Antimicrobial peptides are a broad group of molecules known to kill microbes such as bacteria, fungi and even viruses. However, there is a scientific bottleneck that confines research to a few naturally occurring classes of antimicrobial peptides. To overcome this limitation in new discoveries, a research team from University of Texas, Austin developed a high-throughput platform for screening thousands of synthetic peptides for antimicrobial activity.
"We thought, wouldn't it be great if a bacteria could synthesize the compound for us, because bacteria are cheap and easy to grow, and then test the compound on itself and report back and tell us, was that an antimicrobial or not,” said principal researcher Bryan Davies.”
Davies and his team then developed SLAY (Surface Localized Antimicrobial Display), a platform that allows screening of unlimited numbers of peptides of any length, composition, and structure in a single tube for activity. In SLAY, a peptide library is constructed. Each plasmid contains a different synthetic peptide and is then transformed into the bacteria of interest.
The expressed peptide (turned on by an inducer) comes out attached to an accompanying display system, which consists of a membrane anchor sequence and a tether that binds one end of the peptide. The tethered peptide can thus only interact with the outer surface of the bacterium that produced it.
Peptides with antimicrobial activity will inhibit cell growth and are depleted from the population. Next generation sequencing at the start and end of the experiment allows for the determination of the effective peptides from the plasmid sequences no longer present. By running hundreds of thousands of experiments simultaneously, SLAY can save a tremendous amount of space, time and cost.
According to the team’s early publication in Cell, SLAY enabled the screening of “~800,000 random peptide sequences for antimicrobial function and identified thousands of active sequences.” This has dramatically increased the number of known antimicrobial peptides, and now provides a new avenue of exploring beyond the limits of what nature has provided.
"So what if we have a thousand groups all using this system to follow their own interests and their own peptides?" said Davies. "Once you enable a community of that size, then I think you have a better chance of actually finding a new antibiotic that works."
Image: Graphical abstract of the SLAY platform. Generation of peptide libraries, high throughput assays and next gen sequencing enable the rapid screening of diverse synthetic sequences. Image courtesy of Bryan Davies and Elsevier Cell.