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Dihydrodipicolinate synthase (DHDPS) from Escherichia coli displays partial mixed inhibition with respect to its first substrate, pyruvate
- Source :
-
Biochimie . Apr2004, Vol. 86 Issue 4/5, p311-315. 5p. - Publication Year :
- 2004
-
Abstract
- Dihydrodipicolinate synthase (DHDPS, E.C. 4.2.1.52) mediates the first unique reaction of (S)-lysine biosynthesis in plants and microbes—the condensation of (S)-aspartate-β-semialdehyde ((S)-ASA) and pyruvate. It has been shown that DHDPS is partially feedback inhibited by (S)-lysine; it is suggested that this mechanism regulates flux through the DAP biosynthetic pathway. Others have characterised DHDPS from Escherichia coli with respect to (S)-lysine inhibition. They have concluded that, with respect to pyruvate, the first substrate of the reaction, DHDPS shows uncompetitive inhibition: as such, they further suggest that (S)-lysine inhibits DHDPS via interaction with the binding site for the second substrate, (S)-ASA. Yet, this finding is based on the assumption that (S)-lysine is a fully uncompetitive inhibitor. In light of crystallographic studies, which lead to the proposal that (S)-lysine affects the putative proton-relay of DHDPS, we re-evaluated the inhibition mechanism of DHDPS with respect to (S)-lysine by incorporating the observed hyperbolic inhibition. Our data showed that lysine is not an uncompetitive inhibitor, but a mixed inhibitor when pyruvate and (S)-lysine concentrations were varied. Thus, consistent with the crystallographic data, (S)-lysine must have an effect on the initial steps of the DHDPS reaction, including the binding of pyruvate and Schiff base formation. [Copyright &y& Elsevier]
- Subjects :
- *ESCHERICHIA coli
*PYRUVATES
*PLANT product synthesis
*BIOSYNTHESIS
Subjects
Details
- Language :
- English
- ISSN :
- 03009084
- Volume :
- 86
- Issue :
- 4/5
- Database :
- Academic Search Index
- Journal :
- Biochimie
- Publication Type :
- Academic Journal
- Accession number :
- 13389090
- Full Text :
- https://doi.org/10.1016/j.biochi.2004.03.008