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Journal of Virology, October 2004, p. 11371-11378, Vol. 78, No. 20
0022-538X/04/$08.00+0 DOI: 10.1128/JVI.78.20.11371-11378.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Liang Tang,2 John E. Johnson,2 and L. Andrew Ball1*
Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama,1 Department of Molecular Biology, The Scripps Research Institute, La Jolla, California2
Received 11 February 2004/ Accepted 18 June 2004
The genome of some icosahedral RNA viruses plays an essential role in capsid assembly and structure. In T=3 particles of the nodavirus Pariacoto virus (PaV), a remarkable 35% of the single-stranded RNA genome is icosahedrally ordered. This ordered RNA can be visualized at high resolution by X-ray crystallography as a dodecahedral cage consisting of 30 24-nucleotide A-form RNA duplex segments that each underlie a twofold icosahedral axis of the virus particle and interact extensively with the basic N-terminal region of 60 subunits of the capsid protein. To examine whether the PaV genome is a specific determinant of the RNA structure, we produced virus-like particles (VLPs) by expressing the wild-type capsid protein open reading frame from a recombinant baculovirus. VLPs produced by this system encapsidated similar total amounts of RNA as authentic virus particles, but only about 6% of this RNA was PaV specific, the rest being of cellular or baculovirus origin. Examination of the VLPs by electron cryomicroscopy and image reconstruction at 15.4-Å resolution showed that the encapsidated RNA formed a dodecahedral cage similar to that of wild-type particles. These results demonstrate that the specific nucleotide sequence of the PaV genome is not required to form the dodecahedral cage of ordered RNA.
Present address: School of Life Sciences, University of Queensland, St. Lucia 4072, Australia.
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