Chemical Bypass of General Base Catalysis in Hedgehog Protein Cholesterolysis Using a Hyper-Nucleophilic Substrate.
J Am Chem Soc
; 140(3): 916-918, 2018 01 24.
Article
en En
| MEDLINE
| ID: mdl-28930454
ABSTRACT
Proteins in the hedgehog family undergo self-catalyzed endoproteolysis involving nucleophilic attack by a molecule of cholesterol. Recently, a conserved aspartate residue (D303, or D46) of hedgehog was identified as the general base that activates cholesterol during this unusual autoprocessing event; mutation of the catalyzing functional group (D303A) reduces activity by >104-fold. Here we report near total rescue of this ostensibly dead general base mutant by a synthetic substrate, 3ß-hydroperoxycholestane (3HPC) in which the sterol -OH group is replaced by the hyper nucleophilic -OOH group. Other hedgehog point mutants at D303, also unreactive with cholesterol, accepted 3HPC as a substrate with the rank order WT > D303A ≈ D303N â« D303R, D303E. We attribute the revived activity with 3-HPC to the α-effect, where tandem electronegative atoms exhibit exceptionally high nucleophilicity despite relatively low basicity.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Colestanos
/
Colesterol
/
Proteínas de Drosophila
/
Drosophila melanogaster
/
Proteínas Hedgehog
Límite:
Animals
Idioma:
En
Revista:
J Am Chem Soc
Año:
2018
Tipo del documento:
Article
País de afiliación:
Estados Unidos