The structure of human mitochondrial manganese superoxide dismutase reveals a novel tetrameric interface of two 4-helix bundles.
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Borgstahl GE, Parge HE, Hickey MJ, Beyer WF Jr, Hallewell RA, Tainer JA
The structure of human mitochondrial manganese superoxide dismutase reveals a novel tetrameric interface of two 4-helix bundles.
Cell. 1992 Oct 2;71(1):107-18.
- PubMed ID
- 1394426 [ View in PubMed]
- Abstract
The 2.2 A resolution crystal structure of recombinant human manganese superoxide dismutase, a homotetrameric enzyme that protects mitochondria against oxygen-mediated free radical damage, has been determined. Within each subunit, both the N-terminal helical hairpin and C-terminal alpha/beta domains contribute ligands to the catalytic manganese site. Two identical 4-helix bundles, symmetrically assembled from the N-terminal helical hairpins, form novel tetrameric interfaces that stabilize the active sites. Structurally altered polymorphic variants with reduced activity, such as tetrameric interface mutant Ile-58 to Thr, may produce not only an early selective advantage, through enhanced cytotoxicity of tumor necrosis factor for virus-infected cells, but also detrimental effects from increased mitochondrial oxidative damage, contributing to degenerative conditions, including diabetes, aging, and Parkinson's and Alzheimer's diseases.