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Mutations in the tryptophan operon allow PurF-independent thiamine synthesis by altering flux in vivo

Ramos, Itzel and Vivas, E. I. and Downs, D. M. (2007) Mutations in the tryptophan operon allow PurF-independent thiamine synthesis by altering flux in vivo. Journal of Bacteriology . ISSN 0021-9193. doi:10.1128/JB.00582-07.

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Phosphoribosyl amine (PRA) is an intermediate in purine biosynthesis and also required for thiamine biosynthesis in Salmonella enterica. PRA is normally synthesized by phosphoribosyl pyrophosphate (PRPP) amidotransferase, a high-turnover enzyme of the purine biosynthetic pathway encoded by purF. However, PurF-independent PRA synthesis has been observed in strains with different genetic backgrounds and growing under diverse conditions. Genetic analysis has shown that the anthranilate synthase-phosphoribosyltransferase (AS-PRT) enzyme complex, involved in the synthesis of tryptophan, can play a role in the synthesis of phosphoribosyl amine (PRA). This work describes the in vitro synthesis of PRA in the presence of the purified components of AS-PRT complex. Results from in vitro assays and in vivo studies indicate the cellular accumulation of phosphoribosyl anthranilate can result in non-enzymatic PRA formation sufficient for thiamine synthesis. These studies have uncovered a mechanism used by cells to redistribute metabolites to ensure thiamine synthesis, and may define a general paradigm of metabolic robustness.

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Additional Information:Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. JB Accepts, published online ahead of print on 8 June 2007.
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ID Code:8812
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Deposited On:19 Sep 2007
Last Modified:08 Nov 2021 20:53

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