Translational control of protein synthesis after infection by vesicular stomatitis virus

Abstract

Four hours after infection of BHK cells by vesicular stomatitis virus (VSV), the rate of total protein synthesis was about 65% that of uninfected cells and synthesis of the 12 to 15 predominant cellular polypeptides was reduced to a level about 25% that of control cells. As determined by in vitro translation of isolated RNA and both one-and two-dimensional gel analyses of the products, all predominant cellular mRNA's remained intact and translatable after infection. The total amount of translatable mRNA per cell increased about threefold after infection; this additional mRNA directed synthesis of the five VSV structural proteins. To determine the subcellular localization of cellular and viral mRNA before and after infection, RNA from various sizes of polysomes and nonpolysomal ribonucleoproteins (RNPs) was isolated from infected and noninfected cells and translated in vitro. Over 80% of most predominant species of cellular mRNA was bound to polysomes in control cells, and over 60% was bound in infected cells. Only 2 of the 12 predominant species of translatable cellular mRNA's were localized to the RNP fraction, both in infected and in uninfected cells. The average size of polysomes translating individual cellular mRNA's was reduced about two-to threefold after infection. For example, in uninfected cells, actin (molecular weight 42,000) mRNA was found predominantly on polysomes with 12 ribosomes; after infection it was found on polysomes with five ribosomes, the same size of polysomes that were translating VSV N (molecular weight 52,000) and M (molecular weight 35,000) mRNA. We conclude that the inhibition of cellular protein synthesis after VSV infection is due, in large measure, to competition for ribosomes by a large excess of viral mRNA. The efficiency of initiation of translation on cellular and viral mRNA's is about the same in infected cells;

Regulation of Protein Synthesis in Virus-Infected Animal Cells

“…(3) Jaye et al (1982); Lodish and Porter (1980); Nisbioka and Silverstein (1978a). (4) Lodish and Porter (1980); Otto and Lucas-Lenard (1980). (5) Francoeur and Stanners (1978); .…”

“…Whereas reovirus mRNAs appear to be less efficient than most host mRNAs, VSV mRNAs are probably translated as efficiently as host mRNAs, but not more so. Competition is simply proportional to the concentration of viral mRNAs in the cytoplasm (Lodish and Porter, 1981),8 and VSV and host mRNAs that encode the same-sized proteins are on polysomes of the same size (Lodish and Porter, 1980). In some cell lines infected by some strains of VSV, a portion of the eIF-2 pool seems to be inactivated (Centrella and Lucas-Lenard, 1982;Dratewka-Kos et al, 1984).…”

Global analysis of polysome-associated mRNA in vesicular stomatitis virus infected cells

“…Metabolic labeling studies demonstrate that 4 hours post VSV infection of baby hamster kidney cells in culture, total translation is suppressed to about 65% the level of uninfected controls [39]. Extraction of mRNA from infected cells coupled with its in vitro translation confirmed that the cellular mRNAs remain intact and are competent for translation [39].…”

mRNA Cap Methylation Influences Pathogenesis of Vesicular Stomatitis VirusIn Vivo

“…Guanine-N-7 (G-N-7) methylation of the mRNA cap structure is required for recognition of the cap by the rate-limiting factor for translation initiation, eIF-4E (28)(29)(30). Although the precise mechanism by which VSV mRNAs are translated is not fully understood, they utilize a variation of the canonical cap-dependent translational pathway that is hypersensitive to the lack of a ribosomal protein, rpL40 (30)(31)(32)(33)(34). In infected cells, host mRNA translation is rapidly inhibited through suppression of the intracellular pools of eIF-4E by a manipulation of the phosphorylation status of the 4E binding protein (4E-BP1) (35).…”

“…In infected cells, host mRNA translation is rapidly inhibited through suppression of the intracellular pools of eIF-4E by a manipulation of the phosphorylation status of the 4E binding protein (4E-BP1) (35). Nevertheless, in vitro experiments have shown that G-N-7 cap methylation facilitates translation of VSV mRNA (30,31,33,34). The biological function of mRNA cap 2=-O methylation, however, remains less well understood.…”