Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to identify multicomponent complexes involved in kinetoplastid mitochondrial mRNA editing. Mitochondrial extracts from Trypanosoma brucei were fractionated on 10-30% glycerol gradients and assayed for RNAs and activities potentially involved in editing, including pre-edited mRNA, guide RNA (gRNA), endonuclease, terminal uridylyltransferase (TUTase), RNA ligase and gRNA-mRNA chimera-forming activities. These experiments suggest that two distinct editing complexes exist. Complex I (19S) consists of gRNA, TUTase, RNA ligase and chimera-forming activity. Complex II (35-40S) is composed of gRNA, preedited mRNA, RNA ligase and chimera-forming activity. These studies provide the first evidence that editing occurs in a multicomponent complex. The possible roles of complex I, complex II and RNA ligase in editing are discussed.
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PMID:Native mRNA editing complexes from Trypanosoma brucei mitochondria. 133 May 37

By using a band mobility shift assay, deoxyinosine 3'-endonuclease, an Escherichia coli enzyme which recognizes deoxyinosine, AP site, urea residue, and base mismatches in DNA, was shown to bind tightly to deoxyinosine-containing oligonucleotide duplexes. Two distinct protein-DNA complexes were observed, the faster migrating complex (complex I, Kd = 4 x 10(-9) M) contained one molecule of deoxyinosine 3'-endonuclease, while the slower migrating complex (complex II, Kd = 4 x 10(-7) M) contained two molecules of the protein bound to every molecule of duplex DNA. The endonucleolytic activity of deoxyinosine 3'-endonuclease paralleled the formation of the complex I. Interestingly, deoxyinosine 3'-endonuclease exhibited similar affinities for both the substrate and the nicked duplex product and thus remained bound to the DNA after the cleavage reaction. The formation of a stable complex required the presence of a duplex structure 5' to the deoxyinosine residue. DNase I footprinting revealed that deoxyinosine 3'-endonuclease protected 4-5 nucleotides 5' to the deoxyinosine, and when complex II was formed, at least 13 nucleotides 3' to deoxyinosine were protected. Based on these results, a model is proposed for the interaction of deoxyinosine 3'-endonuclease with DNA containing deoxyinosine.
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PMID:Interaction of deoxyinosine 3'-endonuclease from Escherichia coli with DNA containing deoxyinosine. 749 77

Phage lambda, like a number of other large DNA bacteriophages and the herpesviruses, produces concatemeric DNA during DNA replication. The concatemeric DNA is processed to produce unit-length, virion DNA by cutting at specific sites along the concatemer. DNA cutting is co-ordinated with DNA packaging, the process of translocation of the cut DNA into the preformed capsid precursor, the prohead. A key player in the lambda DNA packaging process is the phage-encoded enzyme terminase, which is involved in (i) recognition of the concatemeric lambda DNA; (ii) initiation of packaging, which includes the introduction of staggered nicks at cosN to generate the cohesive ends of virion DNA and the binding of the prohead; (iii) DNA packaging, possibly including the ATP-driven DNA translocation; and (iv) following translocation, the cutting of the terminal cosN to complete DNA packaging. To one side of cosN is the site cosB, which plays a role in the initiation of packaging; along with ATP, cosB stimulates the efficiency and adds fidelity to the endonuclease activity of terminase in cutting cosN. cosB is essential for the formation of a post-cleavage complex with terminase, complex I, that binds the prohead, forming a ternary assembly, complex II. Terminase interacts with cosN through its large subunit, gpA, and the small terminase subunit, gpNu1, interacts with cosB. Packaging follows complex II formation. cosN is flanked on the other side by the site cosQ, which is needed for termination, but not initiation, of DNA packaging. cosQ is required for cutting of the second cosN, i.e. the cosN at which termination occurs. DNA packaging in lambda has aspects that differ from other lambda DNA transactions. Unlike the site-specific recombination system of lambda, for DNA packaging the initial site-specific protein assemblage gives way to a mobile, translocating complex, and unlike the DNA replication system of lambda, the same protein machinery is used for both initiation and translocation during lambda DNA packaging.
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PMID:Virus DNA packaging: the strategy used by phage lambda. 857 44

