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Updated: Jul 13, 2026
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Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques
Published on: July 5, 2018
High-resolution structures of bacterially expressed soluble human CD59.
Kirstin J Leath1, Steven Johnson, Pietro Roversi
1Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, England.
Summary
Researchers determined the high-resolution crystal structures of soluble human CD59, a complement inhibitor. One structure revealed a bound molecule in the C8/C9-binding site, influencing protein conformation.
Area of Science:
- Biochemistry
- Structural Biology
- Immunology
Background:
- CD59 is a crucial host cell protectant against complement-mediated lysis.
- It functions by inhibiting the terminal complement pathway and preventing Membrane Attack Complex (MAC) formation.
Purpose of the Study:
- To elucidate the high-resolution structure of soluble human CD59.
- To investigate the structural basis of CD59's interaction with complement components.
Main Methods:
- Bacterial expression and purification of nonglycosylated recombinant soluble human CD59.
- Crystallization of CD59 under three different conditions.
- High-resolution (1.15-1.8 Å) X-ray crystallography and structure determination.
Main Results:
- Three distinct crystal forms of soluble human CD59 were obtained and characterized.
- High-resolution crystal structures revealed detailed molecular architecture.
- An unidentified small molecule was observed bound to the predicted C8/C9-binding site in one structure.
- Ligand binding correlated with alternative conformations of key C8/C9-binding residues.
Conclusions:
- The determined CD59 structures provide atomic-level insights into its function.
- The presence of a bound ligand in the C8/C9-binding site suggests a regulatory mechanism.
- Ligand-induced conformational changes may modulate CD59's inhibitory activity on complement.
