9RXI

Schistosoma mansoni Cathepsin D1 bound to Nb10C9

Summary for 9RXI

• Entry DOI: 10.2210/pdb9rxi/pdb
• Descriptor: Cathepsin D (A01 family), Nb_10C9, CALCIUM ION, ... (5 entities in total)
• Functional Keywords: aspartyl protease, schistosoma, cathepsin, single-domain antibody, vhh, hydrolase
• Biological source: Schistosoma mansoni; More
• Total number of polymer chains: 6
• Total formula weight: 201325.05

Authors

Parker, K.,Clarke, J.D.,Owens, R.J. (deposition date: 2025-07-11, release date: 2026-01-28, Last modification date: 2026-02-18)

Primary citation

Parker, K.L.,Clarke, J.D.,Liu, X.,Gomes, B.F.,Eyssen, L.E.A.,Furnham, N.,Paes Silva-Jr, F.,Owens, R.J.
Crystal structure of Schistosoma mansoni cathepsin D1 in complex with a nanobody reveals the conformation of the propeptide-bound state.
Acta Crystallogr D Struct Biol, 82:140-150, 2026

PubMed Abstract: Schistosoma mansoni cathepsin D1 (SmCD1) has been shown to be an essential enzyme for helminth metabolism due to its role in haemoglobin degradation: a key amino-acid source for the developing parasite. Therefore, the enzyme is a potential target for the development of antischistosomal inhibitors. SmCD1 has significant sequence identity to cathepsin D-like proteases found in other schistosome species and homology to mammalian aspartic proteases. Here, we report the first crystal structures of a helminth cathepsin D, SmCD1, and have identified a single-domain antibody (nanobody) that specifically binds to SmCD1 with nanomolar affinity but does not recognize human cathepsin D. We have mapped the epitope of the nanobody by determining the crystal structure of the enzyme-nanobody complex, revealing the conformation of SmCD1 in the propeptide-bound state.

PubMed: 41603320
DOI: 10.1107/S2059798326000422

Experimental method

X-RAY DIFFRACTION (2.59 Å)