Antimicrobial peptides are a distinctive class of potent, broad-spectrum antibiotics produced by the body's innate immune system -- the first line of defense against disease-causing microbes. In a new study, Yixin Shi, Ph.D., and Wei Kong, Ph.D., researchers in the Center for Infectious Diseases and Vaccinology at Arizona State University's Biodesign Institute, explore the clever techniques used by bacteria to survive destruction from antimicrobial peptides -- potent defense factors produced by all living forms, including humans.

Professor Shi underscores the importance of antimicrobial peptides in the pitched battle against multi-drug resistant bacteria:

"All bacteria treated with conventional antibiotics will develop antibiotic resistance," he says. "But antimicrobial peptides have a unique function. Many of them target the bacterial membrane, making it very difficult for bacteria to develop resistance." After fusing with the invasive bacteria's membrane, antimicrobial peptides cause membrane leakage, leading to cell destruction or lysis.

The researchers describe one strategy bacteria have evolved to try to shield themselves from the effects of antimicrobial peptides, allowing the pathogens to survive efforts to eradicate them. A two-component system, used by pathogenic invaders like E coli and Salmonella, facilitates expression of multi-drug pumps that can remove antimicrobial peptides from the bacterium's cytoplasm.

The study's findings suggest that if this two-component system could be disabled, disease-causing bacteria would fall victim to the lethal effects of antimicrobial peptides. The research helps open the door to the clinical application of these powerful antibiotics at a time when such novel therapeutics are desperately needed to stem the tide of bacterial resistance.

Scientific collaborators from ASU's School of Life Sciences as well as researchers from the College of Life Sciences, Inner Mongolia University, China and the State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, China join Drs. Shi and Kong.

The group's research results recently appeared in the Journal of Biological Chemistry.