Microbial warfare around the world, sometimes you need to alter the very fabric of who you are. The Viruses that infect bacteria are called Bacteriophages and Their victims have been at war for aeon, each side evolving more demonic tactics to destroy themselves. Finally, some Bacteriophages have taken this arms race to a new level by changing their way of coding their DNA.
At least, that's the way we feel. Once considered an aberration, new research published in three separate papers shows that there is an entire army of Bacteriophages with nonstandard DNA, which researchers call a Z genome.
"Genomic DNA is comprised of four nucleotides also called nucleobases, These nucleobases form the genetic alphabet, ATGC, which is conserved across all domains of life," biologists Michael Grome and Farren Isaacs have written in a recent scientific editorial supporting new research on bacteriophage genetics.
"Nevertheless, in 1977, the cyanophagous DNA virus S-2L was discovered with all the cases of 'A' substituted for 2-aminoadenin (Z) in its entire genome forming the genetic alphabet ZTCG."
The reason seemed to be self-defense. In the 'rungs' of a double DNA helix bond, the base 'Z' forms a triple bond at the opposite base 'T', one more than the two bonds of the regular A:T connection. This makes the viral genome more resistant and harder for bacteria to separate from the chemicals known as nucleases.
In spite of the fact that the scientists were hypnotized, no other bacteriophage was found with the Z genome, and with the difficulty to grow S-2L in a laboratory, the Z genome was set aside as a curiosity.
At present, The documented research works in three separate studies from researchers in France and China shows that it was not an isolated case, while characterizing the functioning of the Z genome and its assembly.
"The long dream of Scientists of increasing the diversity bases. Our work shows that nature has already come up with a way to do that," one of the teams, led by first author Yan Zhou from Tianjin University, wrote in their paper.
Zhou's team, together with another group led by institute Pasteur microbiologist Dona Sleiman, discovered two basic proteins called PurZ and PurB, which make up the Z base.
A third group, led by synthetic biologist from Paris-Saclay University Valerie Pezo, corroborated these findings and analysed an enzyme, called DpoZ, which is responsible for assembling the entire Z genome.
The three researchers searched the gene sequence databases for the sequences associated with their proteins and enzymes, and found a large variety of Bacteriophage with similar genes.
"[The authors] have made a wonderfully comprehensive effort of showing that this is not one crazy outlier, but there's a entire group of Bacteriophages that have this kind of genetic material," Jef Boeke, a molecular biologist at New York University who was not involved in the work, told The Scientist.
There are still a few questions to answer regarding the Z-genome.
Is a Z-genome, for example, compatible with normal cell machinery like ours? May it be used in the same way as synthetic DNA is being used?
In their article, the team led by Zhou wrote, "The Z base has been unambiguously detected in a carbonaceous meteorite and suggested as a nucleobase that may have been available for the origin of life."
"Since the Z foundation was discovered in a meteorite, our findings may pique interest in interdisciplinary research on life's origins and astrobiology."
This is so cool! I actually find it really interesting though that, even though this life form was found on a foreign meteorite, it still shares similar DNA at all!