Antibiotic resistance is a global health threat. In 2019 alone, an estimated 1.3 million deaths were attributed to antibiotic resistant bacterial infections worldwide. Looking to contribute a solution to this growing problem, researchers at Baylor College of Medicine have been studying the process that drives antibiotic resistance at the molecular level.
They report in the journal Molecular Cell first steps that promote resistance to ciprofloxacin, or cipro for short, one of the most commonly prescribed antibiotics. The findings point at potential strategies that could prevent bacteria from developing resistance, extending the effectiveness of new and old antibiotics.
The Rosenberg lab’s discoveries of the steps involved in stress-induced mutagenesis revealed that two stress responses are essential: the general stress response and the DNA-damage response.
Some of the downstream steps of the process that leads to increased mutagenesis have been revealed previously by the Rosenberg lab and her colleagues. In this study, the researchers discovered the molecular mechanisms of the first steps between the antibiotic causing DNA breaks and the bacteria turning on the DNA damage response.
Instead, the first step consisted of disrupting the activity of a protein already present, RNA polymerase. RNA polymerase is key to protein synthesis. This enzyme binds to DNA and transcribes DNA-encoded instructions into an RNA sequence, which is then translated into a protein.
Rosenberg’s lab discovered that DNA repair can be an error-prone process. As repair of the broken DNA strands progresses, errors occur that alter the original DNA sequence producing mutations. Some of these mutations will confer bacteria resistance to cipro.
