Regulation of the Escherichia coli uncH gene by mRNA secondary structure and translational coupling.
The uncH gene is one of the most poorly-expressed genes of the proton-translocating ATPase (unc) operon of Escherichia coli. We constructed in-frame lacZ fusions to uncH and used site-directed mutagenesis to decrease the stability of the putative mRNA secondary structure in the Shine and Dalgarno region for this gene. These mutations significantly increased the expression of uncH. We also used the unc-lac fusions to show that the insertion of stop codons and a frameshift mutation in uncF, the gene preceding uncH, caused a 10-fold reduction in uncH expression. Hybridization of total cellular RNA with a lacZ-specific probe indicated that transcriptional polarity could not account for the observed decrease in gene expression. These results demonstrate that uncH expression is controlled by mRNA sequences around the translational initiation region, and is translationally coupled to uncF, even in cases where the putative mRNA secondary structure is weakened or eliminated.
D001426:Bacterial Proteins / Q000235:genetics*; D025243:Bacterial Proton-Translocating ATPases; D001483:Base Sequence; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006860:Hydrogen Bonding; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009876:Operon; D014176:Protein Biosynthesis; D006180:Proton-Translocating ATPases / Q000235:genetics*; D012329:RNA, Bacterial / Q000235:genetics / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics / Q000648:ultrastructure
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; C074430:uncF protein, E coli; D025243:Bacterial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; C101709:AtpH protein, E coli