A glycoproteomics study of Xanthomonas citri subsp. citri

MALENA LANDONI; CARRAU ANALÍA; ORELLANO ELENA; COUTO ALICIA

San Martin, Buenos Aires

Simposio; 3er Simposio Argentino de Glicobiología; 2019

Sociedad Argentina de Glicobiología

Xanthomonas citri subsp. citri (Xcc) is a Gram-negative bacterium that produces citrus canker, a disease that affects all citrus commercial varieties. Light is an important environmental signal for all organisms that is perceived by photoreceptor proteins that translate this physical stimulus into a biochemical response. The Xcc genome has been completely sequenced. It presents three genes encoding for putative blue light receptors. Protein glycosylation is a post-translational modification essential to modulate protein structure and function. Glycans participate 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 the bacteria was grown in darkness. Some of these proteins are directly involved in the pathogenic mechanism, participating in the motility, mediated by the type IV pili, exopolisaccharide production and secretion systems II and IV. This result indicates that darkness induces the modification of a larger number of proteins glycosylated with high-mannose type oligosaccharides.