Interaction between separated consecutive complement control modules of human C1r: implications for dimerization of
András Láng1, Balázs Major, Katalin Szilágyi
1Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary.
FEBS Letters
|October 26, 2010
Summary
Complement control protein (CCP) modules in human C1r serine protease interact differently in solution than when linked. This study provides evidence for a distinct intermolecular interface, suggesting a switch between functional states.
Area of Science:
- Biochemistry
- Immunology
- Structural Biology
Background:
- Complement control protein (CCP) modules mediate protein:protein interactions in vertebrate immune responses.
- The human C1r serine protease (SP) plays a key role in the classical complement pathway.
Purpose of the Study:
- To provide experimental evidence for intermolecular interactions between the CCP1 and CCP2 modules of human C1r.
- To characterize the interaction interface and its potential role in regulating C1r function.
Main Methods:
- Nuclear Magnetic Resonance (NMR) chemical shift perturbation mapping was employed to identify interaction sites.
- Structural models were built based on the NMR data to visualize the interaction interface.
Main Results:
- Experimental evidence confirms intermolecular interactions between the CCP1 and CCP2 modules of human C1r.
- The identified interaction interface is distinct from that of the covalently linked CCP1-CCP2 pair.
- Structural models suggest an extended interaction interface and a potential structural rearrangement.
Conclusions:
- The distinct intermolecular interaction interface of C1r CCP modules suggests a novel mechanism for regulating its function.
- These findings indicate that C1r may exist in different functional states, potentially regulated by structural rearrangements upon interaction.
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