Flagellin glycosylation in Ralstonia solanacearum and its role in virulence

LANDONI, MALENA; TONDO, M. LAURA; VANDECAVEYE, AGUSTINA; ORELLANO, ELENA G.; COUTO, ALICIA

San Martin, Buenos Aires, Argentina

Simposio; 3rd Argentinian Symposium on Glycobiology; 2019

Universidad Nacional de San Martin

The addition of carbohydrates to flagellin, structural subunit of the bacterial flagellum, has been reported in Gram-negative bacteria, being in many cases required for the assembly, stability and functionality of the flagellar filament. In the case of pathogenic bacteria, it has been shown to play an essential role in virulence and in the evasion of host immune responses. Ralstonia solanacearum (Rso) is the causal agent of the destructive bacterial wilt disease in more than 200 plant species, including numerous crops of agronomic interest. The aim of this work was to characterize the glycosylation of the flagellin protein of Rso and to initiate the functional study of the RSp0387 and RSp0388 genes, encoding putative glycosyltransferases in the flagellar gene cluster. Flagellin protein was extracted from liquid cultures, identified by HPLC-ESI analysis, and its glycosylation pattern was characterized by mass spectrometry and HPAEC-PAD, determining the presence of N- and O-glycans of 3 to 14 units of hexose. Rso Rsp0387 and Rsp0388 deletion mutants were generated and physiologically characterized. The mutant strains exhibited normal flagellar structures under TEM microscopy but reduced motility in swimming plates and significant differences in autoagglutination assays compared to the WT strain. Moreover, differences were observed among the disease progress curves of the strains during tomato (Solanum lycopersicum) infection assays.