Mechanism of APTX nicked DNA sensing and pleiotropic inactivation in neurodegenerative disease

Autor: Emma E. Fairweather, R.S. Williams, Matthew J. Schellenberg, Ian D. Waddell, J Little, Percy P. Tumbale, Mandy Watson, Geoffrey A. Mueller, Robert E. London, Juno M. Krahn
Rok vydání: 2017
Předmět:
0301 basic medicine
Models
Molecular
Magnetic Resonance Spectroscopy
DNA repair
Protein Conformation
Ribonucleotide excision repair
DNA Mutational Analysis
aptX
DNA Ligases
Ataxia Oculomotor Apraxia 1
X‐ray crystallography
medicine.disease_cause
Crystallography
X-Ray
APTX
General Biochemistry
Genetics and Molecular Biology
Article
03 medical and health sciences
chemistry.chemical_compound
Structural Biology
Catalytic Domain
medicine
Humans
Molecular Biology of Disease
DNA Breaks
Single-Stranded
Molecular Biology
chemistry.chemical_classification
Mutation
DNA ligase
General Immunology and Microbiology
biology
Protein Stability
General Neuroscience
missense mutation
Active site
Nuclear Proteins
DNA Replication
Repair & Recombination
Neurodegenerative Diseases
DNA
Articles
Cell biology
DNA-Binding Proteins
030104 developmental biology
chemistry
biology.protein
RNA
Protein Binding
Zdroj: The EMBO Journal
ISSN: 1460-2075
Popis: The failure of DNA ligases to complete their catalytic reactions generates cytotoxic adenylated DNA strand breaks. The APTX RNA‐DNA deadenylase protects genome integrity and corrects abortive DNA ligation arising during ribonucleotide excision repair and base excision DNA repair, and APTX human mutations cause the neurodegenerative disorder ataxia with oculomotor ataxia 1 (AOA1). How APTX senses cognate DNA nicks and is inactivated in AOA1 remains incompletely defined. Here, we report X‐ray structures of APTX engaging nicked RNA‐DNA substrates that provide direct evidence for a wedge‐pivot‐cut strategy for 5′‐AMP resolution shared with the alternate 5′‐AMP processing enzymes POLβ and FEN1. Our results uncover a DNA‐induced fit mechanism regulating APTX active site loop conformations and assembly of a catalytically competent active center. Further, based on comprehensive biochemical, X‐ray and solution NMR results, we define a complex hierarchy for the differential impacts of the AOA1 mutational spectrum on APTX structure and activity. Sixteen AOA1 variants impact APTX protein stability, one mutation directly alters deadenylation reaction chemistry, and a dominant AOA1 variant unexpectedly allosterically modulates APTX active site conformations.
Databáze: OpenAIRE
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