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Metal ions tell bacteria where they are

Effect of zinc, copper and manganese in Enterococcus gene expression

Oeiras, 18.11.11

Have you ever wondered how bacteria realize they are inside the host? And once there, where in the host? These questions are particularly important for bacteria, such as Enterococcus faecalis, that are both part of our body’s commensal microbes and able to cause serious infections in hospitalized patients. In an attempt find answers, the SAVE Lab from ITQB, together with Jan Kok from the  University of Groningen, The Netherlands, analyzed the E. faecalis response to three metal ions (zinc, copper and manganese) that could help bacteria discriminate between different environments. The findings are published in PLoS ONE.

When entering the body, both via mouth or through the skin, E. faecalis come across different tissues and barriers. Since their behavior is different in different organs, tissues or body fluids, bacteria must be able to modulate gene expression according to the environment. So, there must be something in the different host environments that allows bacteria to tell the difference. Some metals ions, such as zinc, copper and manganese, have different concentrations in different fluids and are thus likely candidates for discrimination. For example, zinc concentration in saliva and in the lungs can be ten to twenty times higher than in serum or in gastric juice; and manganese is 1000-fold more concentrated in saliva than in blood or urine. By comparing E. faecalis subjected to low and high concentrations of ions, researchers were able to identify genes that behave differently, more or less active, under different circumstances.

The study now published was in line with previous findings from other researchers, who analyzed the bacteria gene expression in different environments, namely in urine and blood; many of the genes found to be differentially expressed in these samples were also found in this study. Further analysis revealed that metal ions trigger, or tone down, the expression of genes necessary for E. faecalis colonization and virulence and might thus be important for the outcome of the interaction between bacteria and host.

Original Article

PLoS ONE (2011) 6 (10):| e26519
Impact of Manganese, Copper and Zinc Ions on the Transcriptome of the Nosocomial Pathogen Enterococcus faecalis V583

Marta Coelho Abrantes, Maria de Fátima Lopes*, Jan Kok


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