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Electrostatic modeling predicts the activities of orthopoxvirus complement control proteins
Georgia Sfyroera1, Madan Katragadda, Dimitrios Morikis
1Department of Pathology and Laboratory Medicine,University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|February 9, 2005
Summary
Altering vaccinia virus proteins to mimic variola virus proteins enhances complement control. This research clarifies how electrostatic potential influences protein function and aids in designing new complement inhibitors.
Area of Science:
- Immunology
- Virology
- Structural Biology
Background:
- Complement activation is vital for host defense against pathogens.
- Orthopoxviruses encode complement control proteins (CCPs) to evade immune responses.
- Vaccinia virus (VACV) and variola virus (VARV) CCPs exhibit significant differences in complement regulatory activity.
Purpose of the Study:
- To investigate the role of electrostatic potential in predicting the functional activity of VACV and VARV CCPs.
- To identify critical residues influencing complement regulatory function through protein mutagenesis.
- To explore the implications for designing novel complement inhibitors.
Main Methods:
- Comparative analysis of VACV and VARV CCP sequences.
- Electrostatic potential modeling of viral CCPs.
- Site-directed mutagenesis of VACV CCP.
- Functional assays measuring C3b binding, alternative pathway inhibition, and cofactor activity.
Main Results:
- Electrostatic modeling accurately predicted increased complement regulatory activity upon altering VACV CCP.
- Mutagenesis confirmed that modifying electrostatic potential enhances VACV CCP function, including C3b binding and alternative pathway inhibition.
- VARV CCP, despite enhanced activity, did not cleave the C3b alpha' chain at specific residues (954-955).
Conclusions:
- Electrostatic potential is a key determinant of orthopoxvirus CCP function.
- Specific residues and their electrostatic properties critically influence complement regulation.
- Findings inform the rational design of therapeutic complement inhibitors for immune modulation.