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In 1977, scientists showed that a virus called S-2L that infects cyanobacteria has no adenine in its genome. Instead, S-2L uses a nucleotide known as diaminopurine or 2-aminoadenine, shortened to Z, that makes three hydrogen bonds—rather than the two that adenine (A) makes—when paired with thymine (T). In three papers published today (April 29) in Science, researchers show that the use of Z by phages, those viruses that infect bacteria, is more widespread than previously believed, and they describe the pathways by which the alternative nucleotide is made and incorporated into phage genomes.
“It’s been known that there’s this phage that doesn’t have adenine in its genome . . . and it’s been an unsolved mystery about how it does that,” says Jef Boeke, a molecular biologist at New York University Grossman School of Medicine who was not involved in the work. These papers “spell that ...
