Looking at the crystal, the scientists saw two things, Golden said. One was that this protein uses two completely different molecular surfaces to perform its two roles. The second is that the protein seems to perform the same job that RNA performed in other simple organisms.
"The crystal structure provides a snapshot of how, during evolution, protein molecules came to assist RNA molecules in their biological functions and ultimately assumed roles previously played by RNA," Golden said.
Before the crystallization, Lambowitz, Paukstelis and their research team at The University of Texas at Austin were involved in a long-term project to study the function of the basic cellular workhorse protein and other evolutionary fossils from the fungus. In earlier work, the scientists studied a different protein that showed how biochemical processes could progress from a world with RNA and protein to DNA.
The protein, as found in the fungus, had adapted to take over some of the RNA molecule's chemical reaction jobs inside cells. The protein stabilizes the RNA molecule - called an intron - so that the RNA can cut out non-functional genetic material and splice together the ends of a functional gene, Paukstelis said.
"The RNA molecule in our study is capable of performing a specific chemical reaction on itself, but it requires a protein for this reaction to take place efficiently," he said.
This basic scientific information eventually could lead to clinical applications.
"This work has potential applications in the development of antifungal drugs to battle potentially deadly pathogens; that's one of the next steps," Lambowitz said. "Another is to produce more detailed structures so that we can understand the ancient chemical reactions."
|Contact: Susan A. Steeves|