In the world of microbial warfare, sometimes you have to change the very fabric of who you are.
The viruses that infect bacteria – aptly called bacteriophages – and their prey have been at war for centuries, with each country developing more devilish tactics to infect or destroy them. Eventually, some bacteriophages took this arms race to a new level by changing the way they encode their DNA.
At least that’s how we think it happened. Once considered extraordinary, a new study published in three separate articles shows that there is a whole army of bacteriophages with non-standard DNA, which researchers call the Z-genome.
“Genomic DNA consists of four standard nucleotides … These nucleobases form the genetic alphabet ATCG, which is preserved in all areas of life,”
“However, in 1977, the cyanophage S-2L DNA virus was detected in all cases of” A “replaced by 2-aminoadenine (Z) throughout its genome, forming the genetic alphabet ZTCG.”
The reason seems to have been self-defense. Within the connecting “steps” of the double helix of DNA, the base “Z” forms a triple bond with the opposite base “T”, one more than the two bonds of the regular bond A: T. This makes the viral genome harder and more difficult for bacteria to be distributed with chemicals called nucleases.
Although scientists were fascinated, no other bacteriophages with the Z-genome were found, and with the difficulty of culturing S-2L in the laboratory, the Z-genome was set aside as a curiosity.
Now, research documented in three separate studies by researchers from France and China shows that this is not a one-off, while characterizing how the Z-genome works and how it is assembled.
“Scientists have long dreamed of diversifying the basics. Our work shows that nature has already figured out a way to do this,” wrote one of the teams, led by first author Yang Zhou of Tianjin University, in a report.
Zhou’s team, along with another group led by the Microbiologist at the Pasteur Institute, Donna Sleiman, discovered two major proteins they called PurZ and PurB; they form the basis of the “Z”.
A third group, led by Université Paris-Saclay synthetic biologist Valerie Pezzo, confirmed these findings and analyzed an enzyme called DpoZ – which is responsible for putting the entire Z-genome together.
All three searched genetic sequence databases for the sequences associated with their proteins and enzymes, and found a wide variety of bacteriophages with similar genes.
“[The authors] have done an amazingly comprehensive job to show that this is not a crazy apostate, but there is a whole group of bacteriophages that have this kind of genetic material, “said Jeff Boke, a molecular biologist at New York University who was not involved. The scientist.
There are still many questions to answer about the Z-genome.
For example, is the Z genome compatible with ordinary cellular machines like ours? And could it be used in the same way that artificial DNA begins to be?
“Base Z has been unequivocally identified in a carbon meteorite and has been proposed as a nucleobase that could be made available to the origin of life,” the team led by Zhou wrote in its report.
“Given that base Z was discovered in a meteorite, our work may arouse interest in interdisciplinary research on the origin of life and astrobiology.”
The three articles are published in Science here, here and here.