A newly published study reveals that the opportunistic bacterium Pseudomonas aeruginosa leverages vitamin C to neutralize a key component of the human immune response, enhancing its ability to cause severe infections. Researchers from the University of São Paulo and the University of Massachusetts Chan Medical School have uncovered the molecular mechanism by which this pathogen defends itself against oxidative stress, a critical part of how the body fights off invaders.
How Pseudomonas aeruginosa Defends Itself
Pseudomonas aeruginosa is a particularly dangerous bacterium because it thrives in compromised immune systems, causing infections like pneumonia in cystic fibrosis patients, urinary tract infections, and severe wound infections. Its resistance to antibiotics makes it a priority target for new treatments, according to the World Health Organization.
When the body detects an infection, immune cells release reactive oxygen species – essentially, controlled bursts of damaging chemicals – to kill the invading bacteria. However, P. aeruginosa possesses sophisticated defenses to counteract this attack, including an enzyme called LsfA, a member of the peroxiredoxin (Prx6) family.
Vitamin C as an Unexpected Ally
The study, published in Redox Biology, details how LsfA utilizes vitamin C (ascorbate) to detoxify hydrogen peroxide, a potent oxidant released by immune cells. This interaction allows the bacterium to resist the body’s oxidative attack, bolstering its virulence.
“We demonstrated that ascorbate can act as a reducing agent in a cellular system, which is something new,” explains Rogério Luis Aleixo-Silva, a researcher involved in the study. The team also obtained the first structural characterization of a bacterial Prx6 enzyme, revealing how vitamin C directly interacts with LsfA’s active site to regenerate its antioxidant function.
Implications for New Antibacterial Therapies
The discovery challenges the conventional understanding of how these enzymes work, suggesting that vitamin C plays a more significant role in bacterial defense than previously thought. Importantly, the bacterial LsfA enzyme differs structurally from its human counterpart, offering a potential target for new drugs. Researchers have already begun using computational modeling to identify compounds that could disrupt the enzyme’s function without harming human cells.
The next steps involve further investigation into how P. aeruginosa metabolizes vitamin C, as well as testing the effects of blocking LsfA in realistic infection models. This research could lead to the development of novel antibacterial strategies that exploit the bacterium’s own defenses against it, offering a new weapon in the fight against antibiotic-resistant infections
