A general protein O-glycosylation machinery conserved in Burkholderia species improves bacterial fitness and elicits glycan immunogenicity in humans

Yasmine Fathy Mohamed, Nichollas E. Scott, Antonio Molinaro, Carole Creuzenet, Ximena Ortega, Ganjana Lertmemongkolchai, Michael M. Tunney, Heather Green, Andrew M. Jones, David DeShazer, Bart J. Currie, Leonard J. Foster, Rebecca Ingram, Cristina De Castro, Miguel A. Valvano

Research output: Contribution to journalArticlepeer-review

Abstract

The Burkholderia genus encompasses many Gram-negative bacteria living in the rhizosphere. Some Burkholderia species can cause life-threatening human infections, highlighting the need for clinical interventions targeting specific lipopolysaccharide proteins. Burkholderia cenocepacia O-linked protein glycosylation has been reported, but the chemical structure of the O-glycan and the machinery required for its biosynthesis are unknown and could reveal potential therapeutic targets. Here, using bioinformatics approaches, gene-knockout mutants, purified recombinant proteins, LC-MS-based analyses of O-glycans, and NMR-based structural analyses, we identified a B. cenocepacia O-glycosylation (ogc) gene cluster necessary for synthesis, assembly, and membrane translocation of a lipid-linked O-glycan, as well as its structure, which consists of a β-Gal-(1,3)-α-GalNAc-(1,3)-β-GalNAc trisaccharide. We demonstrate that the ogc cluster is conserved in the Burkholderia genus, and we confirm the production of proteins with similar glycans in the Burkholderia species: B. thailandensis, B. gladioli, and B. pseudomallei. Furthermore, we show that absence of protein O-glycosylation severely affects bacterial fitness and accelerates bacterial clearance in a Galleria mellonella larva infection model. Finally, our experiments revealed that patients infected with B. cenocepacia, Burkholderia multivorans, B. pseudomallei, or Burkholderia mallei develop O-glycan-specific antibodies. Together, these results highlight the importance of general protein O-glycosylation in the biology of the Burkholderia genus and its potential as a target for inhibition or immunotherapy approaches to control Burkholderia infections.

Original languageEnglish
Pages (from-to)13248-13268
Number of pages21
JournalJournal of Biological Chemistry
Volume294
Issue number36
Early online date26 Jul 2019
DOIs
Publication statusPublished - 6 Sept 2019

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