Related Experiment Video
Updated: May 11, 2026

Extremely Rapid and Specific Metabolic Labelling of RNA In Vivo with 4-Thiouracil (Ers4tU)
Published on: August 22, 2019
PyrG is required for maintaining stable cellular uracil level and normal sporulation pattern under excess uracil
Xianyun Sun1, Jufen Zhu, Li Bao
1State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100080, China.
Abstract:
Tight control of the intracellular uracil level is believed to be important to reduce the occurrence of uracil incorporation into DNA. The pyrG gene of Aspergillus nidulans encodes orotidine 5'-phosphate decarboxylase, which catalyzes the conversion of orotidine monophosphate (OMP) to uridine monophosphate (UMP). In this study, we found that pyrG is critical for maintaining uracil at a low concentration in A. nidulans cells in the presence of exogenous uracil. Excess uracil and its derivatives had a stronger inhibitory effect on the growth of the pyrG89 mutant with defective OMP decarboxylase activity than on the growth of wild type, and induced sexual development in the pyrG89 mutant but not in wild type. Analysis of transcriptomic responses to excess uracil by digital gene expression profiling (DGE) revealed that genes related to sexual development were transcriptionally activated in the pyrG89 mutant but not in wild type. Quantitative analysis by HPLC showed that the cellular uracil level was 6.5 times higher in the pyrG89 mutant than in wild type in the presence of exogenous uracil. This study not only provides new information on uracil recycling and adaptation to excess uracil but also reveals the potential effects of OMP decarboxylase on fungal growth and development.
Related Concept Videos
Biosynthesis of Nucleic Acids
Stringent Response in E. coli
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
Biosynthesis of Polysaccharides
Gene Regulation During Sporulation
The Unfolded Protein Response

