[Metabolic engineering of Escherichia coli for thymidine production].

Thymidine, as a crucial precursor of anti-AIDS drugs (e.g., zidovudine and stavudine), has wide application potential in the pharmaceutical industry. In this study, we introduced the thymidine biosynthesis pathway into the wild-type Escherichia coli MG1655 by systems metabolic engineering to improve the thymidine production in E. coli. Firstly, deoA, tdk, udp, rihA, rihB, and rihC were successively deleted to block the thymidine degradation pathway and salvage pathway in the wild-type E. coli MG1655. Then, the pyrimidine nucleoside operons from Bacillus subtilis F126 were introduced to enlarge the metabolic flux of the uridylic acid synthesis pathway. Finally, the expression of uridylate kinase, ribonucleoside diphosphate reductase, thymidine synthase, and 5'-nucleotidase in the thymidine biosynthesis pathway was optimized to enhance the metabolic flux from uridylic acid to thymidine. The engineered THY6-2 strain produced 11.10 g/L thymidine in a 5 L bioreactor with a yield of 0.04 g/g glucose and productivity of 0.23 g/(L·h). In this study, we constructed a strain that used glucose as the only carbon source for efficient production of thymidine and did not harbor plasmids, which provided a reference for the research on other pyrimidine nucleosides.

Bioinformatics analysis and validation of HAUS6 as a key prognostic gene in squamous cell carcinoma of the tongue.

OBJECTIVE: To explore the expression of HAUS6 in squamous cell carcinoma of the tongue (TSCC) and its relationship with the clinicopathological features of patients, and to further provide new ideas and therapeutic targets for curing TSCC. DESIGN: The Cancer Genome Atlas (TCGA) database was used to screen for differentially expressed genes (DEGs) between TSCC and normal tissues and survival analysis. DEGs of HAUS6 were screened and analyzed for GO, KEGG and GSEA enrichment. Exploring the correlation of HAUS6 with immune cell infiltration and immune checkpoint-related genes. The expression of HAUS6 in tumor and paraneoplastic tissues was confirmed by immunohistochemistry and Western Blot. RESULTS: Analysis of the TCGA database results showed that expression of HAUS6 mRNA was significantly enhanced and correlated with overall survival (OS, p < 0.05) in TSCC. HAUS6 expression correlated with the level of immune cell infiltration and immune checkpoint-related genes. Immunohistochemistry and Western Blot confirmed that the expression level of HAUS6 protein was significantly higher in tumor tissues than in paraneoplastic tissues, and that tumor size and hypo-differentiation were higher in the HAUS6 high expression group than in the low expression group in TSCC (p < 0.05). CONCLUSIONS: In conclusion, these analyses suggest that HAUS6 can act as an independent predictor of prognosis (p < 0.05) and high HAUS6 expression is strongly associated with poor prognosis.