Bacteriophage T4-induced shut-off of host-specific translation.
To study the mechanism by which bacteriophage T4 inhibits the synthesis of inducible host enzymes we measured the formation of beta-galactosidase from preformed lac mRNA. Beta-Galactosidase was induced with isopropyl-beta-D-thiogalactopyranoside in the presence of 7-azatryptophan, a tryptophan analogue that is incorporated into proteins and renders the beta-galactosidase formed inactive. The accumulated las mRNA was measured by capacity to form active beta-galactosidase after a chase of the analogue with excess tryptophan. After T4 infection the ability to form beta-galactosidase from the preformed lac mRNA was rapidly lost even when T4 infection took place in the presence of rifampin. This restriction was dependent on the multiplicity of infection. At a multiplicity of infection of 8.6, 90% of the ability to express preformed lac mRNA was lost within 30 s. The kinetics of cessation of beta-galactosidase synthesis after T4 infection indicate that infection blocks initiation of lac mRNA translation.
D001372:Aza Compounds; D002701:Chloramphenicol / Q000494:pharmacology; D003090:Coliphages / Q000254:growth & development*; D004261:DNA Replication; D004267:DNA Viruses; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology* / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000378:metabolism; D012329:RNA, Bacterial / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D012293:Rifampin / Q000494:pharmacology; D014364:Tryptophan / Q000031:analogs & derivatives / Q000494:pharmacology
D001372:Aza Compounds; D012329:RNA, Bacterial; D012333:RNA, Messenger; D007544:Isopropyl Thiogalactoside; D002701:Chloramphenicol; D014364:Tryptophan; D012293:Rifampin