Scientists Discover Small RNA that Regulates Bacterial Infection
Published:11 Aug.2023    Source:Georgia Institute of Technology
Pseudomonas aeruginosa, a common environmental bacterium, can colonize different body parts, such as the lungs, leading to persistent, chronic infections that can last a lifetime. But the bacteria can sometimes change their behavior and enter the bloodstream, causing chronic localized infections to become acute and potentially fatal. Marvin Whiteley and Pengbo Cao discovered a gene that drives the switch. By measuring bacterial gene expression in human tissue samples, the researchers identified a biomarker for the transition.
The researchers chose to look at human tissue samples of chronic bacterial lung and wound infections. Using genetic sequencing technologies, Whiteley and Cao measured the levels of all types of mRNA present in the bacteria. The mRNAs encode the proteins that do all the work in a cell, so by measuring a bacterium's mRNA level, one can infer the bacterium's behavior. While P. aeruginosa has roughly 6,000 genes, Whiteley and Cao found that one gene in particular -- known as PA1414 -- was more highly expressed in human tissue samples than all the other thousands of genes combined.
The researchers also found that low oxygen drives the high expression of the gene. This is a common environmental characteristic of bacterial infections, as bacteria frequently encounter oxygen deprivation during chronic infections. Further tests showed that the gene also regulates bacterial respiration under low oxygen conditions. Interestingly, the researchers found that rather than encoding a protein, the gene encodes a small RNA that plays a vital role in bacterial respiration. They named the small RNA SicX (sRNA inducer of chronic infection X).