7TE3

Crystal Structure of a Double Loop Deletion Mutant in gC1qR/C1qBP/HABP-1

7TE3 の概要

• エントリーDOI: 10.2210/pdb7te3/pdb
• 分子名称: Complement component 1 Q subcomponent-binding protein, mitochondrial (2 entities in total)
• 機能のキーワード: complement, c1q-binding protein, coagulation, immune system
• 由来する生物種: Homo sapiens (human)
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 20030.24

構造登録者

Geisbrecht, B.V. (登録日: 2022-01-04, 公開日: 2022-06-01, 最終更新日: 2023-10-25)

主引用文献

Zhang, Y.,Vontz, A.J.,Kallenberger, E.M.,Xu, X.,Ploscariu, N.T.,Ramyar, K.X.,Garcia, B.L.,Ghebrehiwet, B.,Geisbrecht, B.V.
gC1qR/C1qBP/HABP-1: Structural Analysis of the Trimeric Core Region, Interactions With a Novel Panel of Monoclonal Antibodies, and Their Influence on Binding to FXII.
Front Immunol, 13:887742-887742, 2022

PubMed Abstract: The protein gC1qR/C1qBP/HABP-1 plays an essential role in mitochondrial biogenesis, but becomes localized at the cellular surface in numerous pathophysiological states. When this occurs on endothelial cells, surface-exposed gC1qR activates the classical pathway of complement. It also promotes assembly of a multi-protein complex comprised of coagulation factor XII (FXII), pre-kallikrein (PK), and high-molecular weight kininogen (HMWK) that activates the contact system and the kinin-generating system. Since surface-exposed gC1qR triggers intravascular inflammatory pathways, there is interest in identifying molecules that block gC1qR function. Here we further that objective by reporting the outcome of a structure/function investigation of gC1qR, its interactions with FXII, and the impact of a panel of monoclonal anti-gC1qR antibodies on FXII binding to gC1qR. Although deletion mutants have been used extensively to assess gC1qR function, none of these proteins have been characterized structurally. To that end, we determined a 2.2 Å resolution crystal structure of a gC1qR mutant lacking both of its acidic loops, but which retained nanomolar-affinity binding to FXII and FXIIa. This structure revealed that the trimeric gC1qR assembly was maintained despite loss of roughly thirty residues. Characterization of a novel panel of anti-gC1qR monoclonal antibodies identified several with biochemical properties distinct from previously described antibodies, as well as one which bound to the first acidic loop of gC1qR. Intriguingly, we found that each of these antibodies could partly inhibit binding of FXII and FXIIa to gC1qR. Based on these results and previously published studies, we offer new perspectives for developing gC1qR inhibitors.

PubMed: 35865516
DOI: 10.3389/fimmu.2022.887742

実験手法

X-RAY DIFFRACTION (2.2 Å)