The next task was to uncover the mechanism that triggered the bacteria to ingest iron-citrate. Computer modeling predicted that a single Streptomyces gene enabled the bacteria to identify and ingest iron-citrate. The researchers isolated the gene and added it to E. coli bacteria (which is not an Actinomycete bacteria). They found that the mutant E. coli bacteria could also ingest iron-citrate. Without the gene, E. coli could not gain access to the iron.
"It's amazing that the bacteria could learn to extract iron from their environment in this way," Doyle says. "We went into these experiments with no idea that this mechanism existed. But then, bacteria have to be creative to survive in some very hostile environments; and they've had maybe 3.5 billion years to figure it out."
The Streptomyces gene enables the bacteria to passively diffuse iron-citrate across the cell membrane, which means that the bacteria do not expend additional energy to ingest the iron. Once in the cell, the bacteria metabolize the iron and, as an added bonus, use the citrate as an energy source. Doyle's team is the first to identify this mechanism in a bacteria belonging to the Actinomycete family. The team plans further experiments to confirm that the gene performs the same signaling function in tuberculosis bacteria. If so, the mechanism could potentially be exploited in the fight against tuberculosis.
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| Contact: Sara Miller semortim@syr.edu 315-443-9038 Syracuse University Source:Eurekalert |