Loss of Binding Capabilities in an Ecologically Important Odorant Receptor of the Fall Armyworm, Spodoptera frugiperda, by a Single Point Mutation

Abstract

Olfaction plays a crucial role in locating food sources, mates, and spawning sites in the fall armyworm (FAW), Spodoptera f rugiperda (Lepidoptera: Noctuidae). In the current study, SfruOR14, a highly conserved odorant receptor (OR) in lepidopteran species, was newly uncovered in S. f rugiperda. In two-electrode voltage clamp recordings, the SfruOR14/Orco complex was narrowly tuned to six volatile compounds including phenylacetaldehyde (PAA), benzaldehyde, heptaldehyde, (E)-2-hexen-1-al, cinnamaldehyde, and 2-phenylethanol, among which PAA showed the strongest binding affinity. Subsequent homology modeling and molecular docking revealed that Phe79, His83, Tyr149, Pro176, Gln177, Leu202, and Thr348 in SfruOR14 were the key binding residues against the six ligands. Finally, as a result of site-directed mutagenesis, the SfruOR14 His83Ala mutant completely lost its binding capabilities toward all ligands. Taken together, our findings provide valuable insights into understanding the interaction between SfruOR14 and the chemical ligands including PAA, which can help to design novel olfactory modulators for pest control.

Female-Biased Odorant Receptor MmedOR48 in the Parasitoid Microplitis mediator Broadly Tunes to Plant Volatiles

“…These findings indicate that residues Thr142, Gln80, Gln282, and Thr312 together formed the key binding site in the active pocket for the aldehyde ligands. Previous studies have demonstrated the importance of a single key residue, such as His83 of the SfruOR14 in the fall armyworm Spodoptera frugiperda, in biasing the receptor against certain ligands . Similarly, the Ser209 residue was found to be essential for the OachOR16 binding with camphor in Orthaga achatina .…”

“…Site-directed mutagenesis was performed based on docking analysis. Three mutant variants were designed . Type I: Thr142 replaced with Ala; Type II: Gln80, Gln282, and Thr312 replaced with Ala; Type III: All four residues (Thr142, Gln80, Gln282, and Thr312) were replaced with Ala. Wild-type and mutant MmedOR48 constructs in pT7TS were synthesized by Sangon Biotech (Shanghai, China).…”