New DNA production report
- Scientists published reports describing a fundamentally new way that life can produce DNA, surprising many researchers. (x.com) - The coverage emphasizes that the mechanism differs from known biological pathways and has captured scientific attention. (x.com) - Authors and commentators say the finding could open major lines of inquiry in molecular biology and synthetic systems. (x.com)(x.com)
Scientists reported on April 17 that some bacteria can make a defined DNA sequence partly without copying it from DNA or RNA, using a protein-guided step instead. (science.org) The study, published in *Science* by Pujuan Deng, Hyunbin Lee, Carlo Armijo, Haoqing Wang and Alex Gao at Stanford University, describes an anti-phage system called DRT3. DRT3 contains two reverse transcriptases, named Drt3a and Drt3b, plus one noncoding RNA. (science.org) DNA polymerases usually work like copyists: they read an existing strand and add matching letters one by one. The *Science* paper says Drt3a follows that rule for one strand, making poly(GT) from an ACACAC sequence in the RNA, while Drt3b makes the matching poly(AC) strand without any nucleic-acid template at its active site. (science.org) The Stanford team used cryo-electron microscopy at 2.6 angstrom resolution and reported a D3-symmetric 6:6:6 complex of Drt3a, Drt3b and the RNA. They said conserved amino-acid residues in Drt3b, rather than base-pairing to a guide strand, enforce the alternating pattern of the second DNA strand. (science.org) That finding lands in a field that had already been shifting. A 2025 *Nature* paper from Samuel Sternberg’s group reported that another bacterial defense-associated reverse transcriptase, DRT9, makes long poly-deoxyadenylate chains during phage infection, with a noncoding RNA acting as scaffold and template and protein residues probably priming DNA synthesis. (nature.com) An earlier 2024 *Science* study, highlighted by *Nature Reviews Genetics*, showed that a related system called DRT2 uses a noncoding RNA template to assemble a new repetitive gene during phage defense. That placed bacterial reverse transcriptases outside the standard textbook role of copying RNA into DNA and into a broader set of DNA-making defense reactions. (nature.com) The new paper narrows the claim. It does not say cells generally replicate chromosomes without templates; it says one bacterial antiviral system can generate an alternating repeat, poly(GT/AC), through a mixed mechanism in which one strand is RNA-templated and the other is protein-templated. (science.org) The immediate biological setting is phage defense, the arms race between bacteria and the viruses that infect them. Defense-associated reverse transcriptases are widespread in bacteria, and both the 2025 *Nature* paper and the 2026 *Science* paper describe them as a source of unconventional DNA-synthesis chemistry. (nature.com) (science.org) The practical appeal is that molecular biologists have long searched for enzymes that can write DNA in new ways, not just copy it. The authors said DRT3 expands the known range of nucleic-acid polymerases, and recent reviews and technology reports have framed new DNA-writing methods as a bottleneck for synthetic biology and genome engineering. (science.org) (nature.com) What happens next is likely to be less about rewriting the central dogma than mapping how many of these odd enzymes exist and what they make. For now, the clearest result is narrower and concrete: a bacterial anti-phage complex can produce sequence-specific DNA with a protein-guided step that standard biology texts did not include. (science.org)
