For decades, the "other" genetic material, RNA (ribonucleic acid),was thought to play a supporting role to its more famous counterpart,DNA. After all, protein production requires DNA-based geneticinformation to be converted to transient RNA molecules, which cells useas blueprints to build the proteins, in a process that relegates RNA toits subsidiary reputation. More recently, scientists have come torealize the range of RNA functions is much broader than as mere middlemen in protein production. Indeed, RNA also mediates chemical reactionsand regulates cellular processes.
Now, articles in the Sept. 2 issue of the journal Science provide arich resource for scientists to study the diversity and function of aspecial class of RNAs and demonstrate yet another role for themysterious molecule beyond protein production.
In one, a group at the University of Delaware used a new techniqueto identify more than 77,000 so-called "small RNAs" from the modelplant, Arabidopsis thaliana, and created a publicly accessible databaseto hold the information. In a second article, a Yale University teamdetermined the structure of an RNA molecule that aids in chemicalreactions and found it had characteristics resembling proteins thatperform similar reactions, raising the possibility that RNA-basedmolecules could have served many roles in Earth's earliest history.
Over the past 10 years, a number of research teams have furtherexplored a discovery that certain small RNAs constitute a potent set ofmolecules that can regulate cellular processes including development,defense against disease-causing microbes and stress response. Althoughseveral thousand small RNAs have been identified from diverse plant andanimal systems, the technology was not available to catalog the fullset in any organism.
Pamela Green and Blake Meyers and their coworkers at the Universityof Delaware capitalized on a new technique developed by Solexa, Inc.,Hayward, Calif., to characterize the small RNAs in Arabidopsis. The newdata provide the foundation to elucidate the identity, regulation andfunction of small RNAs in both plants and animals. They have made thedata accessible via a user-friendly, web-based, public database thatscientists around the world can use to compare Arabidopsis genomesequences to the cache of newly discovered small RNAs.
Joanne Tornow, a National Science Foundation (NSF) program managersaid, "Understanding the molecular underpinnings of biologicalprocesses is essential to our goal of comprehending life's complexity.These new results will be of tremendous benefit to the scientificcommunity." The work was supported through NSF's "Small Grants forExploratory Research" program, which sponsors high-risk research thatmay lead to rapid, innovative advances in science and engineering.
Further demontrating RNA's varied functions, Yale's Mary Stahley andScott Strobel focused on an RNA molecule that uses magnesium ions tocatalyze chemical reactions that occur during the protein productionprocess. They determined the 3-D structure of the magnesium-RNA complexand discovered that the RNA had a similar structure to proteins thatuse magnesium to catalyze reactions in a like manner.
"The knowledge gained from this work will be useful in futureefforts to design and engineer new RNA-based molecules that can performreactions in biochemical nanoengineering," said Parag Chitnis, NSFprogram manager for the project.
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