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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A brief exposure to elevated temperatures elicits, in all organisms, a transient state of increased heat resistance known as thermotolerance. The mechanism for this thermotolerant state is unknown primarily because it is not clear how mild hyperthermia leads to cell death. The realization that cell death can occur through an active process of self destruction, known as apoptosis, led us to consider whether thermotolerance provides protection against this mode of cell death. Apoptosis is a common and essential form of cell death that occurs under both physiological and pathological conditions. This mode of cell death requires the active participation of the dying cell and in this way differs mechanistically from the alternative mode of cell death, necrosis. Here we show that mild hyperthermia induces apoptosis in a human leukemic T cell line. This is evidenced by chromatin condensation, nuclear fragmentation and the cleavage of DNA into oligonucleosome size units. DNA fragmentation is a biochemical hallmark of apoptosis and requires the activation of an endogenous endonuclease. The extent of DNA fragmentation was proportional to the severity of heat stress for cells heated at 43 degrees C from 30 to 90 minutes. A brief conditioning heat treatment induced a resistance to apoptosis. This was evident as a resistance to DNA fragmentation and a reduction in the number of apoptotic cells after a heat challenge. Resistance to DNA fragmentation developed during a recovery period at 37 degrees C and was correlated with enhanced heat shock protein (hsp) synthesis. This heat-induced resistance to apoptosis suggests that thermotolerant cells have gained the capacity to prevent the onset of this pathway of self-destruction. An examination of this process in heated cells should provide new insights into the molecular basis of cellular thermotolerance.
...
PMID:Induced thermotolerance to apoptosis in a human T lymphocyte cell line. 129 3

Programmed cell death or apoptosis occurs under physiological conditions as a result of physiological effectors. It is a relatively slower process and requires active participation of the cell in the suicidal mechanism. Apoptosis is controlled by precise intrinsic genetic programme and may be induced by almost all those stimuli causing necrosis. The role played by the intensity in determining the death process and the underlying mechanism is imperfectly understood. Morphologically apoptotic cells appear as small condensed body. The chromatin is dense and fragmented, packed into compact membrane-bound bodies together with randomly distributed cell organelles. The plasma membrane loses its characteristic architecture and shows extensive blebbing. It buds off projections so that the whole cell may split into several membrane-bound apoptotic bodies. Significant chemical changes take place in the plasma membrane. This helps in recognition of the apoptotic bodies by phagocytes. At this moment it is unclear if all cells can undergo apoptosis or it is a characteristic of only some tissues which are predisposed to apoptotic death being directly under the control of hormones or growth factors. Experimental studies aimed at comparison of induction of apoptosis in cells of different origin are warranted to elucidate this point. Biochemically a pre-commitment step for induction of death programmation through macromolecular synthesis is essential for most systems. The double-stranded linker DNA between nucleosomes is cleaved at regular inter-nucleosomal sites through the action of a Ca2+, Mg(2+)-sensitive neutral endonuclease. Zinc is a potent inhibitor of the enzyme. Calcium probably plays a key controlling role in activation of the enzyme since prevention of Ca2+ increase prevents endonuclease activation. It is becoming evident that signal transduction through appropriate receptors control the Ca2+ flux in the cells. Most apoptotic cells require synthesis of RNA and proteins. Delay or abrogation of apoptosis by inhibition of macromolecular synthesis is well known. The dying cells show high mRNA levels for several enzymes. Several degradative enzymes become active. Regulatory proteins maintain control over the apoptotic cascade. At the molecular level, search has been initiated for the mammalian equivalents of the cell death (ced) gene. Activation of several specific genes is indicated. Specific expression of cell death-associated gene products (e.g. TRPM-2/SGP-2) has been reported in several unrelated apoptotic cell systems. Sequential induction of c-fos, c-myc and 70 kDa heat shock protein is reported. Studies demonstrate that certain genes must remain in a transcriptionally active demethylated state during programmed cell death. Recent evidences clearly indicate that apoptosis may be positively or negatively modulated by certain genes.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Programmed cell death: concept, mechanism and control. 142 Jul 28

