Discovery Could Develop New Way to Kill Salmonella
Source of Article: http://www.laboratoryequipment.com/news-research-finds-way-kill-salmonella-080709.aspx?xmlmenuid=51
August 7, 2009
Scientists from Ireland, the UK and Germany have discovered a new type of gene regulation in Salmonella that gives insight into the causes of bacterial infection. The discovery of this new mechanism of gene regulation could eventually lead to the development of innovative therapies and reduce the levels of disease caused by Salmonella.
Salmonella causes food poisoning and kills around 1 million people worldwide every year. The bacteria are particularly effective at causing human infection because they can survive a series of harsh conditions which include strong acids in the stomach and the anaerobic and salty environment of the intestine that kill most bacteria.
To survive, Salmonella genes are switched on and off quickly inside the human body in reaction to these harsh conditions. This process involves continuous remodelling of the bacterial surface by adding outer membrane proteins (OMPs) to the cell wall to cope with the new environment.
Research by scientists from Trinity College Dublin, the Institute of Food Research in the UK and the Max Planck Institute for Infection Biology just published in the journal Nature Structural & Molecular Biology, reveals a new mechanism used by Salmonella to control levels of a particular OMP (OmpD) by molecules called small RNAs (sRNAs). sRNAs bind to the messenger RNA (mRNA) that is responsible for making the protein. OmpD is a vital surface protein that allows Salmonella to survive salty environments and to kill people.
Professor Jay Hinton at Trinity College said: "We discovered that an sRNA called MicC can switch off a protein by binding to mRNA with a new and unexpected mechanism. Until now, binding of sRNAs was thought to be limited to just 1% of the bacterial chromosome. We discovered that the MicC sRNA can bind at any position within a gene's mRNA".
"Because MicC can bind to virtually anywhere on the chromosome it provides Salmonella with an efficient method of switching off proteins such as OMPs. By controlling OmpD, MicC helps Salmonella to thrive in salty conditions and to infect humans. This mechanism solves a long-standing mystery, because it had been thought that bacteria only used sRNAs in a primitive way. Our discovery unifies a whole area of biology - now we know that bacteria can use the same sophisticated mechanism found in plants and animals".
"This breakthrough reveals another tactic that Salmonella uses to cause disease. We hope that in the future scientists will be able to use the findings to develop new ways to kill Salmonella. It is an exciting step on the path of reducing the levels of Salmonella and reducing human disease worldwide," said Hinton.
The researchers used cutting edge microarray technology to search the 5,000 genes in the Salmonella genome for the targets to which the MicC sRNA bound. They then confirmed these results by a combination of biochemistry and molecular biology.
Source: Trinity College Dublin
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