Sparsomycin Modification of the Lethal Action of Ionizing Irradiation on Escherichia coli

Microbiological studies on the mechanism of action of sparsomycin

A primary site of sparsomycin attack in Escherichia coli appears to be inhibition of synthesis of protein, which occurs at concentrations of sparsomycin that do not affect DNA or RNA synthesis. Sparsomycin interferes with the normal excretion of amino acids by E. coli. Some cross-resistance was observed between a culture resistant to sparsomycin and cultures resistant to other inhibitors of protein synthesis.

Modification of radiation damage of bacteria by folic acid antagonists

Pittillo, Robert F. (Southern Research Institute, Birmingham, Ala.), Mary Lucas, Robert T. Blackwell, and Carolyn Woolley. Modification of radiation damage of bacteria by folic acid antagonists. J. Bacteriol. 90:1548-1551. 1965.-The folic acid analogues, 2,4-diamino-6-methylpteridine, amethopterin, and aminopterin, have been found to sensitize certain bacteria, especially Escherichia coli, to the lethal action of ionizing irradiation. Data are presented which indicate that (i) the compounds must be present during the irradiation period for maximal sensitization to be observed, (ii) the sensitizing effect can be nullified by cysteine or cysteamine, (iii) the sensitizing effect occurs in a number of diverse bacterial genera, and (iv) folic acid neither sensitizes bacteria to irradiation nor prevents the sensitization caused by these antifolic agents.