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:3.1.26.3 (RNase III)
1,015 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The primary transcript of pnp, the gene encoding polynucleotide phosphorylase in Escherichia coli, is processed in the 5' end region by ribonuclease III (RNase III). The unprocessed transcript shows enhanced stability compared with the processed transcript. We report here that, unlike the processed transcript, the unprocessed pnp transcript did not accept endonucleolytic attack at, at least, five cleavage sites. Sequencing analysis of the four cleavage products shows no sequence specific to all these sites, but AU rich stretches were observed at three sites.
...
PMID:Processing in the 5' region of the pnp transcript facilitates the site-specific endonucleolytic cleavages of mRNA. 137 67

The replication frequency of plasmid R1 is regulated by an antisense RNA, CopA, which inhibits the synthesis of the rate-limiting initiator protein RepA. The inhibition requires an interaction between the antisense RNA and its target, CopT, in the leader of the RepA mRNA. This binding reaction has previously been studied in vitro, and the formation of a complete RNA duplex between the two RNAs has been demonstrated in vitro and in vivo. Here we investigate whether complete duplex formation is required for CopA-mediated inhibition in vivo. A mutated copA gene was constructed, encoding a truncated CopA which is impaired in its ability to form a complete CopA/CopT duplex, but which forms a primary binding intermediate (the 'kissing complex'). The mutated CopA species (S-CopA) mediated incompatibility against wild-type R1 plasmids and inhibited RepA-LacZ fusion protein synthesis. Northern blot, primer extension and S1 analyses indicated that S-CopA did not form a complete duplex with CopT in vivo since bands corresponding to RNase III cleavage products were missing. An in vitro analysis supported the same conclusion. These data suggest that formation of the 'kissing complex' suffices to inhibit RepA synthesis, and that complete CopA/CopT duplex formation is not required. The implications of these findings are discussed.
...
PMID:Replication control in plasmid R1: duplex formation between the antisense RNA, CopA, and its target, CopT, is not required for inhibition of RepA synthesis. 137 49

1. A precursor to small stable RNA, 10Sa RNA, accumulates in large amounts in a temperature sensitive RNase E mutant at non-permissive temperatures, and somewhat in an rnc (RNase III-) mutant, but not in an RNase P- mutant (rnp) or wild type E. coli cells. 2. Since p10Sa RNA was not processed by purified RNase E and III in customary assay conditions, we purified p10Sa RNA processing activity about 700-fold from wild type E. coli cells. 3. Processing of p10Sa RNA by this enzyme shows an absolute requirement for a divalent cation with a strong preference for Mn2+ over Mg2+. Other divalent cations could not replace Mn2+. 4. Monovalent cations (NH+4, Na+, K+) at a concentration of 20 mM stimulated the processing of p10Sa RNA and a temperature of 37 degrees C and pH range of 6.8-8.2 were found to be optimal. 5. The enzyme retained half of its p10Sa RNA processing activity after 30 min incubation at 50 degrees C. 6. Further characterization of this activity indicated that it is RNase III. 7. To further confirm that the p10Sa RNA processing activity is RNase III, we overexpressed the RNase III gene in an E. coli cells that lacks RNase III activity (rnc mutant) and RNase III was purified using one affinity column, agarose.poly(I).poly(C). 8. This RNase III preparation processed p10Sa RNA in a similar way as observed using the p10Sa RNA processing activity purified from wild type E. coli cells, confirming that the first step of p10Sa RNA processing is carried out by RNase III.
...
PMID:Characterization of the RNA processing enzyme RNase III from wild type and overexpressing Escherichia coli cells in processing natural RNA substrates. 137 63

Characterization of the maturation of precursor 10Sa RNA revealed that RNase III processed p10Sa RNA to two intermediate molecules. We showed that the intermediates are not conformers and both are larger than the mature 10Sa RNA. Cell extracts further process the RNase III products to an RNA molecule which has a different conformation than 10Sa RNA but is approximately the same size as 10Sa RNA. An inhibitor of p10Sa RNA processing by RNase III was identified. It is a protein, with a molecular mass of approximately 17 kDa.
...
PMID:10Sa RNA: processing by and inhibition of RNase III. 137 35

