Bacteria Read Eight DNA Letters. Life Runs on Only Four.

Every known living thing spells its genes with four letters. A bacterial enzyme read eight, and it treated the four new ones much like the old.

The enzyme is RNA polymerase, the molecular machine that copies DNA's instructions into RNA, the opening move in switching a gene on. A team at the University of California San Diego, led by Dong Wang, studied the version found in E. coli bacteria. Using cryo-electron microscopy, a high-resolution imaging method, they watched it identify and use two pairs of lab-made letters that no organism makes on its own. Together with the natural letters, those form an eight-letter system called hachimoji. The results came out in the journal Nature Communications.

The images showed the enzyme spotting the artificial letters with a lot of the same cues it uses for natural ones. That may be why it copies the larger alphabet accurately. A companion paper in PNAS from the same lab found it also recognizes a different synthetic pair that has no hydrogen bonds, the links that usually keep natural pairs glued together.

Earlier work with expanded alphabets produced synthetic DNA that can spot liver cancer cells. Possible uses include new diagnostics, treatments and engineered systems with abilities nature never supplied.

Cryo-electron microscopy sees detail finer than one atom, and it caught a bacterium's enzyme shaking hands with four letters from a lab.

Read the full story at ScienceDaily, September 5, 2026

Hot Take: A bacterial enzyme reads eight letters without blinking. Meanwhile we're all skimming past the second line of every post.