Bacterial ‘barcode’ discovered by McMaster researchers in Hamilton

McMaster University researchers have discovered a new bacterial “barcode” used to differentiate beneficial and toxic molecules.

Biochemistry and Biomedical Sciences associate professor John Whitney and graduate students Prakhar Shah and Timothy Klein learned that disease-causing bacteria can “can figuratively scan genetic codes to learn which proteins to keep and which proteins to expel into the environment,” according to a McMaster article by Blake Dillon. 

The research was recently published in the journal Proceedings of the National Academy of Sciences (PNAS). It outlines how the expelled proteins are often harmful to human cells. As a result identifying these proteins is essential to the bacteria’s ability to spread illness through the body.

“Proteins are one of the fundamental building blocks of life,” Whitney explained to Dillon, “They quite literally allow bacterial pathogens to do everything that they do. And while the vast majority of proteins remain inside bacteria to carry out functions like metabolism, there is a very small subset that act outside of the organism — like toxins.”

The team wanted to find out how three different proteins came from the same bacterial system, “There were no known similarities between the toxins — they don’t look anything alike, and they don’t do anything similar,” Whitney explained, “Our rationale was, for them to all pass through the same protein secretion machine, there must be something common between them.”

Whitney was correct. “Each toxin shared a “domain,” which Whitney colloquially compares to a barcode. He says that while the barcode was shared by all three toxins under study, it was absent from the other three-thousand-or-so proteins in the bacteria, indicating that it serves as the export signal,” Dillon wrote.

“A lot of pathogens use this system,” Shah told Dillon, “Therefore, our discovery has important implications on our understanding of the virulence strategies used by a wide range of human pathogens.”