Single mutation induces a metal-dependent subunit association in dimeric Cu,Zn superoxide dismutase.
Tryptophan 83, a residue strongly involved in the intersubunit interaction of the Cu,Zn superoxide dismutases from Photobacterium leiognathi, has been selectively mutated to phenylalanine or tyrosine. The recombinant mutant enzymes expressed in Escherichia coli were purified in two well distinct and stable forms, one dimeric and fully active and the other monomeric and devoid of metals. In agreement, in vitro experiments indicate that the removal and addition of zinc in the mutant enzymes induces monomerization and dimerization, respectively, while does not perturb the dimeric association of the native protein. This is the first unambiguous experimental proof of a direct communication between the intersubunit interface and the metal active site.
D'Orazio
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Department of Biology, University of Rome Tor Vergata, Italy.
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D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D008670:Metals / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D010776:Photobacterium / Q000201:enzymology / Q000235:genetics; D017354:Point Mutation; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D013482:Superoxide Dismutase / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification
D017931:DNA Primers; D008670:Metals; D011994:Recombinant Proteins; D013482:Superoxide Dismutase