Feedback regulation of rRNA and tRNA synthesis and accumulation of free ribosomes after conditional expression of rRNA genes.
We have constructed a conditional rRNA gene expression system by fusing a plasmid-encoded rrnB operon to the lambda PL promoter/operator. It was thereby possible to study the events that lead to the regulation of chromosomal rRNA and tRNA synthesis after overproduction of rRNA. rRNA induction resulted in a 2-fold increase in 30S and 50S free ribosomal subunits, whereas the polysome fraction was unaffected. Overproduction of rRNA and "free" ribosomes produced a large repression of rRNA and tRNA synthesis from chromosomal genes and a smaller increase in the concentration of guanosine tetraphosphate. These results lend support to the ribosome feedback regulation model: rRNA and tRNA operons are negatively regulated, either directly or through some intermediate, by free, nontranslating ribosomes.
Gourse
R L
RL
Takebe
Y
Y
Sharrock
R A
RA
Nomura
M
M
D010582:Bacteriophage lambda / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005246:Feedback; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D009876:Operon; D010957:Plasmids; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics*; D012343:RNA, Transfer / Q000096:biosynthesis*; D012270:Ribosomes / Q000378:metabolism*
D012335:RNA, Ribosomal; D006159:Guanosine Tetraphosphate; D012343:RNA, Transfer