Bacteriophages: There's a Whole Army of Viruses That Have Genomes Unique to Their Own

Viruses depend on cells to replicate because they can not encode necessary enzymes for viral replication, according to BCcampus Open Publishing. Bacteriophages, viruses that infect bacteria, replicate in the cytoplasm since prokaryotic cells do not have a nucleus or organelles.

For eons, bacteriophages and bacteria have been at war wherein each side is evolving to more devilish tactics to infect or destroy the other. They are the epitome of the saying: "Nothing is constant in this world, except for change."

Eventually, bacteriophages evolved in a way that it took this arms race to a whole new level by changing its way of encoding their DNA.

Whole Army of Bacteriophages With Z-Genome

According to ScienceAlert, New research published in three separate papers has shown a whole army of bacteriophages having Z-genome, a non-standard DNA unique to the rest of the world.

Biologists Michael Grome and Farren Isaacs wrote in a recent Science editorial that accompanies their new research on bacteriophages that the genomic DNA is composed of nucleotides that form the genetic alphabet, ACTG, which is similar to all life forms.

But, in 1977, scientists have discovered that cyanophage S-2L has a DNA virus that the 'A' is substituted with 2-aminoadenine (Z) throughout its genome that forms the new genetic alphabet of ZTCG.

Scientists were fascinated by this discovery and found that no other bacteriophages have the Z-genome. Also, they have a hard time culturing the S-2L in the lab, setting aside the Z-genome as a curiosity.

How Z-Genome Works?

The science news website reported that the new research documented in three separate papers from researchers in China and France showed how the Z-genome is assembled and how it works.

Yan Zhou, from Tianjin University and the lead researcher from one of the studies, wrote in their paper that their work shows how nature has come up with increasing the diversity of genomes.

Zhou's team and microbiologist Dona Sleiman's team in the Institut Pasteur found that the base of the Z-genome is composed of two major proteins that they call PurZ and PurB.

Meanwhile, the third group of researchers from the Université Paris-Saclay led by biologist Valerie Pezo confirmed those findings and analyzed the DpoZ enzyme, which is responsible for assembling the Z-genome.

The three teams found a variety of bacteriophages that have Z-genomes by looking at sequence databases for the sequences related to the proteins and enzymes of the genome they were looking for.

New York University molecular biologist Jef Boeke, who was not part of the study, told The Scientist that the three teams did a remarkable comprehensive job of presenting the Z-genome, not as one crazy outlier but a whole army of bacteriophages that have a unique kind of DNA.

Zhou said that since the Z-base bacteriophages were discovered in a meteorite, their work could spark interest in the research about the origins of life and astrobiology. But until now, the Z-genome is still covered with many questions that are yet to be answered.

The three papers were all published in Science separately. Here are the titles and links of their papers:

D. Sleiman et al., "A third purine biosynthetic pathway encoded by aminoadenine-based viral DNA genomes."

V. Pezo et al., "Noncanonical DNA polymerization by aminoadenine-based siphoviruses."

Y. Zhou et al., "A widespread pathway for substitution of adenine by diaminopurine in phage genomes."

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