A covalent peptide inhibitor of RGS4 identified in a focused one-bead, one compound library screen

Regulators of G protein signaling (RGSs) accelerate GTP hydrolysis by Galpha subunits and profoundly inhibit signaling by G protein-coupled receptors (GPCRs). The distinct expression patterns and pathophysiologic regulation of RGS proteins suggest that inhibitors may have therapeutic potential. We r...

Full description

Saved in:
Bibliographic Details
Published in:BMC pharmacology 2009-05, Vol.9 (1), p.9-9, Article 9
Main Authors: Roof, Rebecca A, Roman, David L, Clements, Samuel T, Sobczyk-Kojiro, Katarzyna, Blazer, Levi L, Ota, Shodai, Mosberg, Henry I, Neubig, Richard R
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Cellular signal transduction
Cysteine - chemistry
Drugs
G proteins
Molecular Sequence Data
Peptide Library
Peptides, Cyclic - chemical synthesis
Peptides, Cyclic - chemistry
Peptides, Cyclic - pharmacology
Physiological aspects
Product/Service Evaluations
Protein Conformation
RGS Proteins - antagonists & inhibitors
RGS Proteins - chemistry
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Regulators of G protein signaling (RGSs) accelerate GTP hydrolysis by Galpha subunits and profoundly inhibit signaling by G protein-coupled receptors (GPCRs). The distinct expression patterns and pathophysiologic regulation of RGS proteins suggest that inhibitors may have therapeutic potential. We recently described a focused one-bead, one-compound (OBOC) library screen to identify peptide inhibitors of RGS4. Here we extend our observations to include another peptide with a different mechanism of action. Peptide 5nd (Tyr-Trp-c [Cys-Lys-Gly-Leu-Cys]-Lys-NH2, S-S) blocks the RGS4-Galphao interaction with an IC50 of 28 microM. It forms a covalent, dithiothreitol (DTT) sensitive adduct with a mass consistent with the incorporation of one peptide per RGS. Peptide 5nd activity is abolished by either changing its disulfide bridge to a methylene dithioether bridge, which cannot form disulfide bridges to the RGS, or by removing all cysteines from the RGS protein. However, no single cysteine in RGS4 is completely necessary or sufficient for 5nd activity. Though it has some RGS selectivity, 5nd appears to be a partially random cysteine modifier. These data suggest that it inhibits RGS4 by forming disulfide bridges with the protein.
ISSN:1471-2210
1471-2210
DOI:10.1186/1471-2210-9-9