Unmasking a functional allosteric domain in an allosterically nonresponsive carbamoyl-phosphate synthetase

Binnur Eroglu, Susan G. Powers-Lee

Research output: Contribution to journalArticle

Abstract

Although carbamoyl-phosphate synthetases (CPSs) share sequence identity, multidomain structure, and reaction mechanism, they have varying physiological roles and allosteric effectors. Escherichia coli CPS (eCPS) provides CP for both arginine and pyrimidine nucleotide biosynthesis and is allosterically regulated by metabolites from both pathways, with inhibition by UMP and activation by IMP and ornithine. The arginine-specific CPS from Saccharomyces cerevisiae (sCPS), however, apparently responds to no allosteric effectors. We have designed and analyzed a chimeric CPS (chCPS, in which the C-terminal 136 residues of eCPS were replaced by the corresponding residues of sCPS) to define the structural basis for the allosteric nonresponsiveness of sCPS and thereby provide insight into the mechanism for allosteric selectivity and responsiveness in the other CPSs. Surprisingly, ornithine and UMP each had a significant effect on chCPS activity, and did so at concentrations that were similar to those effective for eCPS. We further found that sCPS bound both UMP and IMP and that chCPS bound IMP, although none of these interactions led to changes in enzymatic activity. These findings strongly suggest that the nonresponsive sCPS is not able to communicate occupancy of the allosteric site to the active site but does contain a latent allosteric interaction domain.

Original languageEnglish (US)
Pages (from-to)45466-45472
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number47
DOIs
StatePublished - Nov 22 2002
Externally publishedYes

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Carbamyl Phosphate
Ligases
Yeast
Saccharomyces cerevisiae
Uridine Monophosphate
Inosine Monophosphate
Escherichia coli
Ornithine
Pyrimidine Nucleotides
Allosteric Site
Biosynthesis
Metabolites
Arginine
Catalytic Domain
Chemical activation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Unmasking a functional allosteric domain in an allosterically nonresponsive carbamoyl-phosphate synthetase. / Eroglu, Binnur; Powers-Lee, Susan G.

In: Journal of Biological Chemistry, Vol. 277, No. 47, 22.11.2002, p. 45466-45472.

Research output: Contribution to journalArticle

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