Home https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Science https://server7.kproxy.com/servlet/redirect.srv/sruj/smyrwpoii/p2/ Some viruses have a completely different genome from the rest of life on Earth

Some viruses have a completely different genome from the rest of life on Earth



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,”

; write biologists Michael Groom and Farron Isaacs recently. Science edition accompanying the new study of the genetics of bacteriophages.

“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 Рwhich 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.


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