PhD candidates Heba Alattas (left) and Shirley Wong’s (right) study examining the Rex phenotype was highlighted by GENETICS, a top-tier research journal
Heba Alattas and Shirley Wong, both of the Slavcev lab, specialize in molecular genetics research and have conducted research examining and constructing bacteriophages, viruses that infect bacteria. Their recent study was featured on the cover of GENETICS, the journal by the Genetics Society of America, and explores how various phages interact with E. coli bacteria.
Their research built on examining how a phage called lambda infects E. coli cells:
“When lambda phages infect E. coli, we typically see that the E. coli bacteria aren’t killed immediately, and in fact live with the lambda phage inside the E. coli for several generations.” Alattas says. “Our study explored what happens when another bacteriophage – T4rll – comes along and tries to infect E. coli that’s already infected by lambda.”
This image is a whimsical depiction of T4rII infection. Two T4rII phages strategize on top of a map of the “E. coli oceans”, which shows a “Rex” ship they need to combat. Various gene names central to Rex can be seen on the map. Drawn and photographed by Shirley Wong and featuring figures 3D-printed by Jacob Ehrhardt.
The researchers studied a phenomenon called the Rex phenotype. The name describes the process where T4rll is unable to infect and kill an E. coli bacterium first infected by lambda. This unusual behaviour is the Rex phenotype. While it has been observed for some time, scientists do not yet understand why it occurs or what prevents T4rll from killing the E. coli cells.
“Previous studies examined lambda and T4rll to understand the Rex phenotype, but we decided to ask what role the E. coli cell itself plays in Rex,” Wong says. “We identified specific E. coli genes that are needed alongside lambda genes for the Rex phenotype to occur.”
While they have not yet completely explained the Rex phenotype, Alattas and Wong’s study represents a step towards understanding why the inability to infect occurs. By discovering key properties about phage exclusion mechanisms – about how, exactly, phages prevent and stop infections by other phages – Alattas and Wong’s study expands scientific understanding of the basic functioning of phages and bacteria hosts.
“Knowing how this and other exclusion systems work can hopefully lead to novel applications of the proteins involved, once their mechanisms are fully elucidated.” says Wong. “Additionally, this could help towards developing alternative strategies against antibiotic-resistant bacteria since we can build a better picture of how their predators affect it.”
Their work was recognized by the journal in part because the study helped revitalize interest in understanding the Rex phenotype.
“The last papers on Rex were published in the early 2000s,” says Alattas. “We’ve seen interest awaken after a long sleep. Down the road, when we have a fuller picture of how these exclusion mechanisms work, we can see useful applications of this knowledge in the design of antiviral medications and vaccines.”
Their study, “Identification of Escherichia coli Host Genes That Influence the Bacteriophage Lambda (λ) T4rII Exclusion (Rex) Phenotype”, was a December 2020 Highlight article in GENETICS.