Title

Decreased metallation and activity in subsets of mutant superoxide dismutases associated with familial amyotrophic lateral sclerosis

UMMS Affiliation

Department of Neurology

Date

2-21-2002

Document Type

Article

Subjects

Amino Acid Substitution; Animals; Binding Sites; Cell Line; Cloning, Molecular; Copper; DNA Primers; Humans; Insects; Motor Neuron Disease; Mutagenesis, Site-Directed; *Mutation; Protein Engineering; Protein Structure, Secondary; Recombinant Proteins; Spectrometry, Mass, Electrospray Ionization; Superoxide Dismutase; Variation (Genetics)

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

Over 90 different mutations in the gene encoding copper/zinc superoxide dismutase (SOD1) cause approximately 2% of amyotrophic lateral sclerosis (ALS) cases by an unknown mechanism. We engineered 14 different human ALS-related SOD1 mutants and obtained high yields of biologically metallated proteins from an Sf21 insect cell expression system. Both the wild type and mutant "as isolated" SOD1 variants were deficient in copper and were heterogeneous by native gel electrophoresis. By contrast, although three mutant SOD1s with substitutions near the metal binding sites (H46R, G85R, and D124V) were severely deficient in both copper and zinc ions, zinc deficiency was not a consistent feature shared by the as isolated mutants. Eight mutants (A4V, L38V, G41S, G72S, D76Y, D90A, G93A, and E133 Delta) exhibited normal SOD activity over pH 5.5-10.5, per equivalent of copper, consistent with the presumption that bound copper was in the proper metal-binding site and was fully active. The H48Q variant contained a high copper content yet was 100-fold less active than the wild type enzyme and exhibited a blue shift in the visible absorbance peak of bound Cu(II), indicating rearrangement of the Cu(II) coordination geometry. Further characterization of these as-isolated SOD1 proteins may provide new insights regarding mutant SOD1 enzyme toxicity in ALS.

Rights and Permissions

Citation: J Biol Chem. 2002 May 3;277(18):15923-31. Epub 2002 Feb 19. Link to article on publisher's site

DOI of Published Version

10.1074/jbc.M112087200

Related Resources

Link to Article in PubMed

Journal Title

The Journal of biological chemistry

PubMed ID

11854284