Bacteria Rewrite DNA

Most DNA is copied from DNA or RNA. A Science paper published April 16 reports that one bacterial enzyme can build part of a DNA sequence by using its own protein structure as the guide. (science.org) The work centers on DRT3, an anti-phage system found in bacteria. Pujuan Deng, Hyunbin Lee, Carlo Armijo, Haoqing Wang, and Alex Gao at Stanford reported that DRT3 contains two reverse transcriptases, called Drt3a and Drt3b, plus a noncoding RNA. (science.org) Reverse transcriptases usually copy a nucleic-acid template, the way a scribe copies text from a page. In DRT3, Drt3a still follows that rule, using an ACACAC sequence in the noncoding RNA to make a poly(GT) DNA strand. (science.org) The unusual step comes next. The paper says Drt3b makes the matching poly(AC) strand “in the complete absence of a nucleic acid template,” and cryo-electron microscopy at 2.6 angstrom resolution showed a 6:6:6 complex of Drt3a, Drt3b, and RNA. (science.org) That is why the study is getting attention beyond microbiology. The authors describe a “protein-templated mechanism for sequence-specific DNA synthesis,” which would add a third category to a field usually split between template-directed and template-independent polymerases. (science.org) The finding does not mean bacteria are freely rewriting their genomes at will. The reported product is a very specific alternating repeat, poly(GT/AC), and the system belongs to bacterial defenses against phages, the viruses that infect bacteria. (pubmed.ncbi.nlm.nih.gov) Researchers are also discussing a separate April 2026 paper on how to read RNA-protein structures inside living cells. In Molecular Cell, a Baylor College of Medicine-led team described msDMS-MaP, a one-step method for measuring RNA secondary and higher-order structures in cells. (cell.com) That second paper is a measurement advance, not the same discovery as DRT3. But it speaks to the same problem: RNA and proteins often work as mixed machines inside cells, and those structures can be hard to capture with standard methods. (cell.com) The long-COVID references in social posts come from an older line of research on infected human cells, not from the new bacterial DNA-synthesis paper. A Nature Microbiology study published March 23, 2023 found that SARS-CoV-2 infection restructured host chromatin architecture, including weaker A-compartment organization and more A-B mixing. (nature.com) That 2023 study examined human cells and a virus, while the 2026 Science paper examined a bacterial anti-phage enzyme. The overlap is conceptual: both stories involve proteins and RNA-linked machinery changing how genetic information is organized or processed, but they test different systems and answer different questions. (nature.com; science.org) The next step is not a headline but an experiment. Researchers will need to show how widespread protein-templated DNA synthesis is, what Drt3b’s DNA product does during phage attack, and whether related enzymes make more than one tightly constrained repeat. (science.org; pubmed.ncbi.nlm.nih.gov)