Unusual Life Form Uses 'Back Door' to Replicate: Implications for Cancer Spread

Life isn't as straightforward as you might expect. Scientists have discovered that a rudimentary form of life that is found in some of the harshest environments on Earth is able to sidestep normal replication processes and reproduce by the "back door." The findings could have implications for life on other planets in addition to how life first formed on our own planet.

The life form in this particular study is called Haloferax volcanii. This organism is part of a family of single-celled organisms called archaea that until recently were thought to be a type of bacteria.  Archaea were originally discovered in extreme environments and can survive at very high or very low temperatures, or in highly salty, acidic or alkaline water. They form one of three distinct branches of life along with bacteria and eukaryotes, which are multi-celled organisms that include humans and other animals. At a genetic level, archaea have been found to be more closely related to eukaryotes.

"Although they look like bacteria and behave like bacteria, archaea are actually more closely related to us," said Thorsten Allers, one of the researchers, in a news release. "Where we really see the similarities is when we look at the enzymes that are responsible for DNA replication and that's why we thought this would be an interesting system to work on. We've got something that's life but not as we know it: on the outside, they look like bacteria but on the inside they look like us."

In order to reproduce, all life forms need to copy their DNA before the cell can divide. They do this via a series of "replication origins" that are located around their chromosomes. Proteins bind at these locations in order to start the replication process.

In this study, though, the researchers found that the Haloferax volcanii is able to spontaneously begin a chain reaction of replication all around its chromosomes even when replication origins have been eliminated. In addition, the scientists found that this archaea without chromosomal origins actually grew faster.

"The way cells initiates this replication process is to use a form of DNA repair that exists in all of us, but they just hijack this process for a different purpose," said Conrad Nieduszynski, one of the researchers in a news release. "By using this mechanism, they kick-start replication at multiple sites around the chromosome at the same time."

Since origins are unnecessary in Haloferax volcanii, it's very possible that researchers have uncovered an example of a "selfish gene"--something that benefits the origins by offering the chance to be continually replicated while offering no advantage to the organism itself. More specifically, understanding this process could help better understand how cancer cells replicate.

"Scientists think that cancer cells revert back to a more primitive state without these forms of control," said Allers. "This is how they resemble Haloferax volcanii."

The findings are published in the journal Nature.