Researchers from the University of Barcelona have found an essential regulatory mechanism in the infectious process of salmonella, a bacterium related to several gastrointestinal diseases such as salmonellosis. The study, published in the journal PLOS Pathogens, shows that the regulation in the transcriptional elongation, the first step of the process of expression of the information in the DNA, is essential in the Salmonella virulence. This research enables analyzing the mechanisms used by bacteria to control the genic expression and it could contribute to the development of new vaccines in the long run.
The study is led by Carlos Balsalobre, professor from the Department of Genetics, Microbiology and Statistics of the UB. The study counts with the participation of the UB experts Tania Gaviria-Cantin and Youssef El Mouali, and the researchers from Karolinska Institute (Stockholm) Soazig Le Guyon and Ute Römling.
Essential proteins in the infection
The study focused on the bacterium Salmonella enterica, an enteric pathogen that can cause from a light gastroenteritis to severe systemic infections in humans. The S. enterica invades epithelial cells in order to develop the infection successfully, a process requiring the coordinated expression of a series of genes. In particular, researchers have analyzed the role of the Gre factors, proteins that act during the transcriptional elongation, involved in the release of pauses which occur during this process. “The study describes how these proteins are necessary for the HilD expression, an essential regulator that controls the expression of numerous important virulence factors during the Salmonella infection process” says Carlos Balsalobre.
“According to our experiments with cell cultures and mice models –added the researcher-, Salmonella strains without Gre factors are not as virulent as the regular strains, since they cannot invade epithelial cells and colonize organs”.
During decades, the studies on the regulation of bacterial genic expression have been particularly focused on the regulation that occurs at the beginning of the transcription. These results show that regulation during the transcriptional elongation stage can be relevant. “With these studies we can consider studying the role of these factors in the general pattern of transcriptional expression, both in Salmonella itself and bacteria in general” concluded the researcher.
Tania Gaviria Cantin, Youssef El Mouali, Soazig Le Guyon, Ute Römling and Carlos Balsalobre. «Gre factors-mediated control of hilD transcription is essential for the invasion of epithelial cells by Salmonella enterica serovar Typhimurium». PLOS Pathogen, April 2017. Doi: https://doi.org/10.1371/journal.ppat.1006312
Universitat de Barcelona