Two seemingly homologous noncoding RNAs act hierarchically to activate glmS mRNA translation.
Small noncoding RNAs (sRNA) can function as posttranscriptional activators of gene expression to regulate stress responses and metabolism. We here describe the mechanisms by which two sRNAs, GlmY and GlmZ, activate the Escherichia coli glmS mRNA, coding for an essential enzyme in amino-sugar metabolism. The two sRNAs, although being highly similar in sequence and structure, act in a hierarchical manner. GlmZ, together with the RNA chaperone, Hfq, directly activates glmS mRNA translation by an anti-antisense mechanism. In contrast, GlmY acts upstream of GlmZ and positively regulates glmS by antagonizing GlmZ RNA inactivation. We also report the first example, to our knowledge, of mRNA expression being controlled by the poly(A) status of a chromosomally encoded sRNA. We show that in wild-type cells, GlmY RNA is unstable due to 3' end polyadenylation; whereas in an E. coli pcnB mutant defective in RNA polyadenylation, GlmY is stabilized and accumulates, which in turn stabilizes GlmZ and causes GlmS overproduction. Our study reveals hierarchical action of two well-conserved sRNAs in a complex regulatory cascade that controls the glmS mRNA. Similar cascades of noncoding RNA regulators may operate in other organisms.
Urban
Johannes H
JH
Max Planck Institute for Infection Biology, RNA Biology Group, Berlin, Germany.
Vogel
Jörg
J
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D001483:Base Sequence; D004789:Enzyme Activation; D020536:Enzyme Activators; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D026723:Polyadenylation; D011062:Polynucleotide Adenylyltransferase; D014176:Protein Biosynthesis / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000737:chemistry / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing)
D001426:Bacterial Proteins; D020536:Enzyme Activators; D029968:Escherichia coli Proteins; D011062:Polynucleotide Adenylyltransferase; D012329:RNA, Bacterial; D012333:RNA, Messenger; D022661:RNA, Untranslated; C063643:pcnB protein, E coli; C000731191:component S, glutamate mutase protein, Bacteria; D005945:Glutamine-Fructose-6-Phosphate Transaminase (Isomerizing)