March 23, 2023

E. coli uses serine to abide acidity

Vanderbilt researchers have discovered another acid resistance mechanism for UTI-causing E. coli, laying the foundation for targeted antibacterial therapies.

E. coli bacteria are the main cause of urinary tract infections. It is thought that we acquire many of the E. coli strains through ingestion, which means that these bacteria must survive the harsh conditions in the stomach, which is acidic enough to dissolve skin. How do these bacteria survive acidic conditions that should destroy them?

Bacteria survive by using amino acids, the building blocks of proteins, to neutralize acids. Maria Hadjifrangiskou, PhD, and colleagues published a study showing that E. coli uses the amino acid serine, in addition to other amino acids, to survive acidic conditions.

When E. coli is cultured in an acidic solution, the bacteria internalize serine and activate a stimulus response system. This system processes serine into ammonia, a strong base that neutralizes acids. Inactivating this system in E. coli hindered bacterial growth, implying that this serine-processing system is necessary for E. coli survival in acidic conditions.

This study, which is published in mBio, adds one more acid resistance mechanism (AR6) to the arsenal of E. coli survival strategies, increases understanding of E. coli survival, and lays the foundation for targeted antibacterial therapies. 

Other authors of the study include first author Michelle Wiebe, John Brannon, PhD, Bradley Steiner, Adebisi  Bamidele, Alexandra Schrimpe-Rutledge, PhD, Simona Codreanu, PhD, Stacy Sherrod, PhD, and John McLean, PhD.

This work was supported by the National Institutes of Health (grants DK123967, AI168468, GM007569, AI112541) and in part using the resources of the Center for Innovative Technology at Vanderbilt University.