Structural and conformational study of the O‐antigenic portion of the Lipopolysaccharide isolated from Burkholderia gladioli pv. cocovenenans.
(2016) Structural and conformational study of the O‐antigenic portion of the Lipopolysaccharide isolated from Burkholderia gladioli pv. cocovenenans. Eur J Org Chem 4, 748-755.
Lipopolysaccharides (LPSs) are virulence factors thatare expressed on the cell surface of Gram-negative bacteria.They represent one of the main traits of bacterial virulence. Inthis paper, we report the primary structure and the conforma-tional features of the O-chain from the lipopolysaccharide (LPS)produced by Burkholderia gladioli pv. cocovenenans, a bacte-rium often associated with the mucoralean fungus Rhizopusmicrosporus var. oligosporus, which is traditionally used in foodfermentations. With the aim of understanding the organizationof bacterial cell-surface components, we isolated and character-ized the following O-antigenic portions of the LPS from B. gladi-IntroductionBurkholderia sp. are ubiquitous Gram-negative motile obligateaerobic rod-shaped bacteria that have the unique ability toadapt to and survive in many different environments. Burkhold-eria gladioli pv. cocovenenans (BGC), which has been isolatedfrom cultures of the mucoralean fungus Rhizopus microsporusvar. oligosporus, plays a key role in the context of plant disease,agriculture, and food processing. The Rhizopus microsporusgroup consists of various taxa, which are responsible for toxinproduction and pathogenesis,[1,2]and which have caused sev-eral lethal poisonings.R. microsporus var. oligosporus is tradi-tionally used to prepare fermented foods such as tempe, a typi-cal Indonesian dish. However, its consumption has occasionallyled to severe poisoning due to the presence of bacterial con-taminants in the fungal starter culture.BGC,one such bac-terial contaminant, is responsible for producing the polyketidebongkrekic acid,a respiratory toxin that causes hyperglycae-mia followed by hypoglycaemia, and may cause the death ofthe consumer.[7,8]Bongkrekic acid is an unsaturated tricarbox-[a] Dipartimento di Chimica Organica e Biochimica, Università di NapoliFederico II, Complesso Universitario Monte S. Angelo,Via Cintia 4, 80126 Napoli, ItalyE-mail: email@example.com://chemicalsciences.unina.it/[b] Leibniz Institute for Natural Product Research and Infection Biology, HansKnöll Institute,07745 Jena, GermanySupporting information for this article is available on the WWW underhttp://dx.doi.org/10.1002/ejoc.201501308.Eur. J. Org. Chem. 2016, 748–755 © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim748oli pv. cocovenenans:[→2)-α-Rha-(1→2)-α-Aco-(1→2)-α-Rha-(1→4)-β-Gal2Me-(1→]nand [→2)-α-Rha-(1→2)-α-Aco-(1→2)-α-Rha-(1→4)-β-Gal-(1→]n. A distinctive feature of the O-chain isthe presence of methylated sugar residues. This contributes tothe creation of a hydrophobic shield. The experimental datawere confirmed by conformational studies, which showedthree-dimensional shapes with different packings and exten-sions. Such features determine the physicochemical propertiesof the bacterial envelope, and might contribute to the abilityto adapt the membrane surface to the host.
doi: DOI: 10.1002/ejoc.201501308