Program in Molecular Medicine
Amino Acids, Peptides, and Proteins | Biochemistry, Biophysics, and Structural Biology | Congenital, Hereditary, and Neonatal Diseases and Abnormalities | Neuroscience and Neurobiology | Nucleic Acids, Nucleotides, and Nucleosides
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.
Fragile X syndrome, Local protein synthesis, Low complexity, RNA granule, RNA-binding protein
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© 2019. Published by The Company of Biologists Ltd. 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 that the original work is properly attributed.
DOI of Published Version
Biol Open. 2019 Aug 21;8(8). pii: 8/8/bio046383. doi: 10.1242/bio.046383. Link to article on publisher's site
Stackpole, Emily E.; Akins, Michael R.; Ivshina, Mariya; Murthy, Anastasia C.; Fawzi, Nicolas L.; and Fallon, Justin R., "EGFP insertional mutagenesis reveals multiple FXR2P fibrillar states with differing ribosome association in neurons" (2019). Open Access Articles. 3938.
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