Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.27.1 (RNase)
16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific cleavage of mRNAs by RNase III has been shown to control the expression of several Escherichia coli genes. We show here that the expression of gene 19 of the conjugative resistance plasmid R1 is controlled in its expression by the same endoribonuclease. In vivo studies revealed that a DNA fragment of 150 nucleotides including a perfect 22 nucleotide inverted repeat in the gene 19 coding region is responsible for the low expression of the gene both at the protein and the RNA levels. By using a translational gene 19-lacZ fusion in isogenic RNase III+ and RNase III- strains we could identify RNase III as the key element in the down-regulation of gene 19 expression. The sequencing of in vitro generated and RNase III-digested transcripts confirmed the in vivo studies and revealed the exact positions of the RNase III cleavage sites within the coding part of the gene 19 transcript. The in vitro determined RNase III cleavage of gene 19 mRNA was confirmed by in vivo primer extension analysis. Finally, we could show that an exchange of three nucleotides within the RNase III recognition site abolished RNase III cleavage in vitro.
...
PMID:Expression of gene 19 of the conjugative plasmid R1 is controlled by RNase III. 769 35

The complex amiB-mutL-miaA-hfq-hflX-hflK-hflC superoperon of E coli contains important genes for several fundamental cellular processes, including cell-wall hydrolysis (amiB), DNA repair (mutL), tRNA modification (miaA) and proteolysis (hflX-hflK-hflC). We report here the transcriptional pattern and possible posttranscriptional regulation of mutL, miaA and hfq genes of this superoperon. RNase protection analysis of mRNA transcribed from the bacterial chromosome demonstrated that there is co-transcription of mutL and miaA. In addition, two internal promoters, PmiaA and P1hfq were identified and mapped to 201 and 837 nucleotides upstream from the respective translation start sites. PmiaA contains poor matches to the -10 and -35 regions of the sigma-70 RNA polymerase consensus sequences, but it contains multiple potential Fis-binding sites and an upstream AT-rich region with poly(A) sequences. The basic arrangement of Fis-binding sites followed by an AT rich region is shared with promoters for rRNA operons and some of the tRNA and tRNA modification genes. As part of an initial study of mutL and miaA regulation, we measured transcript amounts in isogenic rne, rnc and rne rnc double mutants which are deficient in RNase E, RNase III or both. The amounts of steady state level mutL-miaA cotranscript, PmiaA transcript and P1hfq transcript increased eight-, nine- and three-fold respectively in an rne3071 mutant when compared to the rne+ parent. In contrast, amounts of the three transcripts were the same in an rnc105 mutant and its rnc+ parent. These results indicate that mutL, miaA, and hfq expression could be regulated by multiple mechanisms, including degree of cotranscription from upstream genes, modulation of internal promoter strength, and by RNase E activity. A model is presented for RNase E-mediated posttranscriptional regulation that may coordinate mutL expression with replication and miaA with tRNA amounts under different growth conditions, especially during nutrient upshifts.
...
PMID:Transcriptional patterns of the mutL-miaA superoperon of Escherichia coli K-12 suggest a model for posttranscriptional regulation. 774 52

The unusual longevity of the Escherichia coli ompA transcript is determined by its 5' untranslated region (UTR), which functions in vivo as an mRNA stabilizer. Here we show that this 5' UTR can prolong the lifetime in E. coli of a variety of heterologous mRNAs to which it is joined, either as a gene fusion or as an operon fusion. Statistical extrapolation suggests that it is quite likely that most E. coli mRNAs could be stabilized in this manner. We conclude that the ompA 5' UTR impedes a major pathway for mRNA degradation in E. coli and that stabilization by fusion to this UTR does not require translational readthrough of the heterologous mRNA segment by ribosomes that initiate translation at the ompA ribosome-binding site. Additional experiments indicate that the E. coli ribonuclease whose action is slowed by the ompA 5' UTR is not RNase III.
...
PMID:The ompA 5' untranslated region impedes a major pathway for mRNA degradation in Escherichia coli. 805 23

