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Atomic force microscopy analysis of icosahedral virus RNA
Yurii G Kuznetsov1, Sarah Daijogo, Jiashu Zhou
1Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
Journal of Molecular Biology
|March 1, 2005
Summary
Viral RNA unfolds into segmented fibers and reforms spherical shapes, suggesting RNA sequence dictates conformation independently of viral proteins. This reveals dynamic RNA structures and folding mechanisms.
Area of Science:
- Virology
- Molecular Biology
- Biophysics
Background:
- Genomic RNA within viral capsids adopts specific conformations.
- Understanding RNA folding is crucial for viral assembly and function.
Purpose of the Study:
- To investigate the dynamic structural transformations of viral RNA.
- To determine if RNA sequence alone can dictate its conformation.
Main Methods:
- Extraction of single-stranded genomic RNA from poliovirus, TYMV, BMV, STMV, and TMV.
- Atomic force microscopy (AFM) imaging under dynamic conditions (temperature changes).
Main Results:
- Icosahedral viral RNAs initially formed condensed spheres, transforming into segmented fibers upon incubation.
- Helical TMV RNA initially appeared as threads, forming multidomain chains.
- Polio and STMV RNA reformed spherical shapes upon cooling, independent of proteins.
- Secondary structural elements arrange linearly along the polynucleotide chain.
Conclusions:
- Viral RNA exhibits dynamic unfolding and refolding behaviors.
- RNA base sequence may be sufficient to encode its conformation, even without coat proteins.
- This suggests an intrinsic RNA folding mechanism relevant to viral structure.