A fragment of the Escherichia coli ClpB heat-shock protein is a micromolar melanocortin 1 receptor agonist

• Published in: Bioorganic & medicinal chemistry letters 2015-11, Vol.25 (22), p.5306-5308
• Main Authors: Ericson, Mark D., Schnell, Sathya M., Freeman, Katie T., Haskell-Luevano, Carrie
• Format: Article
• Language: English
• Subjects: AlphaScreen® cAMP assay; Amino Acid Sequence; Animals; ClpB heat shock protein; Endopeptidase Clp; Escherichia coli; Escherichia coli Proteins - chemical synthesis; Escherichia coli Proteins - pharmacology; Heat-Shock Proteins - chemical synthesis; Heat-Shock Proteins - pharmacology; HEK293 Cells; Humans; Ligands; Melanocortin receptors; Mice; NDP-MSH; Peptide Fragments - chemical synthesis; Peptide Fragments - pharmacology; Receptor, Melanocortin, Type 1 - agonists; α-MSH
• ISSN: 0960-894X; 1464-3405
• DOI: 10.1016/j.bmcl.2015.09.046

[Display omitted] The melanocortin system consists of five receptor subtypes (MC1–5R), endogenous agonists derived from the proopiomelanocortin gene transcript, and the antagonists agouti and agouti-related protein. The Escherichia coli heat shock protein ClpB has previously been described as an antigen mimetic to the endogenous melanocortin agonist α-MSH. Herein, we investigated if a fragment of the ClpB protein could directly signal through the melanocortin receptors. We synthesized a complementary fragment of the ClpB protein that partially aligned with α-MSH. Pharmacological assessment of this fragment resulted in no antagonist activity at the MC3R or the MC4R and no agonist activity at the MC4R. Partial receptor activation was observed for the MC3R and MC5R at 100μM concentrations. This fragment was shown to be a full micromolar MC1R agonist and may serve as a template for future research into selective MC1R ligands.