All known life uses the same four-letter genetic alphabet. Researchers at the University of California San Diego have now shown that one of life's essential enzymes can also read and copy a version with eight letters.
The team studied RNA polymerase, the enzyme that reads DNA and makes RNA. Using biochemical experiments and high-resolution cryo-electron microscopy, the researchers watched it recognize two synthetic DNA base pairs.
The images showed that the enzyme recognized the new letters using the same kinds of structural signals it uses for natural DNA. That helps explain how expanded genetic information could be copied accurately.
The work is an early step toward building biological systems with more genetic information. Such systems could one day help researchers design useful medicines or other materials, although more research is needed.
