Ohio State Professors Isolate Source Of Natural Methane
After years of effort, Ohio State Professors Michael Chan and Joseph Krycki have developed a picture of a unique protein. It's found in microbes that are common in many environments around the world, and it's responsible for most of the natural production of the greenhouse gas methane. WOSU's Jonathan Hickman reports.
When Ohio State Professor Michael Chan approached his colleague Joseph Krzycki about trying to understand the structure and function of a protein, neither thought it would be 12 years before they published their results. But even after 12 years, Chan still finds the protein fascinating.
"What's unusual about this protein is there's little channels in the protein where the gases go through, and so the big humongous structure, you'd see all the channels and how the different sites are connected kind of like canals, right, through the protein. . . It's a fascinating protein, and we're just making our first steps on this, and hopefully we'll make more in the future." Says Chan
Proteins are large molecules that do different kinds of jobs for a cell, whether it's one of the trillions of cells in our bodies, or a single-celled organism like a microbe. The protein that Chan and Krzycki is found in certain single-celled microbes called methanogens, which thrive in wetlands, but can be found in soils everywhere. These microbes use the protein to produce carbon dioxide and methane, a greenhouse gas that's 25 times more powerful than carbon dioxide. And as with the carbon dioxide we emit from our cars and coal plants, for these microbes, methane is a waste product.
"It's the equivalent of you and I having a bowl of bran in the morning, in the sense that it's their primary energy generation. This is to them like going down and getting a Big Mac." Says Krzycki
In order to see what the protein looks like, Chan, Krzycki, and their collaborators created crystal copies of the protein, and then used x-rays and special calculations to build a three-dimensional map of the crystals. As Chan says, sometimes the crystallization process can take a while.
"So every time we want to get crystals, we need about a year's delay. So you can imagine, part of the reason it took 12 years was because, every year, you get some crystals and you can keep trying. But we finally got it." Says Chan.
The 3-D map they made from those crystals is the key to understanding how the protein does what it does.
"We've now been able to get like a blueprint of what it looks like, and from that blueprint, we can understand how it works. It's like you have a car. You know, once you have the schematics, you can figure out how it functions. So now we have a picture of the molecule and now we can try to understand how it functions." Says Chan.
Trying to get this snapshot of the protein, Chan's first attempt to grow crystals failed, so he put his crystallization trays on the shelf and turned his attention to other projects. Two years later, the crystals had grown. But they only provide one piece of a bigger puzzle.
"For this particular project, this protein is a big protein with five pieces to it. This project has solved two of the pieces. There's three pieces left that we'd like to solve, and then we can put the whole pieces of the puzzle together and maybe get a big picture of how the whole thing works." Says Chan.
For Chan, solving the rest of the puzzle means setting up more crystallization trays and hoping for the best.
"A lot of people say you pray to the crystal gods, and maybe you'll get lucky . . . You just try many times and many different proteins and you'll get something to work, I think. [JH: a year or two down the road.] Hopefully! Hopefully not 12. That's a long time." Says Chan
The results from the first 12 years of Chan and Krzycki's research on the protein were published in the July 15th issue of the Proceedings of the National Academy of Sciences.
Jonathan Hickman, WOSU news.