Structural transitions of complement component C3 and its activation products.

Noritaka Nishida; Thomas Walz; Timothy A Springer

doi:10.1073/pnas.0609791104

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Structural transitions of complement component C3 and its activation products.

Noritaka Nishida·Thomas Walz·Timothy A Springer

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Abstract

Complement sensitizes pathogens for phagocytosis and lysis. We use electron microscopy to examine the structural transitions in the activation of the pivotal protein in the complement pathway, C3. In the cleavage product C3b, the position of the thioester domain moves approximately 100 Angstrom, which becomes covalently coupled to antigenic surfaces. In the iC3b fragment, cleavage in an intervening domain creates a long flexible linker between the thioester domain and the macroglobulin domain ring of C3. Studies on two products of nucleophile addition to C3 reveal a structural intermediate in activation, and a final product, in which the anaphylatoxin domain has undergone a remarkable movement through the macroglobulin ring.

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Chromatography, Gel Complement C3 Crystallography, X-Ray Humans Microscopy, Electron Models, Molecular Protein Binding Protein Structure, Quaternary Journal Article Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't

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Noritaka Nishida, Thomas Walz, Timothy A Springer. 2006-12-15. Structural transitions of complement component C3 and its activation products.. https://doi.org/10.1073/pnas.0609791104

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