Endo.SceI of Saccharomyces cerevisiae is a heterodimeric site-specific endonuclease, which is distinguishable from prokaryotic restriction endonucleases in the mode of recognition of its cleavage site. We have used monoclonal antibodies specific to the larger subunit (75 kDa) of Endo.SceI to isolate the gene for the subunit (ENS1) from S. cerevisiae. Unexpectedly, ENS1 was found to encode a 70-kDa heat shock protein-related polypeptide and to be identical to recently cloned SSC1. Subcellular fractionation experiments on yeast cells revealed that the primary target site of the larger subunit is mitochondria, where almost all the Endo.SceI activity is localized. Molecular genetic analysis of ENS1 demonstrated its indispensability for growth and the requirement of a high level of its expression at the sporulation and germination stages. The data suggest that ENS1 plays an important role, especially at these differentiation stages.
...
PMID:A subunit of yeast site-specific endonuclease SceI is a mitochondrial version of the 70-kDa heat shock protein. 220 71

Two-dimensional gel analyses were made of proteins synthesized in Escherichia coli during various O2- -generating conditions. Nine proteins were constitutively synthesized over wild-type levels in superoxide dismutase (sodA sodB) double mutants. Addition of redox cycling agents such as paraquat and plumbagin at various concentrations induced up to 13 proteins in wild-type cells. Among these 13 were 5 of the 9 constitutively synthesized in the sodA sodB double mutants. Addition of these agents to the superoxide dismutase mutants in low micromolar concentrations induced an additional set of 14 proteins. The proteins induced included only five proteins that have been previously associated with stress responses, consisting of endonuclease IV (Nfo), three oxyR-regulated proteins, and one heat shock protein. O2- -mediated induction of the superoxide inducible (Soi) proteins in the wild type was independent of the oxyR+ gene for all but the three oxyR-regulated proteins. Analyses of proteins from three soi::lacZ gene fusions previously isolated (T. Kogoma, S. B. Farr, K. M. Joyce, and D. O. Natvig, Proc. Natl. Acad. Sci. USA 85:4799-4803, 1988) indicated the specific loss of one of these induced proteins in each fusion strain and the constitutive expression of some Soi proteins.
...
PMID:Escherichia coli proteins inducible by oxidative stress mediated by the superoxide radical. 253 20

RFLP in the hsp70 gene encoding a major heat shock protein was analyzed in rat strains with high and normal arterial blood pressure. Dimorphism in the sets of DNA fragments was revealed after hybridization of the hsp gene leader sequence with rat DNA digested with BamHI restriction endonuclease. Type I RFLP was represented by the fragments of 12,200, 6500, 41,000 and 1600 bp in size. Type II RFLP corresponded to the set that included the fragments of 12,200, 6500, 2900, 1600, and 1200 bp in size. Interstrain polymorphism was demonstrated for the fragments of 4100, 2900 and 1200 bp. Furthermore, analysis of different rat strains showed that the 2900- and 1200-bp fragments were linked and formed by cleavage of the 4100-bp fragment with restriction endonuclease. This polymorphism was probably caused by the point A-->T mutation occurring in the BamHI recognition site located in the leader sequence of the hsp70 gene at a distance of +35 bp from the coding sequence. Examination of interstrain RFLP in the hsp70 gene indicated that the presence of 2900-bp fragment was not associated with hypertensive status in all experimental models of inherited arterial hypertension. This confirms the assumption on genetic heterogeneity of this common disease.
...
PMID:[Polymorphism of the gene of heat shock protein hsp70 in lines of rats with normal and hypertensive status]. 958 65

The multisite-specific endonuclease Endo.SceI of yeast mitochondria is unique among endonucleases because its 50-kDa subunit forms a stable dimer with the mitochondrial 70-kDa heat shock protein (mtHSP70), which otherwise fulfills a chaperone function by binding transiently to unfolded proteins. Here we show that the mtHSP70 subunit confers broader sequence specificity, greater stability, and higher activity on the 50-kDa subunit. The 50-kDa subunit alone displayed weaker activity and highly sequence-specific endonuclease activity. The 50-kDa protein exists as a heterodimer with mtHSP70 in vivo, allowing Endo.SceI to cleave specifically at multiple sites on mitochondrial DNA. Endo.SceI may have evolved from a highly specific endonuclease that gained broader sequence specificity after becoming a stable partner of mtHSP70.
...
PMID:Stable association of 70-kDa heat shock protein induces latent multisite specificity of a unisite-specific endonuclease in yeast mitochondria. 1046 5

