This seems interesting - re: RNA World and OOL

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The title of the news piece is provocative, and the paper itself has the potential to challenge a lot of what we think we know about the OOL and the RNA World. Enjoy!

https://www.science.org/content/article/scientists-stunned-fundamentally-new-way-life-produces-dna

The Abstract:

Defense-associated reverse transcriptases (DRTs) are widespread bacterial anti-phage systems that use unconventional mechanisms of polynucleotide synthesis. We show that DRT3, which comprises two distinct RTs (Drt3a and Drt3b) and a noncoding RNA (ncRNA), synthesizes alternating poly(GT/AC) double-stranded DNA. Cryo–electron microscopy structures at 2.6 Å resolution reveal a D3-symmetric 6:6:6 complex of Drt3a, Drt3b, and ncRNA. Drt3a produces the poly(GT) strand using a conserved ACACAC template within the ncRNA. Notably, Drt3b synthesizes a complementary, protein-primed poly(AC) strand in the complete absence of a nucleic acid template, using conserved active site residues specific to Drt3b to enforce precise base alternation. These findings expand the functional landscape of nucleic acid polymerases, revealing a protein-templated mechanism for sequence-specific DNA synthesis.

We’ve known for awhile that proteins can mimic structural features in RNA. This study takes the concept in new directions that are at the very least thought-provoking.

The paper:

https://www.science.org/doi/10.1126/science.aed1656

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Very interesting. Not sure I understand what they mean. Are the amino acids in the active site of Drt3b functioning as a sort of “template” for the repeating AC single-stranded DNA? This is the sort of thing I think needs a drawing/picture to clarify.

Edit: Ah yes that is what they are saying in the news article. Active site amino acids are quite literally functioning as a template for the DNA strand.

This is very close to a kind of simple reverse self-translation.