7QIV

Structure of human C3b in complex with the EWE nanobody

Summary for 7QIV

• Entry DOI: 10.2210/pdb7qiv/pdb
• Related: 6EHG 6RU5
• Descriptor: Complement C3 beta chain, Complement C3b alpha' chain, Nanobody EWE, ... (4 entities in total)
• Functional Keywords: complement, alternative pathway, antibody, nanobody, protein engineering, immune system
• Biological source: Lama glama; More
• Total number of polymer chains: 3
• Total formula weight: 190700.22

Authors

Pedersen, H.,Andersen, G.R. (deposition date: 2021-12-16, release date: 2022-02-16, Last modification date: 2024-10-16)

Primary citation

Pedersen, H.,Jensen, R.K.,Hansen, A.G.,Petersen, S.V.,Thiel, S.,Laursen, N.S.,Andersen, G.R.
Structure-Guided Engineering of a Complement Component C3-Binding Nanobody Improves Specificity and Adds Cofactor Activity.
Front Immunol, 13:872536-872536, 2022

PubMed Abstract: The complement system is a part of the innate immune system, where it labels intruding pathogens as well as dying host cells for clearance. If complement regulation is compromised, the system may contribute to pathogenesis. The proteolytic fragment C3b of complement component C3, is the pivot point of the complement system and provides a scaffold for the assembly of the alternative pathway C3 convertase that greatly amplifies the initial complement activation. This makes C3b an attractive therapeutic target. We previously described a nanobody, hC3Nb1 binding to C3 and its degradation products. Here we show, that extending the N-terminus of hC3Nb1 by a Glu-Trp-Glu motif renders the resulting EWE-hC3Nb1 (EWE) nanobody specific for C3 degradation products. By fusing EWE to N-terminal CCP domains from complement Factor H (FH), we generated the fusion proteins EWEnH and EWEµH. In contrast to EWE, these fusion proteins supported Factor I (FI)-mediated cleavage of human and rat C3b. The EWE, EWEµH, and EWEnH proteins bound C3b and iC3b with low nanomolar dissociation constants and exerted strong inhibition of alternative pathway-mediated deposition of complement. Interestingly, EWEnH remained soluble above 20 mg/mL. Combined with the observed reactivity with both human and rat C3b as well as the ability to support FI-mediated cleavage of C3b, this features EWEnH as a promising candidate for studies in rodent models of complement driven pathogenesis.

PubMed: 35935935
DOI: 10.3389/fimmu.2022.872536

Experimental method

X-RAY DIFFRACTION (2.8 Å)