Date of Original Version
An mRNA-ribonucleoprotein particle (mRNP) was found in vesicular stomatitis virus (VSV)-infected Chinese hamster ovary cells. The particle was present 3 and 4.5 h after infection but was barely discernible at 2 h. The mRNP (buoyant density, 1.56 g/cm3), which cosedimented with viral nucleocapsid in a sucrose density gradient at approximately 120 to 160S, was separable from nucleocapsid (buoyant density, 1.31 g/cm3) by CsCl density gradient centrifugation. It contained all five VSV mRNAs and, almost exclusively, viral N protein. Some host mRNA and host protein was also present in the particle. The intact mRNP was incapable of stimulating protein synthesis in an in vitro protein-synthesizing system, although the VSV mRNA isolated from the particle by phenol extraction was functional in vitro. In contrast, intact polysomes stimulated cell-free protein synthesis to the same extent as purified polysomal mRNA. By 4.5 h after infection, 97% of the functional mRNA in vivo was associated with the mRNP, and only 3% was on polysomes. The amount of polysomal mRNA at 4.5 h after infection was only 31% of that found at 2 h after infection; this was reflected by the 76% decrease observed in the rate of in vivo protein synthesis at 4.5 h relative to that found at 2 h. Thus, it appears that the mRNP serves as an organelle which sequesters the large excess of VSV mRNA that is normally made during secondary transcription.
Translational Control of Vesicular Stomatitis Virus Protein Synthesis: Isolation of an mRNA-Sequestering Particle. J. Virology, 44(3), 932-938. Retrieved from http://jvi.asm.org/content/44/3/932.
Available at: http://jvi.asm.org/content/44/3/932