In addition, four dihydroorotase genes, two dihydroorotate dehydrogenase genes, three uridine monophosphate synthetase genes, two 5'-nucleotidase genes, one uridine nucleosidase gene, one udk gene, two UMP-CMP kinase genes, one ndk gene, one apyrase gene, one ITPA gene, one CTP synthase gene, and one cdd gene were successfully cloned (Figure S4, Supporting Information).
Dihydroorotate dehydrogenase, uridine nucleosidase, UMP-CMP kinase, and ITPA genes also played key roles in pyrimidine nucleoside biosynthesis.
Based on the results of the differential expression analysis, the uridine nucleosidase gene was significantly upregulated and uridine nucleosidase was considered as a key enzyme involved in the biosynthetic pathway of pyrimidine nucleosides.
sinensis based on biosynthetic pathway and differential expression analysis, the uridine production reached 5.04 mg/g with an increase of 28.6% when 2 mg/mL ribose was added, while uridine production reached 10.83 mg/g with a rise of 176.3% when 0.3 mg/mL uracil was added, indicating that the product inhibition for uridine nucleosidase by uracil was stronger than that by ribose.
In addition, dihydroorotate dehydrogenase, uridine nucleosidase, UMP-CMP kinase, and ITPA genes involved in pyrimidine nucleoside biosynthesis were found upregulated 4.53-fold, 10.63-fold, 4.26-fold, and 5.98-fold, respectively.