Recombinant Lucihormetica verrucosa Sulfakinin-1

Introduction to Sulfakinins

Sulfakinins (SKs) are neuropeptides structurally and functionally analogous to vertebrate gastrin/cholecystokinins. They regulate feeding behavior, energy metabolism, and digestive processes in insects through G-protein-coupled receptors (GPCRs) . These peptides are characterized by a conserved C-terminal motif (DY(SO3)GHM/LRFamide), with the sulfated tyrosine residue critical for receptor binding and activity .

While no studies explicitly describe recombinant Lucihormetica verrucosa Sulfakinin-1 (LvSK-1), research on sulfakinins in related insects provides a framework for understanding its potential structure and function.

Functional Homology and Comparative Analysis

Sulfakinins across insect species share conserved roles in satiety signaling and metabolic regulation. For example:

• SK in *Dendroctonus armandi*:

  • Reduces feeding and body weight upon injection.

  • Elevates hemolymph trehalose while decreasing glycogen and free fatty acids .

• SK in *Bombyx mori*:

  • Binds BNGR-A9 receptor, reducing food intake and body weight.

  • Increases hemolymph trehalose via Gαq-mediated signaling .

Implications for Lucihormetica verrucosa Sulfakinin-1

L. verrucosa (warty glowspot cockroach) is noted for its sexual dimorphism and carotenoid-dependent pronotal spots . While no studies directly address its sulfakinin system, extrapolation from related species suggests:

• Structural Predictions:

  • Likely retains the DY(SO3)GHMRFamide motif.

  • Sulfation at tyrosine is critical for receptor interaction.

• Functional Hypotheses:

  • Potential roles in appetite suppression, energy homeostasis, or stress responses.

  • May interact with GPCRs analogous to BNGR-A9 or DaSKR.

Methodological Insights for Recombinant Production

Recombinant SK production typically involves:

1. Gene Cloning: Amplify SK precursor cDNA from target species.

2. Peptide Synthesis: Use E. coli or yeast systems for expression, followed by sulfation via tyrosylprotein sulfotransferases .

3. Functional Assays:

   • Receptor activation tests (e.g., IP3/Ca²⁺ flux in HEK293 cells).

   • In vivo feeding assays (e.g., body weight tracking post-injection).

Research Gaps and Future Directions

• Unresolved Questions:

  • Sequence and receptor specificity of LvSK-1.

  • Sulfation efficiency in recombinant systems.

• Potential Applications:

  • Pest control via appetite suppression.

  • Metabolic studies in cockroach models.