Pathogenic bacteria Burkholderia pseudomallei produces ergothioneine that enhances its virulence

What is it about?

Bacteria use various antioxidants for protection against oxidative stress encountered during survival. Glutathione (GSH) is the most abundant and widely used antioxidant in Gram-negative bacteria, whereas ergothioneine (EGT) is mainly produced by fungi and Mycobacteria. The Burkholderia genus represents a group of Gram-negative bacteria found in diverse environmental niches, but also include members which cause disease in humans. We discovered that many species of Burkholderia possess the genes for EGT synthesis. Both pathogenic Burkholderia pseudomallei and environmental B. thailandensis are able to synthesize EGT. Unlike most other bacterial EGT synthesis pathways, Burkholderia utilize cysteine rather than y-glutamyl cysteine as one of the building blocks and there are changes to the active site of the enzyme. Despite these changes, the activity of the Burkholderial EgtB enzyme is comparable to that of Mycobacteria. In the absence of GSH, but not EGT, Burkholderia are more susceptible to oxidative stresses in vitro. However, during mouse infection, deletion of EGT synthesis resulted in a delay in bacterial colonization in the organs and mice took a longer time to die. Therefore, despite the lack of an antioxidant role in vitro, EGT is important for helping Burkholderia to better survive and cause disease in the mammalian host.

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Why is it important?

First report to show that ergothioneine is being produced by a pathogenic species of proteobacteria and the reaction and function is different from that of Mycobacteria.