ABOVE: © ISTOCK.COM, FPM
The paper
A. Millman et al., “Bacterial retrons function in anti-phage defense,” Cell, 183:1551–61.e12, 2020.
Many bacteria contain retrons, DNA sequences which code for enzymes that transcribe RNA into DNA and an unusual molecule made of both DNA and RNA. But microbiologists have puzzled over retrons’ function. “People suggested . . . this may be a selfish genetic element, [or] it may be involved in virulence,” says the Weizmann Institute of Science’s Rotem Sorek. “But nobody actually knew.”
Sorek and colleagues recently noticed that retrons often appear in the bacterial genome alongside genes involved in defense against bacteriophages. When the team cloned retrons into E. coli strains that normally lack these elements, those populations better resisted viral infection. The effect was due to the retron-equipped cells’ tendency to self-destruct if they became infected. “It sounds counterintuitive,” Sorek says—but it’s better for the colony to have a few ...
