Bacteria write new genes
Bacterial defensive systems write new genes
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A newly described bacterial mechanism contradicts the traditional flow of genetic information—DNA, to RNA, and then proteins. Specifically, some bacteria can utilize an enzyme known as “reverse transcriptase” to convert RNA into DNA, creating entirely new genes.
One-Way Street Reversed
Traditionally, genetic information flows from DNA to RNA, and then to proteins, a sequence that forms the cornerstone of molecular biology. This concept was challenged in the 1970s by discovering viral reverse transcriptases that transcribe RNA into DNA, allowing some viruses to integrate into host genomes. However, the bacterial version uncovered by the recent study goes a step further. It doesn't just transcribe RNA into DNA; it uses this mechanism to create entirely new genes, a phenomenon previously unheard of in biological systems.
The Neo Gene and Its Implications
The bacterial reverse transcriptase was found in Klebsiella pneumoniae and is associated with a mysterious RNA sequence that, until now, had no known function. Researchers discovered that this RNA forms a hairpin-like structure, which the reverse transcriptase repeatedly reads, creating a DNA sequence of multiple identical segments. This repetitive sequence forms an open reading frame, termed "neo" for "never-ending open reading frame," due to its lack of a termination signal.
The Neo protein, produced in response to viral infection, halts cell division, providing a protective mechanism against viral takeover. The exact mechanism by which Neo achieves this, and the process by which viral infection triggers its production remain enigmatic, opening new avenues for research.
The discovery of this novel reverse transcription mechanism adds a new layer to our understanding of bacterial defense systems. CRISPR, the well-known gene-editing tool, is one of many strategies bacteria employ against viral attacks. The Neo system represents a more complex form of genetic defense, potentially offering new biotechnology and synthetic biology tools.
Future Directions and Implications
Bacteria that can create new genes through reverse transcription challenges existing dogmas and opens up numerous possibilities for future research. This mechanism could be harnessed for genetic engineering, offering novel approaches to gene therapy and synthetic biology. Furthermore, understanding how Neo proteins inhibit cell division could lead to new antiviral strategies or antibacterial treatments.
References:
https://www.nature.com/articles/d41586-024-01477-8
https://doi.org/10.1101/2024.05.08.593200