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)

The transducing phages lambdadaroE and lambdadilv5, which carry the Escherichia coli ribosomal RNA operons rrnD and rrnX, respectively, have been mapped with the restriction endonucleases BamHI, EcoRI, HindIII, and Sma I. Using hybridization techniques, we have located the ribosomal RNA genes on these phage DNAs. The DNA sequence of the 437-base-pair 16 S-23 S ribosomal RNA intergenic spacer in the two rRNA operons rrnD and rrnX has been determined. The nucleotides examined exhibit only one base pair change between rrnD and rrnX. Both spacer regions contain the genes for tRNA1Ile and tRNA1BAla; the gene sequences are identical with the previously deduced tRNA sequences and are clustered within the first 60% of the spacer DNA. The most striking feature of the 16 S-23 S intergenic region in these two operons is the disparity in G-C content between the tRNA gene sequences (60% G-C) and the remaining spacer DNA (37% G-C). Spacer sequences are known to be involved in the processing of the ribosomal RNA transcript by RNase III and RNase P. In addition, we report the sequence of the first 108 base pairs of the 23 S rRNA gene.
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PMID:Sequence of the 16 S-23 s spacer region in two ribosomal RNA operons of Escherichia coli. 37 88

[3H]Uracil-pulse-labeled RNA from Escherichia coli infected with f1 bacteriophage was fractionated on polyacrylamide gels containing urea. Eight phage-specific RNA species were present with approximate lengths ranging from 2100 to 400 nucleotides. The amount of the seven largest species was increased when the infected bacteria were incubated at 41 degrees C. When the RNA was isolated and used as message in an in vitro protein-synthesizing system, most of the RNA species appeared to direct the synthesis of the phage gene VIII protein. The six largest species also directed the synthesis of the phage gene V protein. Some of the labeled smaller RNA species increased in amount after addition to rifampicin, suggesting that they may have resulted from cleavage of larger RNA species. These particular smaller RNA species also were present in infected bacteria containing a mutant RNase III. The data are discussed in terms of the regulation of synthesis of the phage-specific proteins.
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PMID:Bacteriophage f1 infection of Escherichia coli: identification and possible processing of f1-specific mRNAs in vivo. 37 28

An in vitro replication system has been used to study the control of DNA replication of the relaxed plasmids Col E1 and RSF1030. An RNA transcript approximately 100 nucleotides long is synthesized during the in vitro DNA replication reaction. This RNA is synthesized approximately 450 bp away from the origin of replication. A small insertion in the coding sequence for the RNA made from Col E1 DNA leads to a larger RNA species and simultaneously to an increase in plasmid copy number. Revertants missing the specific insertion show shorter RNA transcripts and wild-type copy number. Although plasmids Col E1 and RSF1030 have no extensive sequence homology, the RNA synthesized during RSF1030 replication has almost the same mobility as the Col E1 RNA on polyacrylamide gels and hybridizes to the Col E1 origin region. Extracts prepared from mutants of Escherichia coli deficient in ribonuclease III do not replicate RSF1030 or Col E1 plasmids in vitro. When supplemented with homogeneous RNAase III, such extracts do support DNA replication on these templates, indicating that RNAase III is required for DNA replication. We propose that the 100 nucleotide RNA species is involved in regulating the initiation of DNA replication of these plasmids, and that RNAase III may be involved in processing this RNA.
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PMID:Role of plasmid-coded RNA and ribonuclease III in plasmid DNA replication. 38 34

The 5'-terminal sequences of Escherichia coli ribosomal RNA precursors (pre-rRNAs) synthesized in vivo were characterized by RNA oligonucleotide sequence analysis. The 60- to 170-nucleotide-long 5'-end-specific fragments were produced by RNase III treatment of 30S and 18S pre-rRNAs. Comparison of the RNA oligonucleotides of these fragments with known DNA sequences of the promoter regions of several ribosomal RNA operons allows us to determine the start points of transcription of each operon. We conclude that transcription of most (and perhaps all) rRNA operons is initiated in vivo at two tandem promoters, called P1 and P2, which have recently been identified by in vitro transcription studies of several groups. Depending on the transcription unit, the initiating nucleotide at P1 promoters is either ATP or GTP, whereas at P2 promoters it is either CTP or GTP.
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PMID:Initiation of Escherichia coli ribosomal RNA synthesis in vivo. 39 3

