Structural basis of ligand specificity and channel activation in an insect gustatory receptor

Gustatory Receptors (GRs) are critical for insect chemosensation and are potentialtargets for controlling pests and disease vectors, making their structural investigation avital step towards such applications. We present structures of Bombyx mori Gr9(BmGr9), a fructose-gated cation channel, in agonist-free and fructose-bound states.BmGr9 forms a tetramer similar to distantly related insect Olfactory Receptors (ORs).Upon fructose binding, BmGr9’s channel gate opens through helix S7b movements. Incontrast to ORs, BmGR9’s ligand-binding pocket, shaped by a kinked helix S4 and ashorter extracellular S3-S4 loop, is larger and solvent accessible in both agonist-freeand fructose-bound states. Also unlike ORs, fructose binding by BmGr9 involves helixS5 and a pocket lined with aromatic and polar residues. Structure-based sequencealignments reveal distinct patterns of ligand-binding pocket residue conservation in GRsubfamilies associated with different ligand classes. These data provide insight i..., , , Molecular dynamics (MD) simulations and multiple sequence alignments in the paper \"Structural basis of ligand specificity and channel activation in an insect gustatory receptor\".

Alignments and simulations created and performed by Sanket Walujkar under the supervision of Prof. Rachelle Gaudet.

## Description of the data and file structure

There are four FASTA files containing four different multiple sequence alignments.

1. ORs-uniref50-alignment.fasta: Full length alignment of 3885 odorant receptor (OR) sequences from the Uniref50 database.
2. ORs-uniref50-alignment-MhOr5-mapped.fasta: Alignment of the same 3885 OR sequences but only columns corresponding to *Machilis hrabei* OR5 (PDB: 7LIC).
3. GRs-uniref50-alignment.fasta: Full length alignment of 1854 gustatory receptor (GR) sequences from the Uniref50 database.
4. GRs-uniref50-alignment-BmGr9-mapped.fasta: Alignment of the same 1854 GR sequences but only columns corresponding to *Bombyx mori* Gr9 (PDB: 8VC1, 8VC2; Uniprot: B...