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Intracellular Neutralization of Ricin Toxin by Single-domain Antibodies Targeting the Active Site.
- Source :
-
Journal of Molecular Biology . Feb2020, Vol. 432 Issue 4, p1109-1125. 17p. - Publication Year :
- 2020
-
Abstract
- The extreme potency of the plant toxin, ricin, is due to its enzymatic subunit, RTA, which inactivates mammalian ribosomes with near-perfect efficiency. Here we characterized, at the functional and structural levels, seven alpaca single-domain antibodies (V H Hs) previously reported to recognize epitopes in proximity to RTA's active site. Three of the V H Hs, V2A11, V8E6, and V2G10, were potent inhibitors of RTA in vitro and protected Vero cells from ricin when expressed as intracellular antibodies ("intrabodies"). Crystal structure analysis revealed that the complementarity-determining region 3 (CDR3) elements of V2A11 and V8E6 penetrate RTA's active site and interact with key catalytic residues. V2G10, by contrast, sits atop the enzymatic pocket and occludes substrate accessibility. The other four V H Hs also penetrated/occluded RTA's active site, but lacked sufficient binding affinities to outcompete RTA-ribosome interactions. Intracellular delivery of high-affinity, single-domain antibodies may offer a new avenue in the development of countermeasures against ricin toxin.toxin, antibody, structure, intracellular Image 1 • Ricin's catalytic subunit (RTA) inactivates ribosome with high efficiency. • Alpaca single-domain antibodies (VHH) that target RTA's active site identified. • Intracellular expression (intrabody) of VHHs neutralizes ricin toxin. • Seven crystal structures of VHH-RTA complexes reported. • Results pave the way for novel antitoxin therapies. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00222836
- Volume :
- 432
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Journal of Molecular Biology
- Publication Type :
- Academic Journal
- Accession number :
- 141943489
- Full Text :
- https://doi.org/10.1016/j.jmb.2020.01.006