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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 cIII gene product of lambdoid bacteriophages promotes lysogeny by stabilizing the phage-encoded CII protein, a transcriptional activator of the repressor and integrase genes. Previous works showed that the synthesis of the bacteriophage lambda CIII protein has specific translational requirements imposed by the structure of the mRNA. To gain insight into the mRNA structure and its role in regulating cIII translation, we undertook a mutational analysis of the cIII gene of the related bacteriophage HK022. Our data support the hypothesis that in HK022, as in lambda, translation initiation requires a specific mRNA structure. In addition, we found that translation of HK022 cIII, like that of lambda, is strongly reduced in a host deficient in the endonuclease RNase III.
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PMID:Genetic analysis of the cIII gene of bacteriophage HK022. 182 68

The gene encoding the Neurospora mitochondrial large rRNA contains a single group I intron of 2.3 kilobases that is not self-splicing in vitro. We showed previously that the splicing of this intron in vivo and in vitro is dependent on the Neurospora cyt-18 protein, mitochondrial tyrosyl-tRNA synthetase. In the present work, we carried out further structural analysis of the intron and constructed mutant derivatives of it in order to identify features that are either required for splicing or prevent it from self-splicing. Previous studies showed that the intron contains a large hairpin structure near the 5' splice site. By mapping RNase III cleavage sites, we identified this hairpin structure as an extended P2 stem. We construct a mini-intron of 388 nucleotides by deleting the 426-amino acid intron open reading frame, most of the 5' intron hairpin, and all of L8. This mini-intron shows the same protein-dependent splicing as the full length intron, but is still not self-splicing. Further deletions, which remove all of P2 or all or part of P4, P6, P7, or P9, inactivate splicing, suggesting that an intact group I intron core structure is required. Strengthening the P1, P10, or P9.0 pairings did not enable the mini-intron to self-splice. Our findings indicate that the inability of the mitochondrial large rRNA intron to self-splice reflects deficiency of a structure or activity required for cleavage at the 5' splice site, either in the intron core itself or in the interaction between the core and the P1 stem.
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PMID:Structural analysis of the Neurospora mitochondrial large rRNA intron and construction of a mini-intron that shows protein-dependent splicing. 182 45

Cells overexpressing the RNA-processing enzymes RNase III, RNase E and RNase P were fractionated into membrane and cytoplasm. The RNA-processing enzymes were associated with the membrane fraction. The membrane was further separated to inner and outer membrane and the three RNA-processing enzymes were found in the inner membrane fraction. By assaying for these enzymatic activities we showed that even in a normal wild-type strain of Escherichia coli these enzymes fractionate primarily with the membrane. The RNA part of RNase P is found in the cytosolic fraction of cells overexpressing this RNA, while the overexpressed RNase P protein sediments with the membrane fraction; this suggests that the RNase P protein anchors the RNA catalytic moiety of the enzyme to a larger entity. The implications of these findings for the cellular organization of the RNA-processing enzymes in the cell are discussed.
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PMID:Location of the RNA-processing enzymes RNase III, RNase E and RNase P in the Escherichia coli cell. 194 11

The Schizosaccharomyces pombe pac1 gene is a multicopy suppressor of the pat1 temperature-sensitive mutation, which directs uncontrolled meiosis at the restrictive temperature. Overexpression of the pac1 gene had no apparent effect on vegetative growth but inhibited mating and sporulation in wild type S. pombe cells. In such cells, expression of certain genes required for mating or meiosis was inhibited. The pac1 gene is essential for vegetative cell growth. The deduced pac1 gene product has 363 amino acids. Its C-terminal 230 residues revealed 25% amino acid identity with ribonuclease III, an enzyme that digests double-stranded RNA and is involved in processing ribosomal RNA precursors and certain mRNAs in Escherichia coli. The pac1 gene product could degrade double-stranded RNA in vitro. These observations establish the presence of a RNase III homolog in eukaryotic cells. The pac1 gene product probably inhibits mating and meiosis by degrading a specific mRNA(s) required for sexual development. It is likely that mRNA processing is involved in the regulation of sexual development in fission yeast.
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PMID:S. pombe pac1+, whose overexpression inhibits sexual development, encodes a ribonuclease III-like RNase. 198 84

The chromosome of the bacterial virus, BA14, a member of the T7 lytic coliphage group, was characterized by direct measurement of its length and construction of a restriction map. The chromosome (39.6 kb) is essentially the same size as T7 (39.9 kb), is devoid of a large number of restriction sites expected for a DNA of this size, and moreover, lacks modification sites for the Escherichia coli Dam and Dcm methyltransferases. The BA14 early region was assigned by testing the ability of specific chromosomal restriction fragments to direct RNA synthesis by E. coli RNA polymerase, and analysis of in vitro RNase III cleavage products of the transcripts. The data support and extend the previous assertion that BA14 is a representative of a distinct T7 subgroup, and limited nucleotide sequence analysis of the BA14 DNA ligase-encoding gene suggests a closer relationship of BA14 to T7 than to T3 phage, another member of the T7 group.
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PMID:Physical map and genetic early region of the T7-related coliphage, BA14. 201 14

