Recombinant Human URA5 protein

The URA5 gene encodes orotate phosphoribosyltransferase (OPRTase), a key enzyme in the pyrimidine biosynthesis pathway that catalyzes the conversion of orotic acid to orotidine 5'-monophosphate. In many fungi, including *Saccharomyces cerevisiae* and pathogenic species like *Cryptococcus neoformans*, URA5 serves as a selectable marker in genetic studies. Strains with ura5 mutations are auxotrophic for uracil, enabling researchers to use uracil-deficient media for selection during transformation or gene-editing experiments.

Recombinant URA5 protein is typically produced by cloning the URA5 coding sequence into expression vectors (e.g., *E. coli* or yeast systems) followed by protein purification. This engineered protein retains enzymatic activity and is widely utilized to study fungal metabolism, gene function, and host-pathogen interactions. In pathogenic fungi, URA5 is of particular interest as a potential antifungal drug target due to its essential role in survival and virulence.

Additionally, the URA5/ura5 system is employed as a reporter in molecular biology. For example, complementation assays using recombinant URA5 can validate gene function in ura5-deficient strains. Its application extends to CRISPR-Cas9 editing, where restored uracil prototrophy indicates successful genetic modification. Researchers also use URA5-deficient strains to investigate immune responses in animal models, as attenuated pathogens help dissect virulence mechanisms.

Despite its utility, URA5-based selection has limitations, including background growth in certain media and species-specific sequence variations requiring customized cloning. Ongoing studies optimize recombinant URA5 production and explore its structural features to improve biotechnological and therapeutic applications. This protein remains a cornerstone in fungal genetics and antimicrobial development. (Word count: 398)