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Local destabilization of the metal-binding region in human copper-zinc superoxide dismutase by remote mutations is a possible determinant for progression of ALS.
Biochemistry 54, 323-333 (2015)
More than 100 distinct mutations in the gene CuZnSOD encoding human copper-zinc superoxide dismutase (CuZnSOD) have been associated with familial amyotrophic lateral sclerosis (fALS), a fatal neuronal disease. Many studies of different mutant proteins have found effects on protein stability, catalytic activity, and metal binding, but without a common pattern. Notably, these studies were often performed under conditions far from physiological. Here, we have used experimental conditions of pH 7 and 37 °C and at an ionic strength of 0.2 M to mimic physiological conditions as close as possible in a sample of pure protein. Thus, by using NMR spectroscopy, we have analyzed amide hydrogen exchange of the fALS-associated I113T CuZnSOD variant in its fully metalated state, both at 25 and 37 °C, where 15N relaxation data, as expected, reveals that CuZnSOD I113T exists as a dimer under these conditions. The local dynamics at 82% of all residues have been analyzed in detail. When compared to the wild-type protein, it was found that I113T CuZnSOD is particularly destabilized locally at the ion binding sites of loop 4, the zinc binding loop, which results in frequent exposure of the aggregation prone outer β-strands I and VI of the β-barrel, possibly enabling fibril or aggregate formation. A similar study (Museth, A. K., et al. (2009) Biochemistry, 48, 8817-8829) of amide hydrogen exchange at pH 7 and 25 °C on the G93A variant also revealed a selective destabilization of the zinc binding loop. Thus, a possible scenario in ALS is that elevated local dynamics at the metal binding region can result in toxic species from formation of new interactions at local β-strands.
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Publication type
Article: Journal article
Document type
Scientific Article
Keywords
Amyotrophic-lateral-sclerosis; Backbone Dynamics; Staphylococcal Nuclease; Recombinant Human; Relaxation Rates; Nmr-spectroscopy; Motor-neurons; Uk Families; Cell-death; Wild-type
Language
english
Publication Year
2015
HGF-reported in Year
2015
ISSN (print) / ISBN
0006-2960
e-ISSN
1520-4995
Journal
Biochemistry
Quellenangaben
Volume: 54,
Issue: 2,
Pages: 323-333
Publisher
American Chemical Society (ACS)
Publishing Place
Washington
Reviewing status
Peer reviewed
Institute(s)
Institute of Structural Biology (STB)
POF-Topic(s)
30203 - Molecular Targets and Therapies
Research field(s)
Enabling and Novel Technologies
PSP Element(s)
G-503000-001
WOS ID
WOS:000348333300022
Scopus ID
84922448304
Erfassungsdatum
2015-02-20