Plastid 70S ribosomes were prepared from heterotrophic cultured cells of tobacco (Nicotiana tabacum, BY2), and the 5' termini of the 16S rRNA molecules present in the ribosomes were analyzed. RNase protection and primer extension experiments showed that a minor fraction of the 16S rRNA species carries a leader sequence of 30 nucleotides, coinciding with a putative RNase III cleavage site. The results suggest that an RNase III-like activity is present in plastids and that ultimate 5' maturation of 16S rRNA takes place within the ribosome.
...
PMID:The existence of pre-mature 16S rRNA species in plastid ribosomes. 833 92

RNase III is an endonuclease involved in processing both rRNA and certain mRNAs. To help determine whether RNase III (rnc) is required for general mRNA turnover in Escherichia coli, we have created a deletion-insertion mutation (delta rnc-38) in the structural gene. In addition, a series of multiple mutant strains containing deficiencies in RNase II (rnb-500), polynucleotide phosphorylase (pnp-7 or pnp-200), RNase E (rne-1 or rne-3071), and RNase III (delta rnc-38) were constructed. The delta rnc-38 single mutant was viable and led to the accumulation of 30S rRNA precursors, as has been previously observed with the rnc-105 allele (P. Gegenheimer, N. Watson, and D. Apirion, J. Biol. Chem. 252:3064-3073, 1977). In the multiple mutant strains, the presence of the delta rnc-38 allele resulted in the more rapid decay of pulse-labeled RNA but did not suppress conditional lethality, suggesting that the lethality associated with altered mRNA turnover may be due to the stabilization of specific mRNAs. In addition, these results indicate that RNase III is probably not required for general mRNA decay. Of particular interest was the observation that the delta rnc-38 rne-1 double mutant did not accumulate 30S rRNA precursors at 30 degrees C, while the delta rnc-38 rne-3071 double mutant did. Possible explanations of these results are discussed.
...
PMID:Analysis of mRNA decay and rRNA processing in Escherichia coli multiple mutants carrying a deletion in RNase III. 841 98

The rpsO monocistronic messenger, encoding ribosomal protein S15, is destabilized upon polyadenylation occurring at the hairpin structure of the transcription terminator t1. We report that mRNA fragments differing from the monocistronic transcript by their 3' termini are also polyadenylated in the absence of polynucleotide phosphorylase and RNase II. Some of these 3' extremities result from endonucleolytic cleavages by RNase E and RNase III and from exonucleolytic degradation. Most of these mRNA fragments are destabilized upon polyadenylation with the exception of the RNA species generated by RNase III. RNase E appears to reduce the amount of poly(A) added at the transcription terminator t1.
...
PMID:The rpsO mRNA of Escherichia coli is polyadenylated at multiple sites resulting from endonucleolytic processing and exonucleolytic degradation. 867 Aug 15

The pac1+ gene of the fission yeast Schizosaccharomyces pombe is essential for viability and its overexpression induces sterility and suppresses mutations in the pat1+ and snm1+ genes. The pac1+ gene encodes a protein that is structurally similar to RNase III from Escherichia coli, but its normal function is unknown. We report here the purification and characterization of the Pac1 protein after overexpression in E. coli. The purified protein is a highly active, double-strand-specific endoribonuclease that converts long double-stranded RNAs into short oligonucleotides and also cleaves a small hairpin RNA substrate. The Pac1 RNase is inhibited by a variety of double- and single-stranded polynucleotides, but polycytidylic acid greatly enhances activity and also promotes cleavage specificity. The Pac1 RNase produces 5'-phosphate termini and requires Mg2+; Mn2+ supports activity but causes a loss of cleavage specificity. Optimal activity was obtained at pH 8.5, at low ionic strength, in the presence of a reducing agent. The enzyme is relatively insensitive to N-ethylmaleimide but is strongly inhibited by ethidium bromide and vanadyl ribonucleoside complexes. The properties of the Pac1 RNase support the hypothesis that it is a eukaryotic homolog of RNase III.
...
PMID:Purification and characterization of the Pac1 ribonuclease of Schizosaccharomyces pombe. 871 May 10

