Abstract
Background & Objective: Contryphan-Bt is a D-tryptophan-containing disulfide-constrained decapeptide recently isolated from the venom of Conus betulinus. The molecular targets of contryphans are controversial, and the identification of its interacting proteins may be of great importance.
Methods: His-tag pull-down assays were performed to investigate intracellular binding proteins of contryphan-Bt from rat brain lysate. Bt-Acp-[His]6, a contryphan-Bt derivative containing hexahistidine tag, was synthesized and used as the bait. As a control, Acp-[His]6 was used to exclude nonspecific bindings.
Results: Glutamine synthetase was identified as a potential contryphan-Bt binding protein by pull-- down assays and subsequent LC-MS/MS. The binding of contryphan-Bt to glutamine synthetase was confirmed and determined using microscale thermophoresis, with a Kd of 74.02 ± 2.8 μM. The binding did not affect glutamine synthetase activity, suggesting that the interaction site was distinct from the catalytic center.
Conclusion: Glutamine synthetase was identified as a novel contryphan-Bt binding protein. This is the first report in which the conopeptide binds to an intracellular protein.
Keywords: Conopeptides, contryphans, contryphan-Bt, His-tag pull-down, glutamine synthetase, microscale thermophoresis.
Graphical Abstract
Related Journals
Current Protein & Peptide Science
Related Books
Frontiers in Protein and Peptide Sciences
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