A magazine for friends of the Warren Alpert Medical School of Brown University.

Coping Mechanisms


Understanding how bacteria regulate stress could aid the development of antimicrobials.

Scientists have captured the first “snapshot” of two proteins involved in delivering a bacterial stress-response master regulator to the cell’s recycling machinery.

The Brown University-led team found that RssB—a protein that specifically recognizes the master regulator and delivers it to the recycling machinery somewhat like a recycling truck—forms a compact structure with a factor that inhibits RssB activity. The inhibition factor, called IraD, is triggered by DNA damage, one of many stresses the master regulator helps bacteria survive by turning on important genes.

The stress-response master regulator is critical for many bacteria—including those that cause human disease such as E. coli and Salmonella—to survive nutrient deprivation and other stressful situations such as those encountered during the process of infecting a new host.

It is also important for the development and growth of biofilms, which are often resistant to antibiotics and grow on medical devices such as catheters and artificial heart valves.

“Before this study, people didn’t really understand how IraD acts to inhibit RssB,” says Alexandra Deaconescu, PhD, an assistant professor of molecular biology, cell biology, and biochemistry and corresponding author for the study. “We were able to determine the structure of IraD bound to RssB and figure out how it works. Understanding how bacteria control the amount of stress-response master regulator could lead to the development of antimicrobials or even agents to halt the evolution of antibiotic resistance.”

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