Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

micF RNA regulates the levels of outer membrane protein F (OmpF) in Escherichia coli in response to temperature increase and other stress conditions by decreasing the levels of ompF mRNA (Andersen et al., 1989). A 93-nucleotide micF RNA was synthesized in vitro directly from polymerase chain reaction generated DNA which was designed to contain a functional T7 RNA polymerase promoter upstream of the micF RNA gene and an appropriate restriction site for transcription termination. A transcript (150 nucleotides) containing the ribosomal binding domain of ompF mRNA messenger was synthesized in vitro from the ompF gene cloned into a T7 expression vector. A stable duplex was formed between micF RNA and the 150-nucleotide 5' transcript of ompF mRNA after incubation at 37 degrees C in a physiological buffer. The melting curve of the duplex formed by micF RNA and 150-nucleotide transcript revealed a Tm of 56 degrees C and a delta Tm that spans about 20 degrees C; both are consistent with the proposed structure for the micF/ompF duplex. In addition, as determined by competition studies and UV cross-linking/label-transfer analyses, an E. coli protein was found to bind specifically to micF RNA. The protein also bound weakly to the 150-nucleotide ompF transcript. The data are the first to demonstrate the complex between micF RNA and the 5' end of ompF mRNA and suggest that in vivo a micF ribonucleoprotein (RNP) particle may participate in the destabilization ompF mRNA during thermoregulation of OmpF porin.
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PMID:micF RNA binds to the 5' end of ompF mRNA and to a protein from Escherichia coli. 170 97

We analyzed 12 individual codons, which differed widely with respect to the frequency of use in Escherichia coli and the abundance of the corresponding tRNAs, for their influence on the coupling between transcription and translation. This was probed by determining the effects of codon substitutions in the leader peptide gene on transcription past the pyrE attenuator, as described previously by Bonekamp et al. (F. Bonekamp, H. D. Andersen, T. Christensen, and K. F. Jensen, Nucleic Acids Res. 13:4113-4123, 1985). In principle, the results revealed that either RNA polymerase or the (leading) ribosomes pass the different codon strings at different rates. However, under the assumption that the rate of transcription elongation is unaffected by the sequence changes, the results may be interpreted as indicating that different codons are translated at different rates and that these rates do not generally reflect the concentrations of the corresponding tRNAs or the frequencies with which the codons are used in E. coli. Moreover, it seems that codon synonyms that are served by the same isoaccepting tRNA species can deviate as much from each other in translational behavior as synonymous codons that are served by isoacceptors present in the cell in widely different amounts can.
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PMID:Translation rates of individual codons are not correlated with tRNA abundances or with frequencies of utilization in Escherichia coli. 250 20