A three-stemmed mRNA pseudoknot in the SARS coronavirus frameshift signal |
| |
Authors: | Plant Ewan P Pérez-Alvarado Gabriela C Jacobs Jonathan L Mukhopadhyay Bani Hennig Mirko Dinman Jonathan D |
| |
Institution: | 1
Department of Cell Biology and Molecular Genetics, University of Maryland
College Park, Maryland
United States of America;2
Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute
La Jolla, California
United States of America;University of Wisconsin
United States of America |
| |
Abstract: | A wide range of RNA viruses use programmed −1 ribosomal frameshifting for the production of viral fusion proteins. Inspection of the overlap regions between ORF1a and ORF1b of the SARS-CoV genome revealed that, similar to all coronaviruses, a programmed −1 ribosomal frameshift could be used by the virus to produce a fusion protein. Computational analyses of the frameshift signal predicted the presence of an mRNA pseudoknot containing three double-stranded RNA stem structures rather than two. Phylogenetic analyses showed the conservation of potential three-stemmed pseudoknots in the frameshift signals of all other coronaviruses in the GenBank database. Though the presence of the three-stemmed structure is supported by nuclease mapping and two-dimensional nuclear magnetic resonance studies, our findings suggest that interactions between the stem structures may result in local distortions in the A-form RNA. These distortions are particularly evident in the vicinity of predicted A-bulges in stems 2 and 3. In vitro and in vivo frameshifting assays showed that the SARS-CoV frameshift signal is functionally similar to other viral frameshift signals: it promotes efficient frameshifting in all of the standard assay systems, and it is sensitive to a drug and a genetic mutation that are known to affect frameshifting efficiency of a yeast virus. Mutagenesis studies reveal that both the specific sequences and structures of stems 2 and 3 are important for efficient frameshifting. We have identified a new RNA structural motif that is capable of promoting efficient programmed ribosomal frameshifting. The high degree of conservation of three-stemmed mRNA pseudoknot structures among the coronaviruses suggests that this presents a novel target for antiviral therapeutics. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
| 点击此处可从《PLoS Biology》浏览原始摘要信息 |
| 点击此处可从《PLoS Biology》下载免费的PDF全文 |