Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.3 (RNase III)
 1,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To determine if proteins RNase III and rho, both of which can determine the 3' ends of RNA molecules, can complement each other, double mutants defective in these two factors were constructed. In all cases (four rho mutations tested) the double mutants were viable at lower temperatures, but were unable to grow at higher temperatures at which both of the parental strains grew. Genetic analyses suggested that the combinations of the rnc rho (RNase III-Rho-) mutations was necessary and probably sufficient to confer temperature sensitivity on carrier strains. Physiological studies showed that synthesis and maturation of rRNA, which is greatly affected by RNase III, as well as other RNAs, was indistinguishable in rnc rho strains as compared to rnc rho+ strains, thus suggesting that RNase III and rho do not complement one another in determining the 3' ends of RNA molecules. In rnc rho strains, however, the newly synthesized rRNA failed to accumulate. Thus, decay of rRNA could be the reason for the temperature sensitivity of the double mutant strains. These experiments suggest that RNase III and rho can both protect rRNA from degradation by cellular ribonucleases. They also point to the possibility that the nucleotide sequences involved in the determination of the 3' ends of RNA molecules by these two factors are not identical.
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PMID:Metabolism of ribosomal RNA in mutants of Escherichia coli doubly defective in ribonuclease III and the transcription termination factor rho. 35 8

We have established that the long non-coding intercistronic region of the dicB operon of Escherichia coli expresses a trans-acting division inhibitor specified by a region dicF, at most 65 nucleotides-long. The present study deals with the processing of dicBF operon mRNA in vivo, and identifies the dicF gene product as a 53 nucleotide RNA species. A sequence at the end of DicF resembles, and behaves as, a Rho-independent terminator, but further processing of readthrough transcripts, presumably by RNase III, followed by a limited 3' to 5' degradation, appears to generate additional DicF-RNA 3' ends. For the 5' end of DicF-RNA, our results show that a 190 nucleotide precursor DicF-RNA species is formed by cleavage at an RNase III site, while the 53 nucleotide minimal DicF-RNA is generated by further processing requiring the presence of an active form of RNase E in vivo. These data indicate that an untranslated product derived from an operon RNA can have a regulatory activity by affecting cell division.
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PMID:Escherichia coli cell division inhibitor DicF-RNA of the dicB operon. Evidence for its generation in vivo by transcription termination and by RNase III and RNase E-dependent processing. 169 Dec 99

Two genes, secE and nusG, situated between the tufB and ribosomal protein rplKAJL operons in the rif region at 90 min on the Escherichia coli chromosome, have been sequenced and characterized. The secE gene encodes a 127-amino-acid-long polypeptide, which is an integral membrane protein essential for protein export (P. J. Schatz, P. D. Riggs, A. Jacq, M. J. Fath, and J. Beckwith, Genes Dev. 3:1035-1044, 1989). The nusG gene encodes a 181-amino-acid-long polypeptide and is involved in transcription antitermination. The protein product of nusG is essential for bacterial viability. The secE-nusG genes are cotranscribed, with transcripts initiated at the PEG promoter and terminated at the Rho-independent terminator in the region of the rplK promoter. The majority of transcripts are processed at a number of sites in the 5' untranslated leader region by RNase III and are possibly also processed by a second unidentified nuclease. The role of transcript processing in the regulation of secE and nusG has not yet been established. The juxtaposition and coregulation of a protein export factor and a transcriptional factor raise questions concerning a functional connection between the two processes.
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PMID:Sequence and transcriptional pattern of the essential Escherichia coli secE-nusG operon. 213 19

S1 nuclease mapping was performed on transcripts from the major leftward operon of the bacteriophage lambda in order to locate the 3' ends of stable RNA species produced in vivo. The analysis was carried out on RNA purified from either an induced lambda prophage or bacteria carrying a plasmid containing a large segment of lambda including the intact PL operon through the bet gene. The S1 nuclease mapping was performed on transcripts produced in the presence and the absence of the N antitermination function, and in the presence and the absence of either the RNase III processing enzyme or the Rho factor. The results of this work indicate that the intercistronic region between the N and ral genes of lambda contains three sites at which transcripts end under N-Rho+ conditions (positions on the lambda sequence: 34,826, 34,558 and 34,393). The distal two correspond to the two sites previously described in this region as tL1 (on both sides of the BamHI site). In the region between ral and Ea10, we mapped the 3' ends of three species of RNA. The 3' end of one species was found to be located 90 nucleotides proximal to tL2a, at 34,000 in the lambda sequence. The terminator at this site may be partially N-resistant. In an RNase III deficient host, an additional RNA species is formed. The 3' end of this RNA species is located at tL2a (33,910 on the lambda sequence). In the presence of the antitermination N gene product, the readthrough transcripts are processed to form a 3' end at position 33,980 on the lambda sequence. These results suggest that elongation of transcription of the lambda PL operon is reduced gradually by clusters of termination located between genes and that the expression of the terminated products is further controlled by processing of the mRNA.
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PMID:Transcription termination and processing sites in the bacteriophage lambda pL operon. 302 19

