Title: Characterization of the binding of the globular domains of the complement component C1q to phosphatidylserine
Authors: Alexandra Kapogianni, Gabriela Radulova, Vancho Donev, Pavel Videv, Ginka Cholakova, Stoyan Iliev, Anela Ivanova, Vanya Bogoeva, Ivanka Tsacheva
DOI: 10.1016/j.ijbiomac.2024.139116
Date: 2024-12-23
Working Group: WG2
Grant Period: GP2
Grant Period Goal (number): 4
Covered deliverables from the MoU (number): 252
Countries involved: Bulgaria
Number of female/young/ITC coauthors: 6/4/9
Is the publication open access?: Yes
Is the publication co-lead by a YRI?: No
Abstract: C1q, the key component of the classical pathway of the Complement system, is known for its vast functional
activity including clearance of apoptotic cells. The binding of C1q to apoptotic blebs occurs via an interaction
with the phosphatidylserine externalized on the cell surface. In this study, we characterized the interaction
between C1q and phosphatidylserine, with emphasis on the structure of the phosphatidylserine-binding site
within the globular domains of C1q and the nature of binding of C1q with phosphatidylserine, using both in vitro
and in silico methods. We established that all three globular fragments, forming one C1q globular domain, bound
phosphatidylserine with the leading role of the phosphatidylserine-binding site pertaining to the A chain of the
globular fragment of C1q. We also determined the closest-contact amino acids of C1q participating in the
interaction with phosphatidylserine. An important role is suggested for the glycosylated Asn124 residue in the A
chain of the globular fragment.
