Researchers discover protein DNA method

Stanford University researchers reported in April that they had identified a bacterial defense system that makes DNA in two different ways, including one that uses a protein’s own structure as the template. The work appeared in *Science* as social posts on May 15 recirculated the finding with claims that it “updates textbooks.” The paper itself describes the mechanism more narrowly: a bacterial anti-phage system called DRT3 synthesizes a repetitive double-stranded DNA product, with one strand made from an RNA template and the other made without any nucleic-acid template. The authors said that second step reveals a protein-templated mechanism for sequence-specific DNA synthesis. ### What exactly did the researchers find? The *Science* paper by Pujuan Deng, Hyunbin Lee, Carlo Armijo, Haoqing Wang and Alex Gao said DRT3 is made of two reverse transcriptases, Drt3a and Drt3b, plus a noncoding RNA. In experiments described in the paper, the system produced alternating poly(GT/AC) double-stranded DNA. The paper said Drt3a makes the poly(GT) strand by copying a conserved ACACAC sequence embedded in the noncoding RNA. (science.org) Drt3b, by contrast, makes the complementary poly(AC) strand “in the complete absence of a nucleic acid template,” according to the paper’s abstract. ### How can a protein act as a template for DNA? Alex Gao, the Stanford biochemist who was the paper’s corresponding author, told *Science* that “the protein itself serves as the blueprint for the DNA sequence.” The paper said conserved residues in Drt3b’s active site enforce the alternating pattern during synthesis, which is why outside summaries described the enzyme’s shape or amino acids as the guide. (science.org) The authors did not report that bacteria broadly abandoned ordinary DNA copying. The finding concerns one enzyme in one defense system making a specific repetitive strand, not a replacement for standard DNA replication across life. The paper said the result “expand[s] the functional landscape of nucleic acid polymerases,” while Gao told *Science* it was “a fundamentally new way that life produces DNA.” (t.co) ### Does this overturn the central dogma? The April 16 *Science* news article framed the work as challenging long-held assumptions about how DNA is made, and some secondary coverage said it challenged the central dogma. But the research paper itself is more specific: it reports a protein-templated route for sequence-specific DNA synthesis inside a bacterial anti-phage system. The underlying result does not erase the standard flow in which DNA is copied from nucleic acid templates in replication and transcribed into RNA for protein production. (science.org) Instead, the paper adds an exception to the known catalog of polymerase behaviors, alongside other unusual defense-associated reverse transcriptases cited by the authors. ### How widespread is this system in bacteria? (t.co) The supplementary materials said the team identified 2,269 intact DRT3 systems after manual curation of sequence data. To reduce redundancy, the researchers grouped Drt3b sequences into 1,232 clusters. Phys.org’s summary of the study said the researchers found DRT3 in at least 20 bacterial species, where Drt3a and Drt3b usually appeared together. (science.org) That report also said the team moved the system into *E. coli* and challenged the bacteria with phages to test the defense mechanism. ### What is still unknown? Richard Stone reported in *Science* that Gao said the team was still not sure exactly how DRT3 protects bacteria from phages. (science.org) Secondary coverage citing Gao said one possibility is that the unusual DNA product could bind phage components or help other immune elements detect infection, but that remains a proposed mechanism rather than a demonstrated one in the paper. (phys.org) The April 2026 paper leaves the next step with the mechanism of defense and with the broader search for related systems. The supplementary materials show the authors had already cataloged thousands of DRT3 systems, and the published report in *Science* remains the primary source for following that work by Deng, Lee, Armijo, Wang and Gao. (science.org) (t.co)