Transcription of T7 DNA by purified Escherichia coli RNA polymerase without added factors produces long RNA molecules that begin near the left end of T7 DNA and terminate at the end of the early region. An endonuclease has been isolated from uninfected E. coli that cleaves these long RNAs at five specific sites to generate RNA molecules essentially the same as the early T7 RNAs observed in vivo. This sizing factor, which may be RNase III, can act during or after RNA synthesis. Synthesis of early RNA chains has been shown to start at three strong initiators, spaced about 150-200 base-pairs apart near the left end of T7 DNA. Thus, the five cleavages by sizing factor generate the five early messenger RNAs of T7 plus three overlapping RNAs from the promoter region. RNA chains that are started at two of the strong initiators begin with A; those started at the third begin with G. A few minor initiators have also been observed, from which only short chains seem to be synthesized. Their locations in T7 DNA have not been mapped. Rho factor does not appear to be needed to generate any of these early T7 RNAs.
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PMID:T7 early RNAs are generated by site-specific cleavages. 457 24

Escherichia coli NusA and NusB proteins bind specific sites, such as those in the leader and spacer sequences that flank the 16S region of the ribosomal RNA transcript, forming a complex with RNA polymerase that suppresses Rho-dependent transcription termination. Although antitermination has long been the accepted role for Nus factors in rRNA synthesis, we propose that another major role for the Nus-modified transcription complex in rrn operons is as an RNA chaperone insuring co-ordination of 16S rRNA folding and RNase III processing that results in production of proper 30S ribosome subunits. This contrarian proposal is based on our studies of nusA and nusB cold-sensitive mutations that have altered translation and at low temperature accumulate 30S subunit precursors. Both phenotypes are suppressed by deletion of RNase III. We argue that these results are consistent with the idea that the nus mutations cause altered rRNA folding that leads to abnormal 30S subunits and slow translation. According to this idea, functional Nus proteins stabilize an RNA loop between their binding sites in the 5' RNA leader and on the transcribing RNA polymerase, providing a topological constraint on the RNA that aids normal rRNA folding and processing.
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PMID:Nus transcription elongation factors and RNase III modulate small ribosome subunit biogenesis in Escherichia coli. 2319 53

Dynamic control is a distinguished strategy in modern metabolic engineering, in which inducible convergent transcription is an attractive approach for conditional gene silencing. Instead of a simple strong "reverse" (r-) promoter, a three-component actuator has been developed for constitutive genes silencing. These actuators, consisting of r-promoters with different strengths, the ribosomal transcription antitermination-inducing sequence rrnG-AT, and the RNase III processing site, were inserted into the 3'-UTR of three E. coli metabolic genes. Second and third actuator components were important to improve the effectiveness and robustness of the approach. The maximal silencing folds achieved for gltA, pgi, and ppc were approximately 7, 11, and >100, respectively. Data were analyzed using a simple model that considered RNA polymerase (RNAP) head-on collisions as the unique reason for gene silencing and continued transcription after collision with only one of two molecules. It was previously established that forward (f-) RNAP with a trailing ribosome was approximately 13-times more likely to continue transcription after head-on collision than untrailed r-RNAP which is sensitive to Rho-dependent transcription termination (RhoTT). According to the current results, this bias in complex stabilities decreased to no more than (3.0-5.7)-fold if r-RNAP became resistant to RhoTT. Therefore, the developed constitutive actuator could be considered as an improved tool for controlled gene expression mainly due to the transfer of r-transcription into a state that is resistant to potential termination and used as the basis for the design of tightly regulated actuators for the achievement of conditional silencing.
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PMID:Universal Actuator for Efficient Silencing of Escherichia coli Genes Based on Convergent Transcription Resistant to Rho-Dependent Termination. 3244 68