Heterogeneous nuclear RNA (hnRNA) from HeLa cells contains intramolecular duplexes. Since hnRNA is associated with protein in vivo, it is possible that the double-stranded regions observed in deproteinized hnRNA form spontaneously upon the release of protein from single-stranded but potentially complementary sequences. We show here that this is not the case for a class of double-stranded sequences that is defined by resistance to RNases A + T(1) at high ionic strength. Exposure of HeLa hnRNA.ribonucleoprotein (hnRNP) particles to Escherichia coli RNase III, a double-strand-specific endoribonuclease, destroys most of the sequences resistant to RNases A + T(1). This effect is completely blocked when hnRNP is exposed to RNase III in the presence of an excess of purified double-stranded RNA. In addition, we show that there exist two classes of double-stranded RNA in hnRNP at a salt concentration of 0.13 M. These are distinguished by their relative resistance to RNases A + T(1). The more stable double-stranded sequences, which are resistant to RNases A + T(1) at 0.13 M, comprise 1.0-1.1% of the nucleotides in hnRNP. The less stable double-stranded sequences comprise an additional 1.5-2.0% of the nucleotides in hnRNP. These are sensitive to RNase III at 0.13 M, but are not resistant to RNases A + T(1) unless the salt concentration is raised to 0.63 M. The demonstration that double-stranded sequences resistant to RNases A + T(1) exist in native ribonucleoprotein and are not artifacts of deproteinization now makes it appropriate to seriously consider their possible functional role in hnRNA metabolism, perhaps as binding sites for regulatory proteins involved in mRNA processing.
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PMID:Secondary structure of heterogeneous nuclear RNA: two classes of double-stranded RNA in native ribonucleoprotein. 41 25

Nucleoli of both chick embryos and mouse Ehrlich ascites cells contain an enzymatic activity that is very similar to RNase DII, an enzyme isolated from total chick embryos for its ability to degrade double-stranded RNA. The enzyme can be extracted by low salt/EDTA from nucleoli and is associated with pre-ribosomal 80-S and 55-S particles. Under ionic conditions which are inhibitory for the nucleolytic activity the transcript in vitro of nucleoli is not processed and sediments around 45 S. Under salt conditions which are optimal for the nucleolar enzyme the nucleolar transcripts are cleaved to distinct intermediate-sized molecules. Addition of the chicken RNase DII or RNase III to the nucleolar transcription system results in a similar shift of the chain length of the RNA molecules. It is concluded that a nucleolar RNase recognizing double-stranded regions in the pre-ribosomal RNA is involved in the maturation of ribosomal RNA.
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PMID:Localisation of an endonuclease specific for double-stranded RNA within the nucleolus and its implication in processing ribosomal transcripts. 42 96

The DNA sequence of the fragment Hind.30, 378 bases long, from the beginning of gene 1 of T7 is presented. It contains the C promoter, two in vitro transcriptional terminator sites and a sequence of 171 bases which probably codes for the N terminus of the T7 RNA polymerase. The sequence also codes for the RNase III cleavage site before gene 1. The overlaps with the transcriptional terminators, The RNA transcript of the sequence about the terminators can be arranged in a set of alternative double-stranded hairpin structures. It is suggested that conversion between these structures may have a role in termination; this may be influenced by interactions with ribosomes and RNase III. The region of the C promoter between genes 0.7 and 1 thus contains several sites which may be involved in the control of transcription and translation.
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PMID:Control sites in the sequence at the beginning of T7 gene 1. 49 11

45S ribosomal precursor RNA and large heterogeneous RNA molecules (greater than 45S) extracted from human leukemic cells were incubated in vitro with purified RNase III, which specifically attacks double-helical RNA regions. About 50% of the ribosomal precursor was cleaved into two major fragments sedimenting at 28S and 32S respectively. A limited number of cleavages was also introduced in about 40% of heterogeneous RNA molecules sedimenting faster than 45S, causing a partial 'shift' to a polydisperse distribution in the 10S-45S range.
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PMID:In vitrocleavage of 45S pre-ribosomal RNA and of giant heterogeneous RNA extracted from human leukemic cells. 59 70

T7 early mRNA's are generated from a high-molecular-weight precursor RNA by site-specific RNase III cleavage. When T7 DNA is transcribed in vitro by Escherichia coli RNA polymerase, the transcript is a large, single-piece RNA equivalent to the in vivo precursor RNA. The T7 RNA synthesized in vitro can be translated as a polycistronic messenger without cleavage by RNase III. All T7 early proteins are synthesized in an RNase III-free, protein-synthesizing system directed by the uncleaved T7 RNA.
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PMID:Translation of T7 RNA in vitro without cleavage by RNase III. 77 30

1. New high molecular weight RNA species have been found in an RNase III deficient mutant of E. coli. These RNA's were very minor but stable components of the cells, and their molecular weights, which range from 3-5.5 million daltons, are higher than that of 30S precursor ribosomal RNA. In these respects these RNAs are similar to the 2.5 M RNA reported previously (Yuki and Wittmann, 1974). 2. A method to analyse minor RNA components is described. A linear relationship between logarithms of molecular weights and logarithms of distance moved in 1.5-7.5% polyacrylamide concentration gradient gels is also described in this report. 3. DNA species whose molecular weights ranged from 1.8 to 5.5 million daltons and also a species of 8 million daltons are described. two techniques commonly used to identify RNA, viz. DNase treatment and labeling with radioactive uridine, are discussed in connection with these DNAs. 4. The determination of the molecular weight of 30S precursor ribosomal RNA is discussed and it is suggested that this RNA is heterogenous, consisting of two species of molecular weight 1.8 million daltons and 2.0 million daltons, respectively.
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PMID:Detection of ribonucleic acids which are larger than 30S precursor ribosomal RNA in RNase III deficient E. coli cells. 77 88


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