Santa Cruz, CA -- Which came first, nucleic acids or proteins? This question is molecular biology's version of the "chicken-or-the-egg" riddle. Genes made of nucleic acids (DNA or RNA) contain the instructions for making proteins, but enzymes made of proteins are needed to replicate genes. For those who try to understand how life originated, this once seemed an intractable paradox.
The solution came with the discovery 20 years ago that certain types of RNA can act as enzymes, catalyzing reactions just as enzymes made of protein do. This means, in principle, that a single type of molecule, RNA, might be able to both encode information and replicate it. The idea that the first self-replicating molecules in a pre-biotic primordial soup were composed of RNA, known as the "RNA World" hypothesis, is one of the central tenets upon which many theories of the origin of life are now based.
Research on the structure and function of RNA enzymes, or ribozymes, has been one of the main activities in the Center for the Molecular Biology of RNA at the University of California, Santa Cruz, as well as many other laboratories throughout the world. In addition to offering glimpses into how life may have originated, ribozymes are also being engineered in many academic and industrial laboratories to be therapeutic agents for potential use in fighting infectious and chronic diseases.
Scientists at UCSC's RNA Center have now obtained a near-atomic resolution image of the three-dimensional shape of a very simple--and therefore potentially understandable--ribozyme in which the atoms are uniquely arranged and poised for catalysis in the context of an intricately twisted and folded segment of RNA. The new findings are described in a paper by graduate student Monika Martick and her adviser, William Scott, associate professor of chemistry and biochemistry, in the July 27 issue of the journal Cell. The paper will be available online on July 20 at
Contact: Tim Stephens
University of California - Santa Cruz