Consejo Nacional de Ciencia y Tecnologia (CONACYT)
604718
Mexico
Citation
Journal: J Immunol / Year: 2022 Title: Multifaceted Activities of Seven Nanobodies against Complement C4b. Authors: Karla I De la O Becerra / Wout Oosterheert / Ramon M van den Bos / Katerina T Xenaki / Joseph H Lorent / Maartje Ruyken / Arie Schouten / Suzan H M Rooijakkers / Paul M P van Bergen En Henegouwen / Piet Gros / Abstract: Cleavage of the mammalian plasma protein C4 into C4b initiates opsonization, lysis, and clearance of microbes and damaged host cells by the classical and lectin pathways of the complement system. ...Cleavage of the mammalian plasma protein C4 into C4b initiates opsonization, lysis, and clearance of microbes and damaged host cells by the classical and lectin pathways of the complement system. Dysregulated activation of C4 and other initial components of the classical pathway may cause or aggravate pathologies, such as systemic lupus erythematosus, Alzheimer disease, and schizophrenia. Modulating the activity of C4b by small-molecule or protein-based inhibitors may represent a promising therapeutic approach for preventing excessive inflammation and damage to host cells and tissue. Here, we present seven nanobodies, derived from llama () immunization, that bind to human C4b () with high affinities ranging from 3.2 nM to 14 pM. The activity of the nanobodies varies from no to complete inhibition of the classical pathway. The inhibiting nanobodies affect different steps in complement activation, in line with blocking sites for proconvertase formation, C3 substrate binding to the convertase, and regulator-mediated inactivation of C4b. For four nanobodies, we determined single-particle cryo-electron microscopy structures in complex with C4b at 3.4-4 Å resolution. The structures rationalize the observed functional effects of the nanobodies and define their mode of action during complement activation. Thus, we characterized seven anti-C4b nanobodies with diverse effects on the classical pathway of complement activation that may be explored for imaging, diagnostic, or therapeutic applications.
History
Deposition
Nov 27, 2020
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Header (metadata) release
Mar 2, 2022
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Map release
Mar 2, 2022
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Update
May 4, 2022
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Current status
May 4, 2022
Processing site: PDBe / Status: Released
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Structure visualization
Movie
Surface view with section colored by density value
Supramolecule #1: Complement C4b bound to nanobody B5
Supramolecule
Name: Complement C4b bound to nanobody B5 / type: complex / ID: 1 / Parent: 0 / Macromolecule list: #1-#4 Details: The purchased C4b is generated from a mixture of C4A and C4B. C4b is modelled with the sequence of C4A based on pdb 5jtw.
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