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Elife. 2016 Jan 8;5. pii: e11297. doi: 10.7554/eLife.11297.

Structural basis of nucleic-acid recognition and double-strand unwinding by the essential neuronal protein Pur-alpha.

Author information

1
Institute of Structural Biology, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany.
2
Department of Human Genetics, Emory University, Atlanta, United States.
3
Center for Integrated Protein Science Munich, Department of Chemistry, Technische Universität München, Munich, Germany.
4
Institute of Molecular Biology & Biochemistry, Center of Molecular Medicine, Medical University of Graz, Graz, Austria.
5
Omics Center Graz, BioTechMed Graz, Graz, Austria.
6
Department Cell Biology, Biomedical Center of the Ludwig-Maximilians-University München, Planegg-Martinsried, Germany.

Abstract

The neuronal DNA-/RNA-binding protein Pur-alpha is a transcription regulator and core factor for mRNA localization. Pur-alpha-deficient mice die after birth with pleiotropic neuronal defects. Here, we report the crystal structure of the DNA-/RNA-binding domain of Pur-alpha in complex with ssDNA. It reveals base-specific recognition and offers a molecular explanation for the effect of point mutations in the 5q31.3 microdeletion syndrome. Consistent with the crystal structure, biochemical and NMR data indicate that Pur-alpha binds DNA and RNA in the same way, suggesting binding modes for tri- and hexanucleotide-repeat RNAs in two neurodegenerative RNAopathies. Additionally, structure-based in vitro experiments resolved the molecular mechanism of Pur-alpha's unwindase activity. Complementing in vivo analyses in Drosophila demonstrated the importance of a highly conserved phenylalanine for Pur-alpha's unwinding and neuroprotective function. By uncovering the molecular mechanisms of nucleic-acid binding, this study contributes to understanding the cellular role of Pur-alpha and its implications in neurodegenerative diseases.

KEYWORDS:

5q31.3 microdeletion syndrome; <i>d. melanogaster</i>; <i>e. coli</i>; ALS; DNA unwinding; DNA-/RNA-protein interaction; FXTAS; X-ray crystallography; biochemistry; biophysics; structural biology

PMID:
26744780
PMCID:
PMC4764581
DOI:
10.7554/eLife.11297
[Indexed for MEDLINE]
Free PMC Article

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