Definition of a saxitoxin (STX) binding code enables discovery and characterization of the anuran saxiphilin family
Abstract
American bullfrog ( Rana castesbeiana ) saxiphilin ( Rc Sxph) is a high-affinity “toxin sponge” protein thought to prevent intoxication by saxitoxin (STX), a lethal bis-guanidinium neurotoxin that causes paralytic shellfish poisoning (PSP) by blocking voltage-gated sodium channels (Na V s). How specific Rc Sxph interactions contribute to STX binding has not been defined and whether other organisms have similar proteins is unclear. Here, we use mutagenesis, ligand binding, and structural studies to define the energetic basis of Sxph:STX recognition. The resultant STX “recognition code” enabled engineering of Rc Sxph to improve its ability to rescue Na V s from STX and facilitated discovery of 10 new frog and toad Sxphs. Definition of the STX binding code and Sxph family expansion among diverse anurans separated by ∼140 My of evolution provides a molecular basis for understanding the roles of toxin sponge proteins in toxin resistance and for developing novel proteins to sense or neutralize STX and related PSP toxins.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 24, 2022
- Source ID
- 10.1073/pnas.2210114119
Entities
People
- Aurora Alvarez-buylla
- Daniel L Minor
- Dave Ramirez
- Fayal Abderemane-ali
- Holly S. Hajare
- Justin Du Bois
- Lauren A. O'Connell
- Maximiliana Bogan
- Sandra Zakrzewska
- Zhou Chen
Organizations
- American Heart Association
- Defense Threat Reduction Agency
- Division of Graduate Education
- Howard Hughes Medical Institute
- National Institute of General Medical Sciences
- National Science Foundation
- Stanford University
- University of California