Abstract
The mechanism by which virions of cowpea chlorotic mottle virus (CCMV) disassemble and allow for translation of the virion RNA is not well understood. Previous models have suggested that virion swelling is required to expose the virion RNA for translation in a process referred to as cotranslational disassembly (M. Brisco, R. Hull, and T. M. A. Wilson, Virology 148:210-217, 1986; J. W. Roenhorst, J. W. M. van Lent, and B. J. M. Verduin, Virology 164:91-98, 1988; J. W. Roenhorst, J. M. Verduin, and R. W. Goldbach, Virology 168:138-146, 1989). Previous work in our laboratory has identified point mutations in the CCMV coat protein which result in virions with altered swelling characteristics (J. Fox, F. G. Albert, J. Speir, and M. J. Young, Virology 227:229-233, 1997; J. M. Fox, X. Zhao, J. A. Speir, and M. J. Young, Virology 222:115-122, 1996). The wild-type and mutant CCMV virions were used to correlate virion swelling with the ability of virion RNA to be translated in a cell-free wheat germ extract. Mutant virions unable to swell (cpK42R) are as infectious as wild-type virions in vivo, and the levels of translated encapsidated virion RNA are similar to those of wild-type virions in vitro. Mutant virions capable of swelling but not of disassembling in vitro (cpR26C) are noninfectious and have severely reduced levels of translation of the encapsidated virion RNA in vitro. These studies suggest that virion swelling is not required for the cotranslational disassembly of CCMV. Additionally, the results indicate that there is a pH-dependent structural transition in the virion, other than swelling, that results in the RNA's being exposed for translation in vitro. An alternative model suggesting that cotranslational disassembly of CCMV involves presentation of the virion RNA through the virion fivefold axis is proposed.
Full Text
The Full Text of this article is available as a PDF (265.2 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Ahlquist P. Bromovirus RNA replication and transcription. Curr Opin Genet Dev. 1992 Feb;2(1):71–76. doi: 10.1016/s0959-437x(05)80325-9. [DOI] [PubMed] [Google Scholar]
- Bancroft J. B., Bracker C. E., Wagner G. W. Structures derived from cowpea chlorotic mottle and brome mosaic virus protein. Virology. 1969 Jun;38(2):324–335. doi: 10.1016/0042-6822(69)90374-2. [DOI] [PubMed] [Google Scholar]
- Bancroft J. B., McLean G. D., Rees M. W., Short M. N. The effect of an arginyl to a cysteinyl replacement on the uncoating behaviour of a spherical plant virus. Virology. 1971 Sep;45(3):707–715. doi: 10.1016/0042-6822(71)90184-x. [DOI] [PubMed] [Google Scholar]
- Cheng R. H., Reddy V. S., Olson N. H., Fisher A. J., Baker T. S., Johnson J. E. Functional implications of quasi-equivalence in a T = 3 icosahedral animal virus established by cryo-electron microscopy and X-ray crystallography. Structure. 1994 Apr 15;2(4):271–282. doi: 10.1016/s0969-2126(00)00029-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fox J. M., Albert F. G., Speir J. A., Young M. J. Characterization of a disassembly deficient mutant of cowpea chlorotic mottle virus. Virology. 1997 Jan 6;227(1):229–233. doi: 10.1006/viro.1996.8292. [DOI] [PubMed] [Google Scholar]
- Fox J. M., Zhao X., Speir J. A., Young M. J. Analysis of a salt stable mutant of cowpea chlorotic mottle virus. Virology. 1996 Aug 1;222(1):115–122. doi: 10.1006/viro.1996.0402. [DOI] [PubMed] [Google Scholar]
- Fricks C. E., Hogle J. M. Cell-induced conformational change in poliovirus: externalization of the amino terminus of VP1 is responsible for liposome binding. J Virol. 1990 May;64(5):1934–1945. doi: 10.1128/jvi.64.5.1934-1945.1990. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Munshi S., Liljas L., Cavarelli J., Bomu W., McKinney B., Reddy V., Johnson J. E. The 2.8 A structure of a T = 4 animal virus and its implications for membrane translocation of RNA. J Mol Biol. 1996 Aug 9;261(1):1–10. doi: 10.1006/jmbi.1996.0437. [DOI] [PubMed] [Google Scholar]
- Roenhorst J. W., Verduin B. J., Goldbach R. W. Virus-ribosome complexes from cell-free translation systems supplemented with cowpea chlorotic mottle virus particles. Virology. 1989 Jan;168(1):138–146. doi: 10.1016/0042-6822(89)90412-1. [DOI] [PubMed] [Google Scholar]
- Roenhorst J. W., van Lent J. W., Verduin B. J. Binding of cowpea chlorotic mottle virus to cowpea protoplasts and relation of binding to virus entry and infection. Virology. 1988 May;164(1):91–98. doi: 10.1016/0042-6822(88)90623-x. [DOI] [PubMed] [Google Scholar]
- Speir J. A., Munshi S., Wang G., Baker T. S., Johnson J. E. Structures of the native and swollen forms of cowpea chlorotic mottle virus determined by X-ray crystallography and cryo-electron microscopy. Structure. 1995 Jan 15;3(1):63–78. doi: 10.1016/s0969-2126(01)00135-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zhao X., Fox J. M., Olson N. H., Baker T. S., Young M. J. In vitro assembly of cowpea chlorotic mottle virus from coat protein expressed in Escherichia coli and in vitro-transcribed viral cDNA. Virology. 1995 Mar 10;207(2):486–494. doi: 10.1006/viro.1995.1108. [DOI] [PubMed] [Google Scholar]