Properties of turnip yellow mosaic virus in cesium chloride solutions: The formation of high-density components

• Published in: Virology (New York, N.Y.) Vol. 120; no. 2; pp. 412 - 421
• Main Authors: Noort, A., Van Den Dries, C.L.A.M., Pleij, C.W.A., Jaspars, E.M.J., Bosch, L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.1982
• Subjects: turnip yellow mosaic virus
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/0042-6822(82)90041-1

The bottom component B 1a of TYMV with a buoyant density of 1.42–1.43 g/ml, is converted to a more dense particle B 2a following CsCI density gradient centrifugation. This conversion is complete after a prior incubation of the virus in the CsCl solution at elevated temperatures. It is shown that the formation of B28 is accompanied with a loss from the virion of polyvalent cations like spermidine and Mg 2+. The exchange of the latter ions for Cs ions is responsible for the occurrence of the higher-density particles. The more dense component B 2a can be converted back to B,; like particles upon incubation in the presence of 0.1 M M9Cl 2. If TYMV or component B 1a is centrifuged in the presence of Mg 2+, the conversion into B 2a is prevented. The latter phenomenon allowed the isolation and characterization of the minor components B 1b and B 1c, previously postulated (Mellema et al. (1979), Virology 96, 38–46). The phenomenon of conversion appeared to be restricted to the components of the B series of TYMV; indicating that the class of light minor components does not contain artefacts of the CsCl gradient centrifugation. The formation of B 2a is accompanied by degradation of RNA, which might be due to some conformational change in the virion, rendering the RNA vulnerable to RNases.