Catalytic utilization of eIF-2 and mRNA binding proteins are limiting in lysates from vesicular stomatitis virus infected L cells

Abstract

Infection of mouse L cells by vesicular stomatitis virus results in the inhibition of cellular protein synthesis. Lysates prepared from these infected cells are impaired in their ability of translate endogenous or exogenous cellular and viral mRNA. The ability of initiation factors from rabbit reticulocytes to stimulate protein synthesis in these lysates was examined. Preparations of eukaryotic initiation factor 2 (eIF-2) and the guanine nucleotide exchange factor (GEF) stimulated protein synthesis strongly in L cell lysates from infected cells, but only slightly in lysates from mock-infected cells. Maximal stimulation was obtained when a fraction containing eukaryotic initiation factors 4B (eIF-4B) and 4F (eIF-4F) was also present. In lysates from infected cells, these initiation factors increased endogenous cellular mRNA translation on the average 2-fold. In contrast, endogenous viral mRNA translation was increased to a much greater extent; the M protein was stimulated 8-fold, NS 5-fold, N 2.5-fold and G 12-fold. When fractions containing eIF-4B, eIF-4F or eIF-4A were added to these lysates in the presence of eIF-2, all 3 stimulated translation. Fractions containing rabbit reticulocyte initiation factors eIF-3 and eIf-6 had no effect on translation in either lysate. Lysates from infected L cells are apparently defective in the catalytic utilization of eIF-2 and deficient in mRNA binding protein activity.