Clostridioides difficile exploits xanthine and uric acid as nutrients by utilizing a selenium-dependent catabolic...

Area of Science:

• Microbiology
• Biochemistry
• Trace Element Metabolism

Background:

• Selenium is vital for redox biology, incorporated as selenocysteine or as a cofactor in selenium-dependent molybdenum hydroxylases (SDMHs).
• SDMHs in purinolytic clostridia degrade purines like hypoxanthine, xanthine, and uric acid for carbon and nitrogen.
• The genes governing selenium cofactor insertion and maturation in SDMHs are largely uncharacterized.

Purpose of the Study:

• To characterize the selenium utilization pathway in Clostridioides difficile, a model organism.
• To investigate the role of this pathway in the catabolism of host-derived purines.
• To identify genes involved in selenium cofactor maturation for SDMHs.

Main Methods:

• Utilized Clostridioides difficile as a genetic model.
• Assessed bacterial growth in minimal medium with and without purines (hypoxanthine, xanthine, uric acid).
• Generated and analyzed selD (selenophosphate synthetase) and yqeB/yqeC deletion mutants using CRISPR-Cas9 technology.

Main Results:

• Clostridioides difficile utilizes hypoxanthine, xanthine, and uric acid for growth.
• selD mutants showed impaired growth on xanthine and uric acid, indicating a selenium-dependent process.
• ΔyqeB mutants exhibited growth defects similar to selD mutants, while ΔyqeC mutants showed no significant phenotype.
• YqeB is implicated in selenium-dependent purine catabolism.

Conclusions:

• YqeB plays a significant role in the selenium-dependent purine catabolism pathway.
• Clostridioides difficile serves as a suitable model for studying biological selenium utilization.
• This research provides a genetic basis for understanding selenium cofactor insertion and its role in purine metabolism.