Internal cellular sensors make Salmonella dangerous: study

Jun 15, 2012 By Bill Hathaway
Salmonella bacteria (in green) are engulfed by immune system cell called a macrophage. The direct threat from the immune cell activates genes that trigger the organism to become virulent and dangerous to the host.

(Phys.org) -- Salmonella becomes dangerously virulent only when molecular sensors within the organism sense changes in the environment, a team of researchers from the Yale School of Medicine and the Yale Microbial Diversity Institute report in the June 14 issue of the journal Nature.

Other probably possess analogous sensors to activate and cause maladies such as and tuberculosis, the authors suggest. This mechanism may present a novel target for drugs that can disarm bacteria’s ability to cause disease, said Eduardo A. Groisman, professor of microbial pathogenesis at the Yale School of Medicine and an investigator with the Howard Hughes Medical Institute.

“There will never be a world without because it exists in many, many animal reservoirs,” Groisman said. “So you can try to avoid getting Salmonella or learn how to fight it.  Hundreds of thousands of people die from Salmonella poisoning each year, and tens of millions of people are infected. It is a major public health issue.”

Groisman and Eun-Jin Lee of Yale investigated whether signals from outside the bacteria triggered one of its virulence genes. The researchers meticulously tracked the molecular chain reaction that occurs after Salmonella becomes engulfed by macrophages, immune system cells that respond to bacterial invaders. Salmonella then can reproduce rapidly, often overwhelming defenses of the host.

The Nature paper discovers that it is not the direct threat from the environment itself that triggers the virulence gene within the bacterium. Instead, changes in the level of acidity in Salmonella’s surroundings trigger an increase in levels of ATP, the energy currency of all cells. It is the change in ATP levels within the organism that activates virulence factors and enables Salmonella to survive within its host.

This internal sensor acts in concert with several other factors necessary before these bacteria can become virulent, Groisman said. Understanding all these processes should help scientists develop defenses against infectious diseases, he adds.

Explore further: NYSCF Research Institute announces largest-ever stem cell repository

Related Stories

Salmonella: Trickier than we imagined

Jun 13, 2008

Salmonella is serving up a surprise not only for tomato lovers around the country but also for scientists who study the rod-shaped bacterium that causes misery for millions of people.

Recommended for you

Crowdsourced power to solve microbe mysteries

19 hours ago

University of New South Wales scientists hope to unlock the secrets of millions of marine microbes from waters as far apart as Sydney's Botany Bay and the Amazon River in Brazil, with the help of an international ...

Reading a biological clock in the dark

Oct 21, 2014

Our species' waking and sleeping cycles – shaped in millions of years of evolution – have been turned upside down within a single century with the advent of electric lighting and airplanes. As a result, ...

User comments : 0