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EGFP insertional mutagenesis reveals multiple FXR2P fibrillar states with differing ribosome association in neurons

RNA-binding proteins (RBPs) function in higher-order assemblages such as RNA granules to regulate RNA localization and translation. The Fragile X homolog FXR2P is an RBP essential for formation of neuronal Fragile X granules that associate with axonal mRNA and ribosomes in the intact brain. However,...

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Detalles Bibliográficos
Autores principales: Stackpole, Emily E., Akins, Michael R., Ivshina, Maria, Murthy, Anastasia C., Fawzi, Nicolas L., Fallon, Justin R.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Company of Biologists Ltd 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6737979/
https://www.ncbi.nlm.nih.gov/pubmed/31434643
http://dx.doi.org/10.1242/bio.046383
Descripción
Sumario:RNA-binding proteins (RBPs) function in higher-order assemblages such as RNA granules to regulate RNA localization and translation. The Fragile X homolog FXR2P is an RBP essential for formation of neuronal Fragile X granules that associate with axonal mRNA and ribosomes in the intact brain. However, the FXR2P domains important for assemblage formation in a cellular system are unknown. Here we used an EGFP insertional mutagenesis approach to probe for FXR2P intrinsic features that influence its structural states. We tested 18 different in-frame FXR2P(EGFP) fusions in neurons and found that the majority did not impact assemblage formation. However, EGFP insertion within a 23 amino acid region of the low complexity (LC) domain induced FXR2P(EGFP) assembly into two distinct fibril states that were observed in isolation or in highly-ordered bundles. FXR2P(EGFP) fibrils exhibited different developmental timelines, ultrastructures and ribosome associations. Formation of both fibril types was dependent on an intact RNA-binding domain. These results suggest that restricted regions of the LC domain, together with the RNA-binding domain, may be important for FXR2P structural state organization in neurons.