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Researchers at the University of California San Diego showed that Escherichia coli RNA polymerase can read and transcribe a synthetic eight-letter genetic alphabet, in a study published in Nature Communications on 2 September 2026.
The system, called hachimoji DNA, adds four synthetic bases - P, Z, B and S - to the four natural ones, A, T, C and G.
The bacterial enzyme recognised the synthetic base pairs using biochemical signals similar to those it uses for natural bases, with the P-Z pair transcribed about twice as slowly as a natural G-C pair.
The team used high-resolution cryo-electron microscopy to capture structural snapshots of the enzyme working on the synthetic bases.
The experiments were done in vitro on synthetic DNA templates - no living eight-letter organism was created.
In the central dogma, DNA is transcribed into RNA and RNA is translated into protein. RNA polymerase is the enzyme that does the first step, reading a DNA template and building a matching RNA strand base by base.
Simple Analogy: A copyist reading one script and writing out a working copy in a second alphabet.
DNA to RNA to protein. This study concerns the first arrow, transcription; translation of an eight-letter message into protein is a separate, unsolved problem.
The technique used here won the 2017 Nobel Prize in Chemistry for Jacques Dubochet, Joachim Frank and Richard Henderson, and has become the standard tool for imaging large biomolecules.
An expanded genetic alphabet that works with natural enzymes is evidence that life's four-letter code is one workable option rather than the only one - a standard argument in discussions of alternative biochemistries.
GS Paper III > Science and Technology: biotechnology, synthetic biology
General Science > Biology: DNA, RNA, enzymes
With reference to the recent developments in science, which one of the following statements is not correct?
Answer: Functional chromosomes can be created by joining segments of DNA taken from cells of different species.
What is the application of Somatic Cell Nuclear Transfer Technology?
Answer: Reproductive cloning of animals
A synthetic genetic system of eight letters - the four natural bases plus P, Z, B and S - first reported in 2019.
The enzyme that synthesises RNA from a DNA template during transcription; present in both prokaryotes and eukaryotes.
A structural biology technique that images flash-frozen biomolecules at near-atomic resolution.