Linear variation in stability of tobacco mosaic virus to stripping of protein by detergent

• Published in: Virology (New York, N.Y.) Vol. 38; no. 2; pp. 309 - 316
• Main Author: Symington, Janey
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.1969
• Subjects: Carbon Isotopes; Detergents - pharmacology; Hot Temperature; Leucine - metabolism; Microscopy, Electron; Orotic Acid - metabolism; RNA, Viral; Tobacco Mosaic Virus - drug effects; Tobacco Mosaic Virus - metabolism; Viral Proteins
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1016/0042-6822(69)90372-9

When protein is stripped from tobacco mosaic virus (TMV) by heat-detergent treatment, the position of the rod length frequency distribution mode varies discontinuously as the mean length decreases. This is evidence of a variation in stability of protein subunits to detergent stripping along the length of the rod. The region close to the 300 mμ monomer length is quite stable. As treatment proceeds, the rod length is decreased readily between 260 and 225 mμ, protein subunits being removed from the 5′-linked end of this unstable region. As the rod is further shortened, there is a more stable region between 225 mμ and the midpoint of the rod. As the length is still further decreased, there is an unstable region of about 50 mμ. This may be located adjacent to the center of the rod if stripping continues from the 5′-linked end. There is a possibility, however, that the other end of the rod begins to be stripped, since shortened rods with ribonucleic acid (RNA) exposed at both ends have been observed in electron micrographs of extensively stripped preparations. Below 100 mμ in length the rod is again quite stable, the mode decreasing with the mean length. The conclusion that the stability of TMV varies along the rod is also supported by a variation in sample length homogeneity with increasing severity of treatment. The spread to include 68% of the particles is least when no stripping or very little has occurred. Another minimum in the spread is found when the mean length is 200 mμ. This increased length homogeneity indicates special stability at this point. Due to the bimodal distribution on longer treatment the spread increases until the mean length is less than 100 mμ. After this extensive stripping the mode is between 20 and 50 mμ. There is a decreased spread in this stable rod length region. Relatively few rods are degraded completely by short stripping. When less than 70% of the protein has been removed the RNA remains attached. Beyond 70%, breakage of RNA increases considerably, as does the percentage of completely disassembled rods.