The hok/sok, srnB and pnd systems of plasmids R1, F and R438 mediate plasmid maintenance by killing plasmid-free segregants. The systems encode exceptionally stable full-length mRNAs that code for potent cell toxins that kill the cells from within. The systems also produce truncated mRNAs whose appearance is correlated with killing activity. The truncated mRNAs are shortened by 35 to 70 nucleotides in the 3' ends, but have the same 5' ends as the full-length transcripts. Translation of the stable killer mRNAs is regulated by unstable antisense RNAs that are complementary to the leader regions of the full-length and truncated mRNAs. We show here, that both the presence of the antisense RNA and of the host enzyme RNase III is required for rapid cleavage of the truncated mRNAs, and we map the cleavage point in the Hok mRNA in vitro and in vivo to be located between nucleotides +245 and +246. The RNase III cleavage products of the Hok mRNA were found to be very unstable in vivo. Thus, RNase III cleavage seems to be the initial event leading to decay of the killer mRNAs. In an rnc- strain, the truncated mRNA species were found in steady-state cells. This observation indicates that the truncated mRNAs are formed constitutively and independently of the presence of the antisense RNAs. Thus, the antisense RNAs prevent the accumulation of the truncated mRNAs solely by mediating their rapid hydrolysis by RNase III. Furthermore, the generation of the truncated killer mRNAs in the rnc- host indicate that RNase III is dispensable for induction of the killer gene systems. Based on these and on observations obtained previously, we present a molecular model that explains the activation of the killer mRNAs in plasmid-free segregants and after addition of rifampicin.
...
PMID:Mechanism of killer gene activation. Antisense RNA-dependent RNase III cleavage ensures rapid turn-over of the stable hok, srnB and pndA effector messenger RNAs. 138 May 62

We have identified a double-stranded (ds)RNA-binding domain in each of two proteins: the product of the Drosophila gene staufen, which is required for the localization of maternal mRNAs, and a protein of unknown function, Xlrbpa, from Xenopus. The amino acid sequences of the binding domains are similar to each other and to additional domains in each protein. Database searches identified similar domains in several other proteins known or thought to bind dsRNA, including human dsRNA-activated inhibitor (DAI), human trans-activating region (TAR)-binding protein, and Escherichia coli RNase III. By analyzing in detail one domain in staufen and one in Xlrbpa, we delimited the minimal region that binds dsRNA. On the basis of the binding studies and computer analysis, we have derived a consensus sequence that defines a 65- to 68-amino acid dsRNA-binding domain.
...
PMID:A conserved double-stranded RNA-binding domain. 143 2

To assess the involvement of the RNA cleavage site-proximal 2' hydroxyl group in the RNase III catalytic mechanism, a specific processing substrate was chemically synthesized to contain a 2'-deoxyribose residue at the scissile phosphodiester bond. The RNA substrate, corresponding to the phage T7 R1.1 primary processing signal, can be accurately cleaved in vitro by RNase III. A fully deoxyribose-substituted R1.1 processing signal is not cleaved by RNase III, nor does it in excess inhibit cleavage of unmodified substrate. These results show that the 2' hydroxyl group proximal to the scissile bond is not an essential participant in the RNase III processing reaction; however, other 2' hydroxyl groups are important for substrate reactivity, and may be involved in establishing proper double helical conformation, and/or specific substrate contacts with RNase III.
...
PMID:Accurate enzymatic cleavage in vitro of a 2'-deoxyribose-substituted ribonuclease III processing signal. 153 83

It has been previously shown that the pnp messenger RNAs are cleaved by RNase III at the 5' end and that these cleavages induce a rapid decay of these messengers. A translational fusion between pnp and lacZ was introduced into the chromosome of a delta lac strain to study the expression of pnp. In the presence of increased cellular concentrations of polynucleotide phosphorylase, the level of the hybrid beta-galactosidase is repressed, whereas the synthesis rate of the corresponding message is not significantly affected. In the absence of pnp, the level of the hybrid protein increases strongly. Thus, polynucleotide phosphorylase is post-transcriptionally autocontrolled. However, autocontrol is totally abolished in strains where the RNase III site on the pnp message has been deleted or in strains devoid of RNase III. These results suggest that polynucleotide phosphorylase requires RNase III cleavages to autoregulate the translation of its message. Other mutations in the ribosome binding site region support the hypothesis that this 3' to 5' processive enzyme could recognize a specific repressor binding site at the 5' end of pnp mRNA. Implications of these results on the mechanism of regulation and on messenger degradation are discussed.
...
PMID:E.coli polynucleotide phosphorylase expression is autoregulated through an RNase III-dependent mechanism. 162 24

RNA stability is an important component of gene expression, and antisense RNAs have been proposed to alter target RNA stability. We show here that the IS10 transposase mRNA, RNA-IN, is rendered unstable during control by the IS10 antisense RNA, RNA-OUT. Destabilization requires RNA-OUT/RNA-IN pairing and ribonuclease III cleavage. Independent of such cleavage, RNA-OUT is rendered unstable through disruption of its secondary structure. Pairing has no other obvious effects on RNA-IN transcription or stability. Nevertheless, RNA-IN destabilization is not required for antisense control in vivo. In the accompanying paper [Ma,C. and Simons, R.W. (1990) EMBO J., 9, 1267-1274 we show that pairing blocks ribosome binding to RNA-IN. Were it not for control at this level, destabilization would play a more prominent role.
...
PMID:The IS10 transposase mRNA is destabilized during antisense RNA control. 169 Oct 96

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.
...
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


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

---