Nucleolar ribosomal precursor RNA and protein metabolism in human embryo kidney cultures infected with adenovirus 12

Abstract

Adenovirus infection is known to depress the synthesis of ribosomes throughout the period of intracellular virus accumulation. During most of this time, however, the 45 S nucleolar ribosomal precursor RNA continues to be synthesized, methylated, and processed. Furthermore, the rate of incorporation of radioactive uridine or methyl-labeled methionine into the 3 main peaks of nucleolar RNA at 45 S, 32 S, and 28 S in infected cells is approximately twice that in control cells during part of the time of active virus production. Both methylated 28 S and 18 S RNA can be detected in the nucleoplasm of infected cells. It is only late in infection, when virus maturation is complete or almost complete, that the rate of uridine or methyl label uptake into the 45 S, 32 S, and 28 S nucleolar ribosomal precursor RNA species decreases markedly. Double label coelectrophoresis on sodium dodecyl sulfate-polyacrylamide gels shows extensive similarity between labeled nucleolar proteins from control cells and proteins from 50 S ribosomal particles. Adenovirus infection appears to inhibit the labeling of many nucleolar proteins that comigrate with ribosomal proteins.