The genes encoding succinate dehydrogenase (sdhCDAB), the specific components of the 2-oxoglutarate dehydrogenase complex (ODH, E1o and E2o; sucAB) and succinyl-CoA synthetase (sucCD) form a cluster containing two promoters at 16.3 min in the chromosome of Escherichia coli: Psdh sdhCDAB-Psuc sucAB-sucCD. The gene encoding the lipoamide dehydrogenase component of both the 2-oxoglutarate and pyruvate dehydrogenase complexes (E3; lpdA) is the distal gene of another cluster containing two promoters located at 2.7 min: Ppdh pdhR-aceEF-Plpd lpdA. The responses of the suc and lpd promoters to different environmental conditions and to regulator defects were investigated with appropriate lacZ fusions, in order to understand how expression of the sucAB genes is co-regulated with other genes in the sdhCDAB-sucABCD cluster and with lpdA expression. Expression from the suc promoter was repressed by IHF and partially activated by sigma 38 but it was not regulated by ArcA, FNR, CRP, FruR or Fis, and not repressed by glucose or anaerobiosis, indicating that the well-established catabolite and anaerobic repression of ODH synthesis is imposed elsewhere. In contrast, the lpd promoter was repressed by both glucose (via a CRP-independent mechanism) and anaerobiosis (mediated by ArcA), and activated by Fis, but it was not regulated by FNR, FruR, IHF or sigma 38. These observations support the view that transcription of the sucABCD genes is primarily initiated and regulated at the upstream sdh promoter, and that the lpd promoter is independently co-regulated with Psdh (primarily by ArcA-mediated repression) rather than with Psuc. Direct evidence for co-transcription of the entire sdhCDAB-sucABCD region from Psdh was obtained by detecting a 10 kb transcript in rnc and rne mutants, but not in the parental strains. Three RNaseIII-specific processing sites, which contribute to the extreme instability of the readthrough transcript, were identified in the sdhCDAB-sucABCD intergenic region. Other sites of endonuclease processing were located by interpreting the patterns of transcript subfragments observed in Northern blotting.
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PMID:Transcription and transcript processing in the sdhCDAB-sucABCD operon of Escherichia coli. 972 32

Oxidative stress and mitochondrial dysfunction are considered to be activators of apoptosis and serve a pivotal role in the pathogenesis of myocardial ischemia-reperfusion (MI/R) injury. Apurinic/apyrimidinic endonuclease/redox factor 1 (APE1) is a multifunctional protein that processes the cellular response to DNA damage and oxidative stress. Little is known about the role of APE1 in the pathogenesis of MI/R injury. The aim of the present study was to investigate the effects of APE1 on hypoxia-reoxygenation (H/R)-induced H9c2 cardiomyocyte injury and the underlying mechanism responsible. It was demonstrated that H/R decreased cell viability and increased lactic dehydrogenase (LDH) release, as well as reducing APE1 expression in H9c2 cells. However, APE1 overexpression induced by transfection with APE1-expressing lentivirus significantly increased H9c2 cell viability, decreased LDH release, decreased apoptosis and reduced caspase-3 activity in H/R-treated H9c2 cells. APE1 overexpression ameliorated the H/R-induced increases in reactive oxygen species and NAPDH oxidase expression, as well as the decreases in superoxide dismutase activity and glutathione expression. Furthermore, APE1 overexpression increased mitochondrial membrane potential and ATP production, stabilized electron transport chain activity (as illustrated by increased NADH-ubiquinone oxidoreductase, succinate dehydrogenase, coenzyme Q-cytochrome c oxidoreductase and cytochrome c oxidase activities) and decreased the ratio of B-cell lymphoma 2-associated X protein/B-cell lymphoma 2 in H/R, improving mitochondrial dysfunction. In conclusion, the results of the present study suggest that APE1 alleviates H/R-induced injury in H9c2 cells by attenuating oxidative stress and ameliorating mitochondrial dysfunction. APE1 may therefore be used as an effective treatment for MI/R injury.
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PMID:Apurinic/apyrimidinic endonuclease/redox factor 1 (APE1) alleviates myocardial hypoxia-reoxygenation injury by inhibiting oxidative stress and ameliorating mitochondrial dysfunction. 3086 2