This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Moehring, T. J. Articles by Moehring, J. M. Search for Related Content PubMed PubMed Citation Articles by Moehring, T. J. Articles by Moehring, J. M.

 Previous Article  |  Next Article 

J Bacteriol. 1968 July; 96(1): 61-69
Copyright © 1968 American Society for Microbiology. All Rights Reserved.

Response of Cultured Mammalian Cells to Diphtheria Toxin III. Inhibition of Protein Synthesis Studied at the Subcellular Level

^a Department of Medical Microbiology, Stanford University, Stanford, California 94305

ABSTRACT

Diphtheria toxin inhibited protein synthesis in intact KB cells. The action of the toxin upon the cell did not result in disaggregation of polyribosomes, or in impairment of their ability to function in protein synthesis. A reduction in single ribosomes and a concomitant increase in polyribosomes did result from the action of toxin. Nascent peptides were not cleaved from polyribosomes by the action of toxin, but treatment of fully intoxicated cells with puromycin resulted in cleavage of these peptides, and caused accelerated polyribosome breakdown. Our data indicated that the toxin must enter the cell to exert its effect. The component or components sensitive to toxin were localized in the 100,000 x g supernatant fraction of cytoplasmic extracts. When extracts from intoxicated cells were treated with nicotinamide, a significant proportion of their capacity to synthesize protein was restored. The specificity of this reaction suggested that nicotinamide adenine dinucleotide is involved in the action of toxin in the intact cell, and that one component inactivated by toxin is soluble transferase II.

¹ Present address: Department of Medical Microbiology, The University of Vermont, College of Medicine, Burlington, Vt. 05401