Microbes Break Genetic Code Quite Often, Study Finds [Video]

A new study by researchers at the U.S. Department of Energy Joint Genome Institute (DOE JGI) shows that several types of bacteria break the canonical genetic code.

Scientists, earlier, believed that almost all microbes follow the canonical genetic code - a kind of shared universal vocabulary - to produce proteins. The research challenges a central idea in genetics and could help researchers build synthetic lifeforms.

"All along, we presumed that the code or vocabulary used by organisms was universal, applying to all branches of the tree of life, with vanishingly few exceptions," said DOE JGI Director Eddy Rubin, who is also the senior author of the study, according to a news release. "We have now confirmed that this just isn't so. There is a significant portion of life that uses different vocabularies where the same word means different things in different organisms."

Previously, research had shown that certain types of bacteria don't follow the genetic code. This is the first time that researchers have found that code-breaking is more rampant that previously assumed.

Breaking the Code

A central dogma in molecular biology is that DNA acts as a template or a blueprint for protein synthesis. The nucleotides on the DNA are arranged in triplets - "codons". Totally, there are 64 codons, of which three act as a stop signal. These "nonsense" codons: Amber, Opal and Ochre tell the organism to stop making a particular protein.

The new study finds that not all organisms accept Amber, Opal and Ochre as stop signals and in fact, use them to keep building the protein.

Microbial Dark World

Most research in microbiology concerns itself with microbes that are already known. According to researchers at JGI, 99 percent of the microbial world is still a mystery to science. Scientists usually study bacteria that follow the genetic code.

The current study is part of a larger project that is looking into the "wild" to find the rule-breaking bacteria. Researchers sifted through 5.6 trillion letters of genetic code. The data came from samples taken from 1,700 areas on the earth, including 17 from the human body.

Researchers went hunting for "Opal-recoded" organisms, which interpret the stop codon - "Opal" - to keep adding amino acid to the protein.

"We were surprised to find that an unprecedented number of bacteria in the wild possess these codon reassignments, from "stop" to amino-acid encoding "sense," up to 10 percent of the time in some environments," said Rubin in a news release.

What's more is that it wasn't just the bacteria that were breaking the code, but also certain viruses called as phages that were using "stop" codes to make proteins.

The research could help design artificial bacteria and strengthen bio-security, Nature reported.

The study is published in the journal Science.

See a video of Rubin talking about the research below: