Burkholderia pseudomallei and Chromobacterium violaceum are bacteria of tropical and subtropical soil and water that occasionally cause fatal infections in humans and animals. Microbial lectins mediate the adhesion of organisms to host cells, which is the first phase in the development of infection. Here we report the discovery of two novel lectins from the above-mentioned bacteria - BP39L and CV39L. The crystal structures revealed that the lectins possess a seven-bladed β-propeller fold. Functional studies conducted on a series of oligo- and polysaccharides confirmed the preference of BP39L for mannosylated saccharides and CV39L for rather more complex polysaccharides with a monosaccharide preference for β-l-fucose. The presented data indicate that the proteins belong to a currently unknown family of lectins.
- MeSH
- bakteriální proteiny metabolismus MeSH
- Burkholderia pseudomallei metabolismus MeSH
- Chromobacterium metabolismus MeSH
- fukosa metabolismus MeSH
- lektiny metabolismus MeSH
- lidé MeSH
- monosacharidy metabolismus MeSH
- polysacharidy metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Lectins with a β-propeller fold bind glycans on the cell surface through multivalent binding sites and appropriate directionality. These proteins are formed by repeats of short domains, raising questions about evolutionary duplication. However, these repeats are difficult to detect in translated genomes and seldom correctly annotated in sequence databases. To address these issues, we defined the blade signature of the five types of β-propellers using 3D-structural data. With these templates, we predicted 3,887 β-propeller lectins in 1,889 species and organized this information in a searchable online database. The data reveal a widespread distribution of β-propeller lectins across species. Prediction also emphasizes multiple architectures and led to the discovery of a β-propeller assembly scenario. This was confirmed by producing and characterizing a predicted protein coded in the genome of Kordia zhangzhouensis. The crystal structure uncovers an intermediate in the evolution of β-propeller assembly and demonstrates the power of our tools.
- MeSH
- Archaea chemie MeSH
- Bacteria chemie MeSH
- databáze proteinů MeSH
- Eukaryota chemie MeSH
- genom bakteriální MeSH
- lektiny chemie MeSH
- molekulární modely MeSH
- multimerizace proteinu MeSH
- proteom MeSH
- sbalování proteinů MeSH
- sekundární struktura proteinů MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The Aspergillus fumigatus lectin AFL was recently described as a new member of the AAL lectin family. As a lectin from an opportunistic pathogen, it might play an important role in the interaction of the pathogen with the human host. A detailed study of structures of AFL complexed with several monosaccharides and oligosaccharides, including blood-group epitopes, was combined with affinity data from SPR and discussed in the context of previous findings. Its six binding sites are non-equivalent, and owing to minor differences in amino-acid composition they exhibit a marked difference in specific ligand recognition. AFL displays a high affinity in the micromolar range towards oligosaccharides which were detected in plants and also those bound on the human epithelia. All of these results indicate AFL to be a complex member of the lectin family and a challenging target for future medical research and, owing to its binding properties, a potentially useful tool in specific biotechnological applications.
- MeSH
- Aspergillus fumigatus chemie MeSH
- epitel MeSH
- fungální proteiny chemie MeSH
- lektiny chemie MeSH
- lidé MeSH
- oligosacharidy chemie MeSH
- terciární struktura proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Aspergillus fumigatus is an important allergen and opportunistic pathogen. Similarly to many other pathogens, it is able to produce lectins that may be involved in the host-pathogen interaction. We focused on the lectin AFL, which was prepared in recombinant form and characterized. Its binding properties were studied using hemagglutination and glycan array analysis. We determined the specificity of the lectin towards l-fucose and fucosylated oligosaccharides, including α1-6 linked core-fucose, which is an important marker for cancerogenesis. Other biologically relevant saccharides such as sialic acid, d-mannose or d-galactose were not bound. Blood group epitopes of the ABH and Lewis systems were recognized, Le(Y) being the preferred ligand among others. To provide a correlation between the observed functional characteristics and structural basis, AFL was crystallized in a complex with methyl-α,L-selenofucoside and its structure was solved using the SAD method. Six binding sites, each with different compositions, were identified per monomer and significant differences from the homologous AAL lectin were found. Structure-derived peptides were utilized to prepare anti-AFL polyclonal antibodies, which suggested the presence of AFL on the Aspergillus' conidia, confirming its expression in vivo. Stimulation of human bronchial cells by AFL led to IL-8 production in a dose-dependent manner. AFL thus probably contributes to the inflammatory response observed upon the exposure of a patient to A. fumigatus. The combination of affinity to human epithelial epitopes, production by conidia and pro-inflammatory activity is remarkable and shows that AFL might be an important virulence factor involved in an early stage of A. fumigatus infection.
- MeSH
- Aspergillus fumigatus chemie MeSH
- aspergilóza imunologie MeSH
- bronchy cytologie mikrobiologie MeSH
- epitopy chemie MeSH
- faktory virulence chemie MeSH
- fukosa chemie MeSH
- galaktosa chemie MeSH
- genom fungální MeSH
- hemaglutinace MeSH
- interakce hostitele a patogenu MeSH
- interleukin-8 metabolismus MeSH
- kyselina N-acetylneuraminová chemie MeSH
- lektiny chemie MeSH
- lidé MeSH
- mannosa chemie MeSH
- molekulární sekvence - údaje MeSH
- oligosacharidy chemie MeSH
- sekvence aminokyselin MeSH
- sekvenční homologie aminokyselin MeSH
- sekvenční seřazení MeSH
- spory hub chemie MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
The opportunistic pathogen Burkholderia cenocepacia expresses several soluble lectins, among them BC2L-C. This lectin exhibits two domains: a C-terminal domain with high sequence similarity to the recently described calcium-dependent mannose-binding lectin BC2L-A, and an N-terminal domain of 156 amino acids without similarity to any known protein. The recombinant N-terminal BC2L-C domain is a new lectin with specificity for fucosylated human histo-blood group epitopes H-type 1, Lewis b, and Lewis Y, as determined by glycan array and isothermal titration calorimetry. Methylselenofucoside was used as ligand to solve the crystal structure of the N-terminal BC2L-C domain. Additional molecular modeling studies rationalized the preference for Lewis epitopes. The structure reveals a trimeric jellyroll arrangement with striking similarity to TNF-like proteins, and to BclA, the spore protein from Bacillus anthracis which may play an important role in bioadhesion of anthrax spores in human lungs.
- MeSH
- antigeny krevních skupin chemie imunologie metabolismus MeSH
- bakteriální proteiny chemie metabolismus MeSH
- Burkholderia chemie metabolismus MeSH
- epitopy chemie imunologie metabolismus MeSH
- fukosa chemie metabolismus MeSH
- kvarterní struktura proteinů MeSH
- lektiny chemie metabolismus MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární sekvence - údaje MeSH
- sekvence aminokyselin MeSH
- sekvenční seřazení MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
