Protein O-linked glycosylation in the plant pathogen Ralstonia solanacearum

ELHENAWY, WAEL; SCOTT, NICHOLLAS E.; TONDO, M. LAURA; ORELLANO, ELENA G.; FOSTER, LEONARD; FELDMAN, MARIO F.

GLYCOBIOLOGY

OXFORD UNIV PRESS INC

Lugar: Oxford; Año: 2015

0959-6658

Ralstonia solanacearum is one of the most lethalphytopathogens in the world. Due to its broad host range, it can cause wiltingdisease in many plant species of economic interest. In this work, we identifiedthe O-oligosaccharyltransferase (O-OTase) responsible for proteinO-glycosylation in R. solanacearum. An analysis of the glycoproteome revealedthat 20 proteins, including type IV pilins are substrates of this general glycosylationsystem. Although multiple glycan forms were identified, the majority of theglycopeptides were modified with a pentasaccharide composed of HexNAc-(Pen)-dHex3, similar to the O antigen subunit present in the lipopolysaccharide ofmultiple R. solanacearum strains. Disruption of the O-OTase led to the totalloss of protein glycosylation, together with a defect in biofilm formation andreduced pathogenicity towards tomato plants. Comparative proteomic analysisrevealed that the loss of glycosylation is not associated with widespreadproteome changes. Only the levels of a single glycoprotein, the type IV pilin,were diminished in the absence of glycosylation. In parallel, disruption ofglycosylation triggered an increase in the levels of a surface lectinhomologous to Pseudomonas PA-IIL. These results reveal the important role ofglycosylation in the pathogenesis of R. solanacearum.