Inhibition of ghrelin O-acyltransferase (GOAT) by octanoylated pentapeptides

The discovery of ghrelin O-acyltransferase (GOAT) opens the way to the design of drugs that block the attachment of an octanoyl group to the appetite-stimulating peptide hormone ghrelin, potentially preventing obesity. Here, we develop a biochemical assay that uses membranes from insect cells infect...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2008-08, Vol.105 (31), p.10750-10755
Main Authors: Yang, Jing, Zhao, Tong-Jin, Goldstein, Joseph L, Brown, Michael S
Format: Article
Language:English
Subjects:
Acyltransferases - antagonists & inhibitors
Acyltransferases - metabolism
Amino acids
Animals
Baculoviridae
Biological Assay - methods
Biological Sciences
Caprylates - metabolism
Cell membranes
Chromatography
Endocrine cells
Enzymes
Experimental procedures
Ghrelin - metabolism
Goats
Humans
Immunoblotting
Membrane proteins
Membranes
Membranes - metabolism
Mice
Obesity
Obesity - prevention & control
Peptides
Peptides - metabolism
Proteins
Rodents
Tritium
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Summary:The discovery of ghrelin O-acyltransferase (GOAT) opens the way to the design of drugs that block the attachment of an octanoyl group to the appetite-stimulating peptide hormone ghrelin, potentially preventing obesity. Here, we develop a biochemical assay that uses membranes from insect cells infected with baculovirus encoding mouse GOAT. The GOAT-containing membranes transferred the [³H]octanoyl group from [³H]octanoyl CoA to recombinant proghrelin in vitro. Transfer depended on the serine at residue 3 of proghrelin, which is the known site of acylation. GOAT also transferred [³H]octanoyl to a pentapeptide containing only the N-terminal five amino acids of proghrelin. GOAT activity could be inhibited by an octanoylated ghrelin pentapeptide, and its potency was enhanced 45-fold when the octanoylated serine-3 was replaced by octanoylated diaminopropionic acid. The data suggest that GOAT is subjected to end-product inhibition and this inhibition is better achieved with substrates having the octanoyl group attached through an amide linkage rather than the corresponding ester. These insights may facilitate the future design of useful inhibitors of GOAT.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0805353105