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2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid

BACKGROUND: Dolichos biflorus agglutinin (DBA) is a lectin with a binding specificity toward α-linked N-acetylgalactosamine (α-GalNAc). While DBA is known to bind some, but not all, pneumococci, its target molecule has not been identified. Pneumococcus teichoic acid (TA) and lipoteichoic acid (LTA)...

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Autores principales: Zhou, Meng-Lan, Frost, Michael R, Nahm, Moon H
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6809722/
http://dx.doi.org/10.1093/ofid/ofz360.2275
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author Zhou, Meng-Lan
Frost, Michael R
Nahm, Moon H
author_facet Zhou, Meng-Lan
Frost, Michael R
Nahm, Moon H
author_sort Zhou, Meng-Lan
collection PubMed
description BACKGROUND: Dolichos biflorus agglutinin (DBA) is a lectin with a binding specificity toward α-linked N-acetylgalactosamine (α-GalNAc). While DBA is known to bind some, but not all, pneumococci, its target molecule has not been identified. Pneumococcus teichoic acid (TA) and lipoteichoic acid (LTA) have repeating units with α-GalNAc-(1→3)β-GalNAc decorated with phosphorylcholine (PC) at the O-6 positions. Two PC transferases, LicD1 and LicD2, mediate the attachment of PC to GalNAc residues while phosphorylcholine esterase (Pce) removes PCs attached to the terminal GalNAcs. We examined if DBA binds to the terminal α-GalNAc-(1→3)β-GalNAc created by Pce. METHODS: Fifteen pneumococcus strains expressing 14 different serotypes, including one non-encapsulated strain (R36A), were studied with flow cytometry (FC) and confocal fluorescence microscopy (CFM) for DBA binding. Pce enzyme activity was detected with a colorimetric assay using p-nitrophenyl-phosphorylcholine as the substrate. Mutant strains with pce knocked-out were constructed in R36A and D39 by replacing pce with Janus cassette. Both licD genes were sequenced for some of the strains. RESULTS: Ten of the 15 strains had Pce activity and all of them bound DBA (Table 1). When the pce gene was inactivated in two normally Pce-positive strains (R36A(△pce) and D39(△pce)), the strains did not show DBA binding by CFM (Figure 1). Thus, expression of Pce appears to be sufficient for expressing the DBA antigen. Of the five strains that had no Pce activity, two bound DBA. Sequencing of the licD genes in these two strains with positive DBA binding and negative Pce activity revealed one SNP in licD1 and four SNPs in licD2, resulting in a single amino acid difference each for LicD1 and LicD2, compared with R36A and D39. CONCLUSION: DBA can bind to the terminal α-GalNAc-(1→3)β-GalNAc of pneumococcal TA and LTA, which is created by Pce. DBA binding is independent of capsule type. The unexpected binding of DBA to the two Pce-negative strains suggests that there is a Pce-independent mechanism for generating the target for DBA binding. Since LicD1 and LicD2 are involved in attaching PC to α-GalNAc-(1→3)β-GalNAc, we are now investigating their role in creating DBA targets independent of Pce. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.
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spelling pubmed-68097222019-10-28 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid Zhou, Meng-Lan Frost, Michael R Nahm, Moon H Open Forum Infect Dis Abstracts BACKGROUND: Dolichos biflorus agglutinin (DBA) is a lectin with a binding specificity toward α-linked N-acetylgalactosamine (α-GalNAc). While DBA is known to bind some, but not all, pneumococci, its target molecule has not been identified. Pneumococcus teichoic acid (TA) and lipoteichoic acid (LTA) have repeating units with α-GalNAc-(1→3)β-GalNAc decorated with phosphorylcholine (PC) at the O-6 positions. Two PC transferases, LicD1 and LicD2, mediate the attachment of PC to GalNAc residues while phosphorylcholine esterase (Pce) removes PCs attached to the terminal GalNAcs. We examined if DBA binds to the terminal α-GalNAc-(1→3)β-GalNAc created by Pce. METHODS: Fifteen pneumococcus strains expressing 14 different serotypes, including one non-encapsulated strain (R36A), were studied with flow cytometry (FC) and confocal fluorescence microscopy (CFM) for DBA binding. Pce enzyme activity was detected with a colorimetric assay using p-nitrophenyl-phosphorylcholine as the substrate. Mutant strains with pce knocked-out were constructed in R36A and D39 by replacing pce with Janus cassette. Both licD genes were sequenced for some of the strains. RESULTS: Ten of the 15 strains had Pce activity and all of them bound DBA (Table 1). When the pce gene was inactivated in two normally Pce-positive strains (R36A(△pce) and D39(△pce)), the strains did not show DBA binding by CFM (Figure 1). Thus, expression of Pce appears to be sufficient for expressing the DBA antigen. Of the five strains that had no Pce activity, two bound DBA. Sequencing of the licD genes in these two strains with positive DBA binding and negative Pce activity revealed one SNP in licD1 and four SNPs in licD2, resulting in a single amino acid difference each for LicD1 and LicD2, compared with R36A and D39. CONCLUSION: DBA can bind to the terminal α-GalNAc-(1→3)β-GalNAc of pneumococcal TA and LTA, which is created by Pce. DBA binding is independent of capsule type. The unexpected binding of DBA to the two Pce-negative strains suggests that there is a Pce-independent mechanism for generating the target for DBA binding. Since LicD1 and LicD2 are involved in attaching PC to α-GalNAc-(1→3)β-GalNAc, we are now investigating their role in creating DBA targets independent of Pce. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures. Oxford University Press 2019-10-23 /pmc/articles/PMC6809722/ http://dx.doi.org/10.1093/ofid/ofz360.2275 Text en © The Author(s) 2019. Published by Oxford University Press on behalf of Infectious Diseases Society of America. http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Abstracts
Zhou, Meng-Lan
Frost, Michael R
Nahm, Moon H
2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title_full 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title_fullStr 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title_full_unstemmed 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title_short 2597. Dolichos biflorus Agglutinin Binds to Pneumococcal Teichoic Acid and Lipoteichoic Acid
title_sort 2597. dolichos biflorus agglutinin binds to pneumococcal teichoic acid and lipoteichoic acid
topic Abstracts
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6809722/
http://dx.doi.org/10.1093/ofid/ofz360.2275
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