Z is for…

Photo by CDC on Unsplash

…2-aminoadenine, and if you happen to be a bacteriophage it’s quite important.

Very important, in fact. And it might be important to our understanding of, well, how life even works.

DNA Bases

Most life on Earth has DNA (the exception is some viruses, which use RNA instead. SARS-CoV-2 is an RNA virus.).

And DNA contains four bases. Adenine, cytosine, guanine, and thymine. All DNA has these four bases, and they bond together in specific ways. Those specific ways make up the genome, the biological code that makes us us.

Until they don’t.

In 1977, researchers discovered that a bacteriophage (a kind of virus that infects bacteria) called cyanophage S-2L was…well…interesting. Instead of adenine, it had 2-aminoadenine (or 2,6-diaminopurine, I’m seeing both). They added this to the DNA alphabet as Z, but the virus was hard to culture. They thought this was some one off weirdness that had no doubt evolved as host evasion. Bacteria mutate quickly, so phages have to keep up, and it was unsurprising something really weird would happen.

Photo by Alexander Popov on Unsplash

S-2L Is Not Alone