Inhibitory Effect of Diphtheria Toxin on Amino Acid Incorporation in Escherichia coli Cell-Free System
AUTOR(ES)
Tsugawa, Akiko
RESUMO
The mechanism of action of diphtheria toxin in an Escherichia coli cell-free protein-synthesizing system was examined. When the washed ribosomes were incubated with toxin before addition of messenger ribonucleic acid (RNA), peptide syntheses of 14C-phenylalanine directed by polyuridylic acid or phage R17 RNA were strongly inhibited by a small amount of toxin. Whereas, if the soluble fraction (105,000 × g supernatant fraction) was preincubated with toxin, no effect of toxin occurred either on the induced protein synthesis or on the activity of guanosine triphosphatase even in the presence of nicotinamide adenine dinucleotide. The binding of 3H-formylmethionyl-transfer RNA to E. coli ribosomes directed by either R17 RNA or trinucleotide AUG was also decreased by toxin. These findings suggest that diphtheria toxin may prevent the binding of messenger RNA by successfully competing with the AUG for ribosomal binding sites. Sucrose-density gradient studies support this concept by showing the decrease in binding of 3H-labeled R17 RNA to E. coli ribosomes exposed to toxin.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=248195Documentos Relacionados
- ON THE RIBONUCLEIC ACID SYNTHESIZED IN A CELL-FREE SYSTEM OF ESCHERICHIA COLI*
- PROTEIN BIOSYNTHESIS BY A CELL-FREE BACTERIAL SYSTEM. II. FURTHER STUDIES ON THE AMINO ACID INCORPORATION ENZYME*
- Cell-Free Amino Acid-Incorporating System from Pseudomonas indigofera
- Site in Cell-free Protein Synthesis Sensitive to Diphtheria Toxin
- STIMULATION OF AMINO ACID INCORPORATION INTO PROTEIN BY NATURAL AND SYNTHETIC POLYRIBONUCLEOTIDES IN A MAMMALIAN CELL-FREE SYSTEM