The degradation process of the rpsO mRNA is one of the best characterised in E coli. Two independent degradation pathways have been identified. The first one is initiated by an RNase E endonucleolytic cleavage which allows access to the transcript by polynucleotide phosphorylase and RNase II. Cleavage by RNase E gives rise to an rpsO message lacking the stabilising hairpin of the primary transcript; this truncated mRNA is then degraded exonucleolytically from its 3' terminus. This pathway might be coupled to the translation of the message. The second pathway allows degradation of polyadenylated rpsO mRNA independently of RNase II, PNPase and RNase E. The ribonucleases responsible for degradation of poly(A) mRNAs under these conditions are not known. Poly(A) tails have been proposed to facilitate the degradation of structured RNA by polynucleotide phosphorylase. In contrast, we believe that removal of poly(A) by RNase II stabilises the rpsO mRNA harbouring a 3' hairpin. In addition to these two pathways, we have identified endonucleolytic cleavages which occur only in strains deficient for both RNase E and RNase III suggesting that these two endonucleases protect the 5' leader of the mRNA from the attack of unidentified ribonuclease(s). Looping of the rpsO mRNA might explain how RNase E bound at the 5' end can cleave at a site located just upstream the hairpin of the transcription terminator.
...
PMID:Multiple degradation pathways of the rpsO mRNA of Escherichia coli. RNase E interacts with the 5' and 3' extremities of the primary transcript. 891 31

Control of RNA turnover is a major, but poorly understood, aspect of gene regulation. In multicellular organisms, progress toward dissecting RNA turnover pathways has been made by defining some cis-acting sequences that function as either regulatory or cleavage targets (J. G. Belasco and G. Brawerman, Control of Messenger RNA Stability, 1993). However, the identification of genes encoding proteins that regulate or cleave target RNAs has been elusive (C. A. Beelman and R. Parker, Cell 81:79-183, 1995); this gap in knowledge has made it difficult to identify additional components of RNA turnover pathways. We have utilized a modified expression cloning strategy to identify a developmentally regulated gene from Drosophila melanogaster that encodes a RNase that we refer to as Clipper (CLP). Significant sequence matches to open reading frames encoding unknown functions identified from the Caenorhabditis elegans and Saccharomyces cerevisiae genome sequencing projects suggest that all three proteins are members of a new protein family conserved from lower eukaryotes to invertebrates. We demonstrate that a member of this new protein family specifically cleaves RNA hairpins and that this activity resides in a region containing five copies of a previously uncharacterized CCCH zinc finger motif. CLP's endoribonucleolytic activity is distinct from that associated with RNase A (P. Blackburn and S. Moore, p. 317-433, in P. D. Boyer, ed., The Enzymes, vol. XV, part B, 1982) and is unrelated to RNase III processing of rRNAs and tRNAs (J. G. Belasco and G. Brawerman, Control of Messenger RNA Stability, 1993, and S. A. Elela, H. Igel, and M. Ares, Cell 85:115-124, 1995). Our results suggest that CLP may function directly in RNA metabolism.
...
PMID:Cleavage of RNA hairpins mediated by a developmentally regulated CCCH zinc finger protein. 894 20

The Escherichia coli rnc-era-recO operon encodes ribonuclease III (RNase III; a dsRNA endonuclease involved in rRNA and mRNA processing and decay), Era (an essential G-protein of unknown functions and RecO (involved in the RecF homologous recombination pathway). Expression of the rnc and era genes is negatively autoregulated: RNase III cleaves the rncO 'operator' in the untranslated leader, destabilizing the operon mRNA. As part of a larger effort to understand RNase III and Era structure and function, we characterized rnc operon structure, function and regulation in the closely related bacterium Salmonella typhimurium. Construction of a S typhimurium strain conditionally defective for RNase III and Era expression showed that Era is essential for cell growth. This mutant strain also enabled selection of recombinant clones containing the intact S typhimurium rnc-era-recO operon, whose nucleotide sequence, predicted protein sequence, and predicted rncO RNA secondary structure were all highly conserved with those of E coli. Furthermore, genetic and biochemical analysis revealed that S typhimurium rnc gene expression is negatively autoregulated by a mechanism very similar or identical to that in E coli, and that the cleavage specificities of RNase IIIs.t. and RNase IIIE.c. are indistinguishable with regard to rncO cleavage and S typhimurium 23S rRNA fragmentation in vivo.
...
PMID:Structure and regulation of the Salmonella typhimurium rnc-era-recO operon. 915 Aug 81


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---