The SARS virus is a type of RNA virus, meaning that its genetic material is RNA rather than the more familiar DNA found in the chromosomes of everything from bacteria to humans. All RNA viruses have relatively high mutation rates, making their genomes highly variable. In HIV, for example, this high rate of mutation contributes to the rapid appearance of drug-resistant strains of the virus. In SARS and related viruses, however, one segment of the RNA genome--known as the s2m RNA--remains virtually unchanged.
"Because viral evolution has not been able to tamper with this sequence, it is clear that it must be of vital importance to the viruses that have it, but no one knows exactly what its function is," said William Scott, an associate professor of chemistry and biochemistry at UC Santa Cruz.
Scott's lab used the technique of x-ray crystallography to solve the structure of this RNA element with nearly atomic resolution, revealing where every one of the many thousands of atoms that make up the structure is situated. The results showed several unique and interesting features of the s2m RNA, including a distinctive fold that appears to be capable of binding to certain proteins involved in regulating protein synthesis in cells.
"The structure gives us strong hints about the function, because it forms a fold that has been implicated in binding a certain class of proteins," Scott said. "The structure itself also provides a starting point for designing antiviral
Contact: Tim Stephens
University of California - Santa Cruz