Release date: 2018-01-30
For billions of years, bacteria have used complex defense systems to protect themselves from phage invasion. By analyzing these immune mechanisms, humans have developed powerful molecular biology tools, such as the familiar restriction enzymes, CRISPR/Cas9. However, this is just the "tip of the iceberg."
On January 15th, a recent article in the journal Science revealed that scientists have discovered more than 10 immune mechanisms in bacteria, more than twice the known immune defense system.
Image source: Journal (DOI: 10.1126/science.aar4120)
Latest discovery
Molecular geneticist Rotem Sorek from the Weizmann Institute in Israel led the team to try to fully understand the bacterial immune defense system. They analyzed about 45,000 genomes from bacteria and archaea and studied gene clusters near the defense islands (proven defense genes).
The researchers constructed a corresponding bacterial model for these promising candidate genes, and then used a large number of phage to detect the defense functions of these genes.
Of the 26 antiphage systems they tested, 9 were confirmed to be involved in the antiviral mechanism, and 1 was associated with a defense plasmid. The Rotem Sorek team named these systems with the mythical protector, such as Druantia, Kiwa, etc.
Although the other 16 systems did not escape the pathogen invasion well in the trial, they are still likely to be effective defense systems. "These systems may require additional coding genes, or elements such as related promoters may not work properly in bacterial models," the researchers explained.
Some clues
At a macro level, the Rotem Sorek team did not find specific mechanisms by which these immune systems protect bacteria from bacteriophage invasion, but they found some clues about how they work:
1) The "Theoris" system (named after the Egyptian patronage responsible for childbirth and fertility) contains a TLR receptor region that regulates the interaction of intracellular signaling proteins, which was previously confirmed to be involved in the regulation of RNA interference (RNAi) by the prokaryotic Argonaute Genes are related.
2) The "Zorya" system was found to contain a constituent element of a proton channel. "We have initially confirmed that once the bacteria are infected, the proton channel may 'suicide', which causes the cell membrane to depolarize," Sorek said.
Significance
Researchers believe that once the mechanism of immune defense is understood, the key molecules/proteins will be used by molecular biology to help the development of life medicine. It is necessary to know that the popular "magic shear" technology CRISPR is originally a set of bacteria. The natural immune system, in addition, many nucleic acid tool enzymes are also derived from microorganisms.
Sorek believes: "As long as you find a complex immune system and finally resolve its mechanism, it is expected to be developed into a very effective tool."
“From a scientific point of view, this research is cool.†Rodolphe Barrangou, a research Fellow at North Carolina State University, commented, “It is clear that with the deepening of the immune mechanism, we will harvest molecular tools with powerful potential. The more alternatives to CRISPR, the better."
Reference materials:
Researchers Discover 10 New Immune Systems in Bacteria
Source: Bio-Exploration
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