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 aphid Schizaphis graminum is dependent on an association with a prokaryotic endosymbiont (Buchnera aphidicola). The nucleotide (nt) sequence of a 5040 base pair (bp) DNA fragment of B. aphidicola, homologous to the rplL-rpoB-rpoC portion of the Escherichia coli beta operon, was determined. The DNA coded for the terminal 35 amino acids of RplL (large ribosomal subunit protein L7/L12), the complete RpoB (beta-subunit of RNA polymerase), and the first 209 amino acids of RpoC (beta'-subunit of RNA polymerase). The deduced sequences of B. aphidicola RplL, RpoB, and RpoC were 71, 84, and 91% identical, respectively, to the homologous proteins of E. coli. The sequences of two portions of the intergenic region between rplL and rpoB were nearly identical in both B. aphidicola and E. coli. One sequence constituted an inverted repeat that could be an RNase III-messenger RNA processing site; the other sequence preceded RpoB. A compilation of the codon usage for RpoB, RpoC, and other B. aphidicola proteins indicated a major preference for A or T in the first and third positions, a result consistent with the low guanine plus cytosine (G + C) content of the DNA of this organism.
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PMID:Sequence analysis of an aphid endosymbiont DNA fragment containing rpoB (beta-subunit of RNA polymerase) and portions of rplL and rpoC. 136 99

Transcripts from the rplKAJL-rpoBC ribosomal protein-RNA polymerase gene cluster have been quantified and their ends mapped using RNA-DNA hybridization, sucrose density-gradient sedimentation, Northern hybridization and S1 nuclease protection. The results indicate that the most abundant transcript is the 2600 nucleotide tetracistronic L11-L1-L10-L12 mRNA initiated at the upstream major PL11 promoter and terminated at the transcription attenuator in the L12-beta intergenic space. Somewhat less abundant 1300 nucleotide L11-L1 and L10-L12 bicistronic transcripts were observed. The 3' ends of the L11-L1 transcripts were heterogeneous; most of the ends were localized to three sites within a 110 base-pair region in the L1-L10 intergenic space. This intergenic space encodes also the major PL10 promoter and the mRNA binding site for the L10 translational control protein. Two 5' ends were observed for L10-L12 bicistronic mRNA, one at the PL10 promoter and the other 150 nucleotides further downstream in a region in which promoter activity has not been detected. It is suggested that this second downstream 5' end is generated by processing of the transcripts initiated at the major PL10 promoter. No transcript initiation in the L10-L12 intergenic space was detected. About 80% of the transcripts reading through the L12 gene were terminated in the vicinity of the transcription attenuator that is responsible for the reduction in the expression of the downstream RNA polymerase genes. Transcripts reading through the attenuator were partially processed by RNase III within a potential hairpin structure in the RNA transcript. Processing appears to produce 3' and 5' transcript end sites separated by about ten nucleotides. No other major 5' ends were observed in the L12-beta intergenic space. These results indicate that the two major promoters, PL11 and PL10, are both utilized to drive the interrelated transcriptional expression of this ribosomal protein-RNA polymerase gene cluster.
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PMID:Transcription products from the rplKAJL-rpoBC gene cluster. 244 6

The 319 nucleotide long intergenic region between the rplL (L12) and the rpoB (beta) genes of the L10 operon contains a transcription attenuation sequence and a RNase III mRNA processing sequence. Four site specific deletions located within this intergenic space which remove either the transcription attenuation sequence or the RNase III mRNA processing sequence or both sequences have been isolated on recombinant DNA plasmids carrying this operon. Deletions of sequences surrounding the RNase III processing site result in a uniform 80-90% reduction in the translational efficiency of beta subunit mRNA. This reduction in translation efficiency appears not to be related to processing per se; transcription of the rpoB and rpoC genes and the translation efficiency of the respective mRNA sequences were indistinguishable in an RNase III processing defective mutant (rnc) and its isogenic parent (rnc+). Deletions of the attenuator sequence result in a substantial increase in the downstream transcription of the beta subunit gene. The translational efficiency of RNase III processed beta subunit mRNA was found to be related in an inverse manner to the level of beta subunit synthesis. These result suggest that sequences on the mRNA in the vicinity of the RNase III processing site (i) are essential for efficient translation of beta subunit mRNA and (ii) are utilized for reducing the translational efficiency of the beta subunit mRNA when the beta subunit protein is produced in excess of that required for RNA polymerase assembly.
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PMID:Site specific deletions of regulatory sequences in a ribosomal protein-RNA polymerase operon in Escherichia coli. Effects on beta and beta' gene expression. 632 99

Transiently stable products derived from the endonuclease cleavage of transcripts from the secEnusG and rplKAJLrpoBC operons have been identified. Cleavage sites for RNase III occur in the leader of the secEnusG transcript and in the L12-beta intercistronic space of the rplKAJLrpoBC transcript. A single RNase E cleavage site was located in the L1-L10 intergenic space. Inactivation of RNase III and RNase E results respectively in a one- to twofold and a greater than 10-fold stabilization of five mRNA sequences from within the secE, nusG, L11-L1, L10 and beta encoding cistrons. The relative amounts of each of these five mRNA sequences were found to be nearly constant when measured either in the presence or absence of cleavage by RNase III or RNase E. This clearly implies that any increases in the stability of these mRNA sequences resulting from the inactivation of processing by RNase III or RNAase E are counterbalanced by changes in the mRNA synthesis rates. The mechanism that links mRNA synthesis to mRNA decay is not known.
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PMID:Coupling between mRNA synthesis and mRNA stability in Escherichia coli. 751 86

The ribonuclease III Dicer (Dcr1) has been shown to be required for chromosome segregation and gene silencing in Schizosaccharomyces pombe. These effects are thought to be transcriptional, mediated by formation and maintenance of heterochromatin, and guided by small RNAs derived from Dcr1 along a process known as RNA interference. In order to get further insights into the gene regulatory role of Dcr1, we performed comparative analyses of dcr1 knockout and wild-type fission yeast strains. Analysis of part of the soluble proteomes identified eight cellular proteins whose expression is under Dcr1 control, three of which are integral constituents of the glycolysis pathway. Further correlations with their respective mRNA transcript levels are compatible with the existence of a post-transcriptional gene regulatory mechanism involving Dcr1 or a Dcr1 complex. Experiments designed to identify components of Dcr1 complexes unveiled two novel Dcr1 interactors, namely the zinc finger protein Byr3 and the ribosomal protein L12. Consistently enriched in Dcr1 immune complexes, Byr3 and L12 may link Dcr1 to the transcriptional and translational machineries, respectively, and contribute to post-transcriptional gene regulation in fission yeast.
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PMID:Involvement of Dcr1 in post-transcriptional regulation of gene expression in Schizosaccharomyces pombe. 1798 3