Macromolecular Synthesis and Radiosensitivity in Escherichia coli

Abstract

A number of strains of Escherichia coli develop radioresistance in the stationary phase when glucose is present in a natural growth medium. Cells grown in such a medium have a large excess of macromolecules per cell, compared with cells grown to the same phase of the growth cycle in the same medium without this carbon source. The amounts of the various classes of ribosomes found in extracts of resistant and sensitive cells are different; the excess RNA in resistant cells is accounted for largely by the amount of 30S and 50S ribosomal particles. A correlation has been made between radio-resistance and ability to initiate rapid new protein synthesis. In several strains this capacity to synthesize protein correlates with the types of ribosomes present in the cell. Quantitation of the apparent correlations demonstrated here has not been carried out. Such data can result only from better understanding of the multicomponent systems involved in these complex syntheses.