Edmondson SP, Gray DM. A circular dichroism study of the structure of Penicillium chrysogenum mycovirus.
Nucleic Acids Res 1983;
11:175-92. [PMID:
6408610 PMCID:
PMC325697 DOI:
10.1093/nar/11.1.175]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
We have examined the absorption and circular dichroism spectra of intact Penicillium chrysogenum virus, empty capsid particles, and isolated double-stranded RNA. The absorbance at 260 nm of intact virus was less than 4% hypochromic relative to the absorbances of the free double-stranded RNA and free viral protein, indicating very little change in the base stacking interactions of the RNA. Circular dichroism studies of intact virus indicate that the capsid protein consists of 45% alpha-helix. Empty capsids, containing a protein of the same molecular weight as intact virus protein, were found to have 30% alpha-helix, suggesting a conformational change in the capsid upon assembly with RNA. The conformation of double-stranded RNA in the virus was slightly altered from the solution structure of the RNA in 0.01 M Na+ and resembled the conformation of double-stranded RNA partially bound with spermidine. However, the virus does not appear to contain polyamines. Electrophoretic experiments indicate a pH- and salt-titratable RNA binding site on the capsid protein in virus disrupted by urea or non-ionic detergents. The results are consistent with significant ionic interactions between the RNA and the capsid protein in the virus.
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