9FRQ | pdb_00009frq

Solution structure of Tx33.1 from Conus textile

PDB DOI: https://doi.org/10.2210/pdb9FRQ/pdb
BMRB: 34921

Classification: TOXIN
Organism(s): Conus textile
Expression System: Escherichia coli
Mutation(s): No

Deposited: 2024-06-19 Released: 2025-07-02
Deposition Author(s): Ellgaard, L., Khilji, M.S., Hackney, C.M., Teilum, K.
Funding Organization(s): Novo Nordisk Foundation

Experimental Data Snapshot

Method: SOLUTION NMR
Conformers Calculated: 100
Conformers Submitted: 20
Selection Criteria: structures with the lowest energy

wwPDB Validation 3D Report Full Report

This is version 1.1 of the entry. See complete history.

Literature

Structural similarities reveal an expansive conotoxin family with a two-finger toxin fold.

Khilji, M.S., Hackney, C.M., Koch, T.L., Hone, A.J., Rogalski, A., Watkins, M., Tun, J., McIntosh, J.M., Olivera, B., Safavi-Hemami, H., Teilum, K., Ellgaard, L.

(2025) Protein Sci 34: e70333-e70333

PubMed: 41074857 Search on PubMed Search on PubMed Central
DOI: https://doi.org/10.1002/pro.70333
Primary Citation Related Structures:
9FRQ

PubMed Abstract:
Venomous animals have evolved a diverse repertoire of toxins with considerable pharmaceutical potential. The rapid evolution of peptide toxins, such as the conotoxins produced by venomous marine cone snails, often complicates efforts to infer their evolutionary relationships based solely on sequence information. Structural bioinformatics, however, can provide robust support. Here, we first solve the NMR structure of a macro-conotoxin from the MLSML superfamily, Tx33.1, which is composed of 124 residues, including 12 cysteines. We then apply deep learning-based methods for structure prediction and comparison to identify structural similarities between this toxin and five additional, previously uncharacterized conotoxin superfamilies. Although only three of these superfamilies exhibit sequence homology, a combined approach incorporating structure prediction, structure comparison, and gene structure analysis supports the conclusion that all six superfamilies share a common evolutionary past. The Tx33.1 NMR structure displays similarity to the first two domains of Argos, a secretory protein from Drosophila melanogaster that comprises three domains, each harboring two short β-stranded loops ("fingers"). Consequently, we propose the name "two-finger toxin (2FTX)" fold for this type of domain. Finally, using structure similarity searches, we identify a wide range of 2FTX proteins in protostomes, including non-venom-derived, secretory cone snail proteins. This study demonstrates how structural bioinformatics can be employed to uncover evolutionary relationships among rapidly evolving genes. It simultaneously identifies a large, previously unrecognized group of protostome 2FTX proteins, many of which exhibit close structural similarity to Argos and may perform a similar function in regulating EGFR signaling.

Organizational Affiliation