Identification of o-linked protein glycosylation system in Ralstonia solanacearum

ELHENAWY W.; SCOTT N.E.; TONDO, M.L.; ORELLANO, E.G.; FELDMAN M.F.

Canmore

Simposio; 10th Annual National Carbohydrate Symposium of the Alberta Glycomics Centre; 2014

Ralstonia solanacearum is a prominent plant pathogen known to infect a wide range of crops. R. solanacearum causes wilt disease leading to economical losses in the agricultural sector worldwide. Our in-silico analysis suggested the presence of a putative protein O-glycosylation system in R. solanacearum. The O-glycosylation machinery was shown to be important for virulence in different bacteria. While some bacteria utilize cytoplasmic glycosyl transferases to sequentially decorate their proteins with sugars, others rely on an O-oligosaccharyl transferase to glycosylate their proteins via en-bloc transfer of glycans in the periplasm. In this work, we used mass spectrometry to identify the glycoproteins of R.solanacearum. Our MS analysis revealed the presence of many glycoproteins with different glycans linked to their serine or threonine residues via O-glycosylation. Among these glycoproteins is the type IV pilin known to be important in biofilm formation and twitching motility. Furthermore, we identified the O-oligosaccharyl transferase (O-Otase) in R. solanacearum and demonstrated its activity in vivo. Knocking down the Ralstonia O-Otase resulted in the loss of protein O-glycosylation as well as a significant decrease in virulence in tomato plant model. Our data suggests an important role of O-glycosylation in R. solanacearum which can be a novel target for new treatments.