BACTERIA USE NOVEL MECHANISM TO EXPRESS GENES, STUDY FINDS
COLUMBUS, Ohio – New research on how bacteria make compounds critical to their survival may help scientists create antibiotics for controlling dangerous bacterial pathogens.
For decades scientists believed that gene regulation in bacteria depended solely on regulatory proteins. But new findings have altered those beliefs. In the current study, the researchers found that bacteria use RNA to directly measure a signal and to control the related genes, rather than using a messenger protein to shuttle information to the gene.
Henkin and her colleagues looked at how Bacillus subtilis, a harmless bacteria, makes the amino acid lysine. Lysine is a crucial ingredient in making protein and in building bacterial cell walls.
Although B. subtilis is innocuous, it's a cousin of Bacillus anthracis, the pathogen that causes anthrax.
"Figuring out how pathogens control their genes could help in developing antibiotics for some of medicine's worst enemies," Henkin said. "We are quickly running out of effective antibiotics, as the bacteria develop resistance to the ones we have.
"The strain of anthrax that's been in the news is sensitive to antibiotics, but there are antibiotic-resistant strains," she continued. "Also, antibiotic-resistant Staphylococcus infections are a serious problem, particularly in hospitalized patients. A staph infection can be lethal."
The researchers describe their findings in a recent issue of the journal Proceedings of the National Academy of Sciences. Henkin conducted the study with Frank Grundy, a research scientist, and Susan Lehman, a research assistant. Both are with Ohio State's microbiology department.
The researchers conducted their experiments on B. subtilis in the laboratory to look for the mechanism that the bacteria uses to control the production of lysine.
"Cells are really smart – they only make what they need," Henkin said. "In this case, if there's enough lysine in the environment that they can use, or if they've already made as much as they need, the RNA binds the lysine, and turns off the lysine synthesis genes so they won't make more. But if they need lysine, the lysine-making genes are turned on.
"This is a way of controlling gene expression that scientists didn't know existed," she continued. "Everybody assumed that this kind of intracellular communication must need a regulatory protein in order to work. The gene that regulates lysine production in B. subtilis evolved its own communication system without needing to talk to a protein.”
Henkin and her colleagues have also found that production of other compounds important to bacteria, such as methionine and S-adenosylmethionine (SAM), are subject to these mechanisms.
"By studying non-pathogens with structures and functions similar to those of pathogenic bacteria, we're learning how disease-causing bacteria control their most vital physiological functions," Henkin said. "We want to use the information we gain to understand how these kinds of pathogens behave and how they control their own genes."
A grant from the National Institutes of Health supported this research.