Using state-of-the-art techniques, the team catalogued the metals in three microbes: one that lives in human intestines, one plucked from a hotspring in Yellowstone National Park, and one that thrives in the near-boiling waters of undersea thermal vents.
They uncovered a microbial world far richer in metals than ever expected. For example, in the undersea thermal-vent loving microbe, or Pyrococcus furiosus, they found metals such as lead, manganese, and molybdenum that P. furiosus wasn't known to use.
The scientists traced these newfound metals to the proteins that contain them, called metalloproteins. They discovered four new metalloproteins in the microbe, which increased the number of known metalloproteins in P. furiosus by almost a quarter. Their discovery also increased the number of nickel-containing enzymes in all of biology from eight to ten.
A similar survey of the other two microbes unearthed additional unexpected metals and new metalloproteins. Based on this sizeable haul from only three microbes, the team believes that metalloproteins are much more extensive and diverse in the microbial world than scientists realized.
"We thought we knew most of the metalloproteins out there," says Tainer. "But it turns out we only know a tiny fraction of them. We now have to look at microbial genomes with a fresh eye."
The team used a first-of-its-kind combination of two techniques to envisage this uncharted microbial landscape. Biochemical fractionation enabled them to take apart a microbe while keeping its proteins intact and stable, ready to be analyzed in their natural state. Next, a technology called inductively coupled plasma mass spectrometry allowed them to identify extremely low quantities of individual metals in these proteins.
Together, these tools provide a quick tally of the metalloproteins in a microbe.
The current way to discover metalloprotein
|Contact: Dan Krotz|
DOE/Lawrence Berkeley National Laboratory