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The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls
BACKGROUND: Acanthamoeba castellanii, which causes keratitis and blindness in under-resourced countries, is an emerging pathogen worldwide, because of its association with contact lens use. The wall makes cysts resistant to sterilizing reagents in lens solutions and to antibiotics applied to the eye...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6541295/ https://www.ncbi.nlm.nih.gov/pubmed/31095564 http://dx.doi.org/10.1371/journal.pntd.0007352 |
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author | Magistrado-Coxen, Pamela Aqeel, Yousuf Lopez, Angelo Haserick, John R. Urbanowicz, Breeanna R. Costello, Catherine E. Samuelson, John |
author_facet | Magistrado-Coxen, Pamela Aqeel, Yousuf Lopez, Angelo Haserick, John R. Urbanowicz, Breeanna R. Costello, Catherine E. Samuelson, John |
author_sort | Magistrado-Coxen, Pamela |
collection | PubMed |
description | BACKGROUND: Acanthamoeba castellanii, which causes keratitis and blindness in under-resourced countries, is an emerging pathogen worldwide, because of its association with contact lens use. The wall makes cysts resistant to sterilizing reagents in lens solutions and to antibiotics applied to the eye. METHODOLOGY/PRINCIPAL FINDINGS: Transmission electron microscopy and structured illumination microscopy (SIM) showed purified cyst walls of A. castellanii retained an outer ectocyst layer, an inner endocyst layer, and conical ostioles that connect them. Mass spectrometry showed candidate cyst wall proteins were dominated by three families of lectins (named here Jonah, Luke, and Leo), which bound well to cellulose and less well to chitin. An abundant Jonah lectin, which has one choice-of-anchor A (CAA) domain, was made early during encystation and localized to the ectocyst layer of cyst walls. An abundant Luke lectin, which has two carbohydrate-binding modules (CBM49), outlined small, flat ostioles in a single-layered primordial wall and localized to the endocyst layer and ostioles of mature walls. An abundant Leo lectin, which has two unique domains with eight Cys residues each (8-Cys), localized to the endocyst layer and ostioles. The Jonah lectin and glycopolymers, to which it binds, were accessible in the ectocyst layer. In contrast, Luke and Leo lectins and the glycopolymers, to which they bind, were mostly inaccessible in the endocyst layer and ostioles. CONCLUSIONS/SIGNIFICANCE: The most abundant A. castellanii cyst wall proteins are three sets of lectins, which have carbohydrate-binding modules that are conserved (CBM49s of Luke), newly characterized (CAA of Jonah), or unique to Acanthamoebae (8-Cys of Leo). Cyst wall formation is a tightly choreographed event, in which lectins and glycopolymers combine to form a mature wall with a protected endocyst layer. Because of its accessibility in the ectocyst layer, an abundant Jonah lectin is an excellent diagnostic target. |
format | Online Article Text |
id | pubmed-6541295 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-65412952019-06-05 The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls Magistrado-Coxen, Pamela Aqeel, Yousuf Lopez, Angelo Haserick, John R. Urbanowicz, Breeanna R. Costello, Catherine E. Samuelson, John PLoS Negl Trop Dis Research Article BACKGROUND: Acanthamoeba castellanii, which causes keratitis and blindness in under-resourced countries, is an emerging pathogen worldwide, because of its association with contact lens use. The wall makes cysts resistant to sterilizing reagents in lens solutions and to antibiotics applied to the eye. METHODOLOGY/PRINCIPAL FINDINGS: Transmission electron microscopy and structured illumination microscopy (SIM) showed purified cyst walls of A. castellanii retained an outer ectocyst layer, an inner endocyst layer, and conical ostioles that connect them. Mass spectrometry showed candidate cyst wall proteins were dominated by three families of lectins (named here Jonah, Luke, and Leo), which bound well to cellulose and less well to chitin. An abundant Jonah lectin, which has one choice-of-anchor A (CAA) domain, was made early during encystation and localized to the ectocyst layer of cyst walls. An abundant Luke lectin, which has two carbohydrate-binding modules (CBM49), outlined small, flat ostioles in a single-layered primordial wall and localized to the endocyst layer and ostioles of mature walls. An abundant Leo lectin, which has two unique domains with eight Cys residues each (8-Cys), localized to the endocyst layer and ostioles. The Jonah lectin and glycopolymers, to which it binds, were accessible in the ectocyst layer. In contrast, Luke and Leo lectins and the glycopolymers, to which they bind, were mostly inaccessible in the endocyst layer and ostioles. CONCLUSIONS/SIGNIFICANCE: The most abundant A. castellanii cyst wall proteins are three sets of lectins, which have carbohydrate-binding modules that are conserved (CBM49s of Luke), newly characterized (CAA of Jonah), or unique to Acanthamoebae (8-Cys of Leo). Cyst wall formation is a tightly choreographed event, in which lectins and glycopolymers combine to form a mature wall with a protected endocyst layer. Because of its accessibility in the ectocyst layer, an abundant Jonah lectin is an excellent diagnostic target. Public Library of Science 2019-05-16 /pmc/articles/PMC6541295/ /pubmed/31095564 http://dx.doi.org/10.1371/journal.pntd.0007352 Text en © 2019 Magistrado-Coxen et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Magistrado-Coxen, Pamela Aqeel, Yousuf Lopez, Angelo Haserick, John R. Urbanowicz, Breeanna R. Costello, Catherine E. Samuelson, John The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title | The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title_full | The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title_fullStr | The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title_full_unstemmed | The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title_short | The most abundant cyst wall proteins of Acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
title_sort | most abundant cyst wall proteins of acanthamoeba castellanii are lectins that bind cellulose and localize to distinct structures in developing and mature cyst walls |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6541295/ https://www.ncbi.nlm.nih.gov/pubmed/31095564 http://dx.doi.org/10.1371/journal.pntd.0007352 |
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