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Title: Structural analysis of nested neutralizing and non-neutralizing B cell epitopes on ricin toxin's enzymatic subunit

Journal Article · · Proteins
DOI:https://doi.org/10.1002/prot.25062· OSTI ID:1267468
 [1];  [2];  [1];  [2];  [3];  [4]
  1. New York Structural Biology Center, New York, NY (United States)
  2. New York State Dept. of Health, Albany, NY (United States)
  3. Tufts Cummings School of Veterinary Medicine, North Grafton, MA (United States)
  4. New York State Dept. of Health, Albany, NY (United States); Univ. at Albany, Albany, NY (United States)
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In this report, we describe the X–ray crystal structures of two single domain camelid antibodies (VHH), F5 and F8, each in complex with ricin toxin's enzymatic subunit (RTA). F5 has potent toxin–neutralizing activity, while F8 has weak neutralizing activity. F5 buried a total of 1760 Å2 in complex with RTA and made contact with three prominent secondary structural elements: α–helix B (Residues 98–106), β–strand h (Residues 113–117), and the C–terminus of α–helix D (Residues 154–156). F8 buried 1103 Å2 in complex with RTA that was centered primarily on β–strand h. As such, the structural epitope of F8 is essentially nested within that of F5. All three of the F5 complementarity determining regions CDRs were involved in RTA contact, whereas F8 interactions were almost entirely mediated by CDR3, which essentially formed a seventh β–strand within RTA's centrally located β–sheet. A comparison of the two structures reported here to several previously reported (RTA–VHH) structures identifies putative contact sites on RTA, particularly α–helix B, associated with potent toxin–neutralizing activity. Here, this information has implications for rational design of RTA–based subunit vaccines for biodefense.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Inst. of Allergy and Infectious Diseases
Grant/Contract Number:
AC02‐98CH10886; HHSN272201400021C
OSTI ID:
1267468
Journal Information:
Proteins, Vol. 84, Issue 8; ISSN 0887-3585
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 13 works
Citation information provided by
Web of Science

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Cited By (6)

Sensitivity of Kupffer cells and liver sinusoidal endothelial cells to ricin toxin and ricin toxin–Ab complexes journal July 2019
Contribution of an unusual CDR2 element of a single domain antibody in ricin toxin binding affinity and neutralizing activity journal July 2018
High-Resolution Epitope Positioning of a Large Collection of Neutralizing and Nonneutralizing Single-Domain Antibodies on the Enzymatic and Binding Subunits of Ricin Toxin journal October 2017
High-Definition Mapping of Four Spatially Distinct Neutralizing Epitope Clusters on RiVax, a Candidate Ricin Toxin Subunit Vaccine journal October 2017
Nanobody Technology: A Versatile Toolkit for Microscopic Imaging, Protein–Protein Interaction Analysis, and Protein Function Exploration journal July 2017
A Collection of Single-Domain Antibodies that Crowd Ricin Toxin’s Active Site journal December 2018

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Related Subjects

59 BASIC BIOLOGICAL SCIENCES
toxin
antibody
epitope
neutralizing