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U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors

U2 snRNP is an essential component of the spliceosome. It is responsible for branch point recognition in the spliceosome A-complex via base-pairing of U2 snRNA with an intron to form the branch helix. Small molecule inhibitors target the SF3B component of the U2 snRNP and interfere with A-complex fo...

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Autores principales: Urabe, Veronica K., Stevers, Meredith, Ghosh, Arun K., Jurica, Melissa S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8516221/
https://www.ncbi.nlm.nih.gov/pubmed/34648557
http://dx.doi.org/10.1371/journal.pone.0258551
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author Urabe, Veronica K.
Stevers, Meredith
Ghosh, Arun K.
Jurica, Melissa S.
author_facet Urabe, Veronica K.
Stevers, Meredith
Ghosh, Arun K.
Jurica, Melissa S.
author_sort Urabe, Veronica K.
collection PubMed
description U2 snRNP is an essential component of the spliceosome. It is responsible for branch point recognition in the spliceosome A-complex via base-pairing of U2 snRNA with an intron to form the branch helix. Small molecule inhibitors target the SF3B component of the U2 snRNP and interfere with A-complex formation during spliceosome assembly. We previously found that the first SF3B inhibited-complex is less stable than A-complex and hypothesized that SF3B inhibitors interfere with U2 snRNA secondary structure changes required to form the branch helix. Using RNA chemical modifiers, we probed U2 snRNA structure in A-complex and SF3B inhibited splicing complexes. The reactivity pattern for U2 snRNA in the SF3B inhibited-complex is indistinguishable from that of A-complex, suggesting that they have the same secondary structure conformation, including the branch helix. This observation suggests SF3B inhibited-complex instability does not stem from an alternate RNA conformation and instead points to the inhibitors interfering with protein component interactions that normally stabilize U2 snRNP’s association with an intron. In addition, we probed U2 snRNA in the free U2 snRNP in the presence of SF3B inhibitor and again saw no differences. However, increased protection of nucleotides upstream of Stem I in the absence of SF3A and SF3B proteins suggests a change of secondary structure at the very 5′ end of U2 snRNA. Chemical probing of synthetic U2 snRNA in the absence of proteins results in similar protections and predicts a previously uncharacterized extension of Stem I. Because this stem must be disrupted for SF3A and SF3B proteins to stably join the snRNP, the structure has the potential to influence snRNP assembly and recycling after spliceosome disassembly.
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spelling pubmed-85162212021-10-15 U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors Urabe, Veronica K. Stevers, Meredith Ghosh, Arun K. Jurica, Melissa S. PLoS One Research Article U2 snRNP is an essential component of the spliceosome. It is responsible for branch point recognition in the spliceosome A-complex via base-pairing of U2 snRNA with an intron to form the branch helix. Small molecule inhibitors target the SF3B component of the U2 snRNP and interfere with A-complex formation during spliceosome assembly. We previously found that the first SF3B inhibited-complex is less stable than A-complex and hypothesized that SF3B inhibitors interfere with U2 snRNA secondary structure changes required to form the branch helix. Using RNA chemical modifiers, we probed U2 snRNA structure in A-complex and SF3B inhibited splicing complexes. The reactivity pattern for U2 snRNA in the SF3B inhibited-complex is indistinguishable from that of A-complex, suggesting that they have the same secondary structure conformation, including the branch helix. This observation suggests SF3B inhibited-complex instability does not stem from an alternate RNA conformation and instead points to the inhibitors interfering with protein component interactions that normally stabilize U2 snRNP’s association with an intron. In addition, we probed U2 snRNA in the free U2 snRNP in the presence of SF3B inhibitor and again saw no differences. However, increased protection of nucleotides upstream of Stem I in the absence of SF3A and SF3B proteins suggests a change of secondary structure at the very 5′ end of U2 snRNA. Chemical probing of synthetic U2 snRNA in the absence of proteins results in similar protections and predicts a previously uncharacterized extension of Stem I. Because this stem must be disrupted for SF3A and SF3B proteins to stably join the snRNP, the structure has the potential to influence snRNP assembly and recycling after spliceosome disassembly. Public Library of Science 2021-10-14 /pmc/articles/PMC8516221/ /pubmed/34648557 http://dx.doi.org/10.1371/journal.pone.0258551 Text en © 2021 Urabe et al https://creativecommons.org/licenses/by/4.0/This is an open access article distributed under the terms of the Creative Commons Attribution License (https://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
Urabe, Veronica K.
Stevers, Meredith
Ghosh, Arun K.
Jurica, Melissa S.
U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title_full U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title_fullStr U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title_full_unstemmed U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title_short U2 snRNA structure is influenced by SF3A and SF3B proteins but not by SF3B inhibitors
title_sort u2 snrna structure is influenced by sf3a and sf3b proteins but not by sf3b inhibitors
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8516221/
https://www.ncbi.nlm.nih.gov/pubmed/34648557
http://dx.doi.org/10.1371/journal.pone.0258551
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