Research on toxic metal could save lives

La Trobe University, in collaboration with University of Adelaide and University of Queensland, has uncovered how the metal cadmium, which is accumulating in the food chain, causes toxicity in living cells.

The research, which will be published in Nature Communications journal tomorrow, is the first step of a long-range strategy to develop new life-saving treatments for deadly bacterial diseases. 

All life needs trace metal nutrients (iron, zinc etc), however, some trace metals such as cadmium are toxic. The findings of this work are significant in that they have revealed the mechanisms of this toxicity.

For example, the metal cadmium – which is commonly found in batteries and industrial waste – exerts its toxicity by effecting the way cells regulate and absorb essential metals such as manganese and zinc.  

It is estimated humans ingest 30 micrograms of cadmium each day as the metal is absorbed through soil and water into the food chain. 

Using this greater understanding of how essential trace metals are balanced within cells, researchers hope to develop a new strategy for antibiotic design, to tackle bacteria – specifically Streptococcus pneumoniae,which is the leading infectious cause of death for children under five worldwide. 

Senior Researcher at the La Trobe Institute for Molecular Science (LIMS), Megan Maher, said the knowledge would not only help scientists understand how cadmium poisons cells, but also allow them to better understand how the balance of trace elements within cells is maintained. 

"By understanding what nutrients cells need to thrive, we hope to design a strategy to deny harmful bacteria of the nutrients they need, essentially killing the organisms," Dr Maher said.  

"We originally thought that heavy metals (such as cadmium) themselves were toxic to cells, but we've since discovered they actually accumulate in cells and interfere with the way cells regulate. Cadmium interferes with the ability of this bacterium to acquire the trace elements it needs. 
"We studied the Streptococcus pneumoniae bacterium specifically. All life needs trace nutrition and by understanding what that bacteria needs and how it acquires it, we can tackle the trace metal absorption. We're hoping that by blocking the uptake, we can develop new antibiotic treatment strategies." 

Project leader Dr Christopher McDevitt, who is Deputy Director of University of Adelaide's Research Centre for Infectious Diseases, said the findings were crucial for developing new strategies to prevent cadmium poisoning.  

"Exposure to cadmium can occur due to poor disposal of industrial or electronics waste, and also through cigarette smoke and ingestion of contaminated food," Dr McDevitt said. 

"While the toxicity of cadmium has been known for a long time, how it causes toxicity and damages cells hasn't been understood.  "We've shown, in a model bacterial system, that the chemistry of cadmium allows it to bypass the mechanisms that prevent other metals, such as irons and zinc, from freely entering cells."

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Image: Microbe World

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