SOME PROPERTIES OF 30S AND 50S PARTICLES FORMED IN ABSENCE OF PROTEIN SYNTHESIS BY PHOSPHORUS-STARVED ESCHERICHIA COLI

Phosphorus‐starved Escherichia coli ML 308 cells accumulate a limited pool of proteins which can be used to produce 30 S and 50 S particles when phosphorus is restored to the culture in the presence of chloramphenicol (100 μ/ml). These particles are resistant to dinitrophenol in vivo and to ribonuclease in vitro. The kinetics of accumulation suggest that the proteins mainly derive from pre‐existing ribosomes, although the participation of a protein fraction synthesized during phosphorus starvation has not been excluded. Phosphorus‐starved cells have been used to demonstrate that 5‐fluorouracil incorporation into rRNA completely prevents the formation of 30 S and 50 S particles even when normal ribosomal proteins are available. The rRNA present in 30 S and 50 S particles formed in the presence of chloramphenicol cannot be distinguished from the rRNA extracted from normal sub‐units by column chromatography on methylated serumalbumin‐kieselguhr and sucrose gradient sedimentation. Copyright © 1969, Wiley Blackwell. All rights reserved