Triggering of allostery in an enzyme by a point mutation: ornithine transcarbamoylase.
Science
; 245(4917): 522-4, 1989 Aug 04.
Article
en En
| MEDLINE
| ID: mdl-2667139
ABSTRACT
The origin of allostery is an unanswered question in the evolution of complex regulatory proteins. Anabolic ornithine transcarbamoylase, a trimer of identical subunits, is not an allosteric enzyme per se. However, when the active-site residue arginine-106 of the Escherichia coli enzyme is replaced with a glycine through site-directed mutagenesis, the resultant mutant enzyme manifests substrate cooperativity that is absent in the wild-type enzyme. Both homotropic and heterotropic interactions occur in the mutant enzyme. The initial velocity saturation curves of the substrates, carbamoyl phosphate and L-ornithine, conform to the Hill equation. The observed cooperativity depends on substrate but not enzyme concentration. The finding underscores the possibility that a single mutation of the enzyme in the cell could turn transcarbamoylation into a regulatory junction in the biosynthesis of L-arginine and urea.
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Bases de datos:
MEDLINE
Asunto principal:
Ornitina Carbamoiltransferasa
/
Escherichia coli
/
Mutación
Idioma:
En
Revista:
Science
Año:
1989
Tipo del documento:
Article