Physiological characterization of a pyrimidine auxotroph exposes link between uracil phosphoribosyltransferase regulation and riboflavin production in Ashbya gossypii.

Physiological characterization of a pyrimidine auxotroph exposes link between uracil phosphoribosyltransferase regulation and riboflavin production in Ashbya gossypii. N Biotechnol. 2018 Dec 24;: Authors: Silva R, Aguiar TQ, Oliveira C, Domingues L Abstract The blockage of the de novo pyrimidine biosynthetic pathway at the orotidine-5'-phosphate decarboxylase level was previously demonstrated to affect riboflavin production in the industrial producer fungus Ashbya gossypii. However, the molecular basis for the unusual sensitivity to uracil displayed by the pyrimidine auxotroph A. gossypii Agura3 was unknown. Here, uridine was shown to be the only intermediate of the pyrimidine salvage pathway able to fully restore this mutant's growth. Conversely, uracil, which is routinely used to rescue pyrimidine auxotrophs, had a dose-dependent growth-inhibitory effect. Uracil phosphoribosyltransferase (UPRT) is the pyrimidine salvage pathway enzyme responsible for converting uracil to uridine monophosphate in the presence of phosphoribosyl pyrophosphate (PRPP). Characterization of the A. gossypii UPRT, as produced and purified from Escherichia coli, revealed that uracil concentrations above 1 mM negatively affected its activity, thus explaining the hypersensitivity of the Agura3 mutant to uracil. Accordingly, overexpression of the AgUPRT encoding-gene in A. gossypii Agura3 led to similar growth on rich medium containing 5 mM uracil or uridin...
Source: New Biotechnology - Category: Biotechnology Authors: Tags: N Biotechnol Source Type: research