Dissecting bacterial ligands for lectins: from isolated molecules to the entire pathogen surface
| Autor: | Kalograiaki, Ioanna, Euba, Begoña, Proverbio, Davide, Aastrup, Teodor, Garmendia, Juncal, Cañada, F. Javier, Solís, Dolores |
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| Přispěvatelé: | European Commission, Centro de Investigación Biomédica en Red Enfermedades Respiratorias (España), Instituto de Salud Carlos III, Ministerio de Economía y Competitividad (España) |
| Rok vydání: | 2017 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 2011-2890 |
| Popis: | Trabajo presentado en el 19th European Carbohydrate Symposium EuroCarb, celebrado en Barcelona (España), del 2 al 6 de julio de 2017 Bacterial glycocalyx components are intimately associated with virulence and commonly used for strain typification. Up until recently, analysis of their recognition by lectins and antibodies was commonly performed following isolation of selected constituents from the pathogen surface. Of note, in these ligand-targeted approaches, the natural presentation and accessibility of glycans along with possible cooperativity of neighbour molecules are not considered, an aspect particularly relevant in the case of weak binders. We recently developed a combined approach of static microarrays and QCM biosensor assays under flow, based on the use of entire bacteria, and demonstrated its usefulness for detection and real-time monitoring of lectin recognition processes [1]. We benefitted from the availability of a panel of nontypeable Heamophilus influenzae (strain NTHi375) mutants, defective for selected lipooligosaccharide (LOS)-specific enzymes, and focused our studies on the effect of LOS truncation in lectin binding to the bacteria. Intriguingly, LOS truncation gave rise to distinct binding profiles for Viscum album and Ricinus communis agglutinins, pointing to the recognition of different Gal-bearing targets. Besides the LOS molecule, a variety of glycoconjugates can be present at the bacterial surface, also encompassing glycoproteins of great significance in pathogenesis. In particular, in NTHi375, hmw loci code for two heavily glycosylated adhesins that are absent in other NTHi strains, as e.g. Rd KW20, a noninvasive laboratory strain. In this work, we pursued the dissection of bacterial surface ligands recognised by these two lectins. To this aim, we comparatively examined their binding to NTHi375, an NTHi375Δomp5 mutant suspected to overexpress LOS, Rd KW20, and an isogenic Rd KW20 mutant expressing HMW1, using our combined bacteria-based microarray and QCM approach. In parallel, recognition of the isolated NTHi375 and Rd KW20 LOSs, whose structures are known to be different, was also examined using LOS-based microarrays. Furthermore, saturation transfer difference NMR experiments allowed the identification of the sugar residues involved in the recognition. Altogether, the results revealed strain- and lectin-specific binding patterns, from the level of LOS molecules to the intact bacterial surface. This work was supported by the Marie Curie Initial Training Networks DYNANO (PITN-GA-2011-289033), GLYCOPHARM (PITN-GA-2012-317297) and WntsApp (PITN-GA-2013- 608180), the CIBER of Respiratory Diseases (CIBERES) – an initiative from the Spanish Institute of Health Carlos III (ISCIII), and the Spanish Ministry of Economy and Competitiveness (grants CTQ2015-64597-C2- 2-P, BFU2012-36825, BFU2015-70052-R, SAF2012-31166 and SAF2015-66520-R). I.K. was funded by a Marie Curie contract from the European Commission. |
| Databáze: | OpenAIRE |
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