7SJP

anti-HtrA1 Fab15H6.v4 bound to HtrA1-LoopA peptide

Summary for 7SJP

• Entry DOI: 10.2210/pdb7sjp/pdb
• Related: 7SJM
• Descriptor: HtrA1-LoopA peptide, Heavy Chain, Light Chain, ... (6 entities in total)
• Functional Keywords: fab htra 1 peptide complex, immune system
• Biological source: Homo sapiens; More
• Total number of polymer chains: 3
• Total formula weight: 49631.85

Authors

Ultsch, M.H.,Gerhardy, S. (deposition date: 2021-10-18, release date: 2022-09-07, Last modification date: 2024-11-06)

Primary citation

Gerhardy, S.,Ultsch, M.,Tang, W.,Green, E.,Holden, J.K.,Li, W.,Estevez, A.,Arthur, C.,Tom, I.,Rohou, A.,Kirchhofer, D.
Allosteric inhibition of HTRA1 activity by a conformational lock mechanism to treat age-related macular degeneration.
Nat Commun, 13:5222-5222, 2022

PubMed Abstract: The trimeric serine protease HTRA1 is a genetic risk factor associated with geographic atrophy (GA), a currently untreatable form of age-related macular degeneration. Here, we describe the allosteric inhibition mechanism of HTRA1 by a clinical Fab fragment, currently being evaluated for GA treatment. Using cryo-EM, X-ray crystallography and biochemical assays we identify the exposed LoopA of HTRA1 as the sole Fab epitope, which is approximately 30 Å away from the active site. The cryo-EM structure of the HTRA1:Fab complex in combination with molecular dynamics simulations revealed that Fab binding to LoopA locks HTRA1 in a non-competent conformational state, incapable of supporting catalysis. Moreover, grafting the HTRA1-LoopA epitope onto HTRA2 and HTRA3 transferred the allosteric inhibition mechanism. This suggests a conserved conformational lock mechanism across the HTRA family and a critical role of LoopA for catalysis, which was supported by the reduced activity of HTRA1-3 upon LoopA deletion or perturbation. This study reveals the long-range inhibition mechanism of the clinical Fab and identifies an essential function of the exposed LoopA for activity of HTRA family proteases.

PubMed: 36064790
DOI: 10.1038/s41467-022-32760-9

Experimental method

X-RAY DIFFRACTION (2.1 Å)