Using lambda phage clones containing segments of the Escherichia coli K12 chromosome as hybridization probes, we found one gene at 42 min on the E. coli chromosome map, the expression of which was affected by RNase III. The sequence of the DNA fragment containing this gene (gen-165) revealed the presence of an open reading frame encoding a polypeptide of 165 amino acid residues. The amino acid sequence deduced from the nucleotide sequence exhibited a remarkable similarity to that of the human ferritin H chain.
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PMID:Cloning and sequencing of an Escherichia coli K12 gene which encodes a polypeptide having similarity to the human ferritin H subunit. 201 45

The primary transcripts of the rpsO-pnp, rnc-era-recO and metY-nusA-infB operons of E coli are each processed by RNase III, upstream of the first translated gene, in hair-pin structures formed by the 5' non-coding leader. The mRNAs of the 3 operons, of which the 5' terminal motifs have been removed by RNase III, decay significantly more rapidly than the uncut transcripts which accumulate in the RNase III deficient strain. The rapid decay of a primary transcript of the metY-nusA-infB operon, initiated at a secondary promoter in the vicinity of the RNase III sites, suggests that the 5' features upstream of the RNase III cutting sites are responsible for the stability of the uncut RNAs. RNase III autocontrols its own expression by removing the 5' motif which stabilizes its mRNA. Similarly, the synthesis of polynucleotide phosphorylase and of protein Era are also controlled by RNase III cleavages which trigger the degradation of their messengers. The role of RNase III in the regulation of gene expression and the possible mechanisms of mRNA stabilization and of 5' to 3' decay initiated by RNase III processing are discussed.
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PMID:RNase III cleavages in non-coding leaders of Escherichia coli transcripts control mRNA stability and genetic expression. 208 45

The synthesis rates of ribonuclease III (RNase III) and Era proteins are relatively low, and expression of the era gene is translationally coupled with expression of the rnc gene. Expression of both genes is negatively controlled by RNase III itself. We have constructed plasmids that overproduce RNase III and/or Era proteins under the control of the lambda PL promoter. A plasmid with the rnc gene under PL control expresses RNase III at levels greater than 40% of total cellular protein. Another plasmid with the era gene under PL control and a modified translation-initiation signal produces up to 80% of total cell protein as Era. Each protein has been purified using simple and rapid procedures. Purified RNase III protein specifically processes mRNA transcripts containing known RNase III sites. The purified Era protein binds GDP and GTP and has GTPase activity. Kinetic analysis shows that one molecule of GTP or GDP is bound/Era peptide with a Kd of 5.5 microM for GTP binding and 1.0 microM for GDP binding. The Km of the Era GTPase is 9.0 microM, and the maximum catalyzed rate of GTP hydrolyzed/min/mol of Era protein at 37 degrees C is 9.8 mmol.
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PMID:Expression and characterization of RNase III and Era proteins. Products of the rnc operon of Escherichia coli. 210 34

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

The 77-nucleotide OOP antisense RNA of bacteriophage lambda complements lambda cII-O mRNA in a region that includes 55 nucleotides at the 3' end of the cII gene and 22 nucleotides in the intercistronic region between the cII and O genes. OOP RNA, produced from multicopy plasmids, inhibits lambda cII gene expression by approximately 100-fold through an RNase III-dependent mechanism. Using primer extension analysis of cellular RNA isolated from an induced lambda lysogen that contains an OOP DNA plasmid, we have identified a cleavage site in cII-O mRNA within the region of complementarity with OOP RNA, at 13 nucleotides from the 3' end of that region. Ribonuclease protection experiments demonstrate that almost all cII-O mRNA in this overlap region is cleaved when OOP RNA is overproduced in RNase III+ cells but not in RNase III- cells. RNA fragments are detected that extend into the O gene from the cleavage sites, while the sister fragments that extend into the cII gene cannot be detected and must be eliminated by additional hydrolytic events. Differences in levels of uncleaved mRNA between RNase III+ and RNase III- cells are much less at several hundred nucleotides to either side of the target region. An alternate OOP RNA-dependent hydrolytic process occurs in RNase III- cells that results in cleavages in one of two regions, one close to the cleavage site observed in RNase III+ cells, and the second several nucleotides beyond the end of the complementary region between OOP RNA and cII-O mRNA. In this latter case, the fragments that extend into the cII gene are stable, while the sister O gene fragments are destroyed, in direct contrast to the RNase III-dependent process.
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PMID:RNase III-dependent hydrolysis of lambda cII-O gene mRNA mediated by lambda OOP antisense RNA. 214 37


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