestion an HPLC-ESI-Orbitrap analysis was conducted. Raw data were processed by MaxQuant and Perseus packages for protein identification and statistical analysis. Interestingly, from the 417 glycoproteins identified, 14 were present exclusively when the bacterium was grown under white light while 110, exclusively when it was grown in darkness. Some of these proteins are involved in the pathogenic mechanism, participating in the motility, exopolysaccharide production and secretion systems II and IV. This result indicates that darkness induces glycosylation of proteins with high-mannose type oligosaccharides.