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Science 4 August 1989:
Vol. 245. no. 4917, pp. 522 - 524
DOI: 10.1126/science.2667139
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Articles

Science, Vol 245, Issue 4917, 522-524
Copyright © 1989 by American Association for the Advancement of Science

articles

Triggering of allostery in an enzyme by a point mutation: ornithine transcarbamoylase

LC Kuo, I Zambidis, and C Caron

Department of Chemistry, Metcalf Center for Science and Engineering, Boston University, MA 02215.

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.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Temperature Adaptation of Glutathione S-Transferase P1-1. A CASE FOR HOMOTROPIC REGULATION OF SUBSTRATE BINDING.
A. M. Caccuri, G. Antonini, P. Ascenzi, M. Nicotra, M. Nuccetelli, A. P. Mazzetti, G. Federici, M. L. Bello, and G. Ricci (1999)
J. Biol. Chem. 274, 19276-19280
   Abstract »    Full Text »    PDF »
Substrate-induced conformational change in a trimeric ornithine transcarbamoylase.
Y. Ha, M. T. McCann, M. Tuchman, and N. M. Allewell (1997)
PNAS 94, 9550-9555
   Abstract »    Full Text »    PDF »
Site-directed Mutagenesis of Human Glutathione Transferase P1-1.
G. Ricci, M. Lo Bello, A. M. Caccuri, A. Pastore, M. Nuccetelli, M. W. Parker, and G. Federici (1995)
J. Biol. Chem. 270, 1243-1248
   Abstract »    Full Text »    PDF »
Cooperativity induced by a single mutation at the subunit interface of a dimeric enzyme: glutathione reductase.
N. Scrutton, M. Deonarain, A Berry, and R. Perham (1992)
Science 258, 1140-1143
   Abstract »    PDF »


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