Journal of General Virology

Visualization by atomic force microscopy of tobacco mosaic virus movement protein–RNA complexes formed in vitro

O. I. Kiselyova,¹ I. V. Yaminsky,¹ E. M. Karger,² O. Yu. Frolova,² Y. L. Dorokhov² and J. G. Atabekov²

Faculty of Physics and Faculty of Chemistry¹, Department of Virology and A. N. Belozersky Institute of Physico-Chemical Biology², Moscow State University, Vorobiovy Gory, Moscow 119899, Russia

The structure of complexes formed in vitro by tobacco mosaic virus (TMV)-coded movement protein (MP) with TMV RNA and short (890 nt) synthetic RNA transcripts was visualized by atomic force microscopy on a mica surface. MP molecules were found to be distributed along the chain of RNA and the structure of MP–RNA complexes depended on the molar MP:RNA ratios at which the complexes were formed. A rise in the molar MP:TMV RNA ratio from 20:1 to 60–100:1 resulted in an increase in the density of the MP packaging on TMV RNA and structural conversion of complexes from RNase-sensitive 'beads-on-a-string' into a 'thick string' form that was partly resistant to RNase. The 'thick string'-type RNase-resistant complexes were also produced by short synthetic RNA transcripts at different MP:RNA ratios. The 'thick string' complexes are suggested to represent clusters of MP molecules cooperatively bound to discrete regions of TMV RNA and separated by protein-free RNA segments.

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© 2001 SGM

This article is now available in the June 2001 print issue of JGV (vol. 82, 1503–1508). The complete issue of the journal may be seen in electronic form on JGV Online.