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Weed pollen allergens
Published in Richard F. Lockey, Dennis K. Ledford, Allergens and Allergen Immunotherapy, 2020
Michael Hauser, Gabriele Gadermaier, Sabrina Wildner, Lisa Pointner, Michael Wallner, Fatima Ferreira
In contrast to the dominant IgE-binding activity of Amb a 1, only 26% sensitization prevalence was found for Art v 6, the homologous pectate lyase in mugwort pollen [15]. A study demonstrated that Art v 6 elicits less diverse IgE and T-cell responses than Amb a 1, even though Art v 6 shares 65% sequence identity with Amb a 1 [16]. In a further study, a hybrid molecule consisting of the α-chains of Amb a 1 and Art v 6 was designed, expressed in Escherichia coli, and purified to homogeneity. This accumulation of T-cell epitopes and deletion of IgE-reactive areas of the two allergens modulated the immunologic properties of the hybrid, leading to a promising novel candidate for therapeutic approaches [17]. Nevertheless, primary sensitization to Art v 6, which is commonly observed in areas with high mugwort pollen exposure, may also play a role in the development of cross-sensitization to Amb a 1. This was further investigated in enzyme-linked immunosorbent assay (ELISA) and ELISA inhibition experiments with clinically relevant pectate lyase allergens Amb a 1 and Art v 6, as well as tree pollen pectate lyase allergens from cypress and Japanese cedar (Cup a 1, Jun a 1, and Cry j 1) using serum samples from various cohorts. Results showed specific sensitization patterns for each geographic region, which reflected the natural allergen exposure of the patients. Significant cross-reactivity was found between the plant orders (Asteraceae and Cupressaceae); however, cross-reactivity was limited between the orders [18].
The Genetics of the Frankia-Actinorhizal Symbiosis
Published in Peter M. Gresshoff, Molecular Biology of Symbiotic Nitrogen Fixation, 2018
Pascal Simonet, Philippe Normand, Ann M. Hirsch, Antoon D. L. Akkermans
It is likely that Frankia could invade host roots using a biochemical process similar to that used by phytopathogenic bacteria. Indeed, many of the steps used by pathogenic and symbiotic organisms to invade the plant appear similar superficially. Pathogens produce pectate lyase which breaks down the middle lamella and primary cell wall of plant tissues.114 The genes coding for pectate lyase enzymes from Erwinia chrysanthemi, an enterobacterium pathogenic on many plants115 which produces various pectinases, cellulases, and proteases,116,117 have been cloned.118-120 Simonet et al.58a have found that Frankia DNA sequences exhibited sequence similarity to Erwinia genes coding for pectate lyase. They found that a great deal of sequence similarity exists between Frankia and E. chrysanthemi pel genes on the basis of hybridization intensity. The intensity of the heterologous hybridization band decreased only under conditions of high stringency. Frankia DNA exhibited a greater degree of hybridization to a pelA clone than to a pelD gene.
Serine-rich repeat proteins from gut microbes
Published in Gut Microbes, 2020
Dimitrios Latousakis, Donald A. MacKenzie, Andrea Telatin, Nathalie Juge
In L. reuteri, the SecA2/Y2 cluster and SRRP in the murine isolate L. reuteri 100-23 is crucial for adhesion of the bacteria to the forestomach epithelium of the murine GI tract, as shown by colonization experiments in germ-free mice with L. reuteri 100-23 wild-type and mutants.17 Mutants lacking the secA2 gene showed defective adhesion, whereas mutants lacking srrp showed the most reduced biofilm formation, compared to other putative adhesins tested.17 In contrast to all structurally characterized SRRP-BRs reported to date, L. reuteri SRRP-BR displays a fold typically adopted by extracellular pectate lyase PelC-like proteins.18 The BR crystal structures of SRRP100-23 and SRRP53608 from L. reuteri ATCC 53608, revealed a “β-solenoid” fold comprising β-strands coiled in a repetitive pattern to form a right-handed helix with three parallel β-sheets, which is unique in the SRRP family.18