Identification of clinical isolates of Nocardia to the species level is important for defining the spectrum of disease produced by each species and for predicting antimicrobial susceptibility. We evaluated the usefulness of PCR amplification of a portion of the Nocardia 16S rRNA gene and subsequent restriction endonuclease analysis (REA) for species identification. Unique restriction fragment length polymorphism (RFLP) patterns were found for Nocardia sp. type strains (except for the N. asteroides type strain) and representative isolates of the drug pattern types of Nocardia asteroides (except for N. asteroides drug pattern type IV, which gave inconsistent amplification). A variant RFLP pattern for Nocardia nova was also observed. Twenty-eight clinical isolates were evaluated both by traditional biochemical identification and by amplification and REA of portions of the 16S rRNA gene and the 65-kDa heat shock protein (HSP) gene. There was complete agreement among the three methods on identification of 24 of these isolates. One isolate gave a 16S rRNA RFLP pattern consistent with the biochemical identification but was not identifiable by its HSP gene RFLP patterns. Three isolates gave 16S rRNA RFLP patterns which were inconsistent with the identification obtained by both biochemical tests and HSP gene RFLP; sequence analysis suggested that two of these isolates may belong to undefined species. The PCR and REA technique described appears useful both for the identification of clinical isolates of Nocardia and for the detection of new or unusual species.
...
PMID:Identification of nocardia species by restriction endonuclease analysis of an amplified portion of the 16S rRNA gene. 1061 80

A subpopulation of the 70 kDa heat shock protein (HSP70) found within the mitochondria of Saccharomyces cerevisiae functions as a stable binding partner of the endonuclease SceI. We have previously found that the SceI endonuclease monomer recognizes and cleaves a unique, 26 bp sequence in vitro. Dimerization with HSP70 changes the specificity of SceI, allowing it to cleave at multiple sequences. This study shows that SuvI, an ortholog of SceI isolated from a different yeast strain, contains two amino acid substitutions, yet it shows the same uni-site specificity in its monomeric form. Binding of HSP70 to the SuvI monomer confers multi-site specificity that is different from that exhibited by the HSP70/SceI heterodimer. Mutation of single residues of SceI to the corresponding residue in SuvI provides enzymes with specificities intermediate between SceI and SuvI when complexed with HSP70. These results suggest that HSP70 interaction with certain endonucleases allows the expression of otherwise silent mutations in them, causing a change in enzyme cleavage specificity.
...
PMID:Association of HSP70 with endonucleases allows the expression of otherwise silent mutations. 1209 41

A new RTE-like, non-long terminal repeat retrotransposon, termed SjR2, from the human blood fluke, Schistosoma japonicum, is described. SjR2 is approximately 3.9 kb in length and is constituted of a single open reading frame encoding a polyprotein with apurinic/apyrimidinic endonuclease and reverse transcriptase domains. The open reading frame is bounded by 5'- and 3'-terminal untranslated regions and, at its 3'-terminus, SjR2 bears a short (TGAC)(3) repeat. Phylogenetic analyses based on conserved domains of reverse transcriptase or endonuclease revealed that SjR2 belonged to the RTE clade of non-long terminal repeat retrotransposons. Further, SjR2 was homologous, but probably not orthologous, to SR2 from the African blood fluke, Schistosoma mansoni; this RTE-like family of non-long terminal repeat retrotransposons appears to have arisen before the divergence of the extant schistosome species. Hybridisation analyses indicated that approximately 10,000 copies of SjR2 were dispersed throughout the S. japonicum chromosomes, accounting for up to 14% of the nuclear genome. Messenger RNAs encoding the reverse transcriptase and endonuclease domains of SjR2 were detected in several developmental stages of the schistosome, indicating that the retrotransposon was actively replicating within the genome of the parasite. Exploration of the coding and non-coding regions of SjR2 revealed two notable characteristics. First, the recombinant reverse transcriptase domain of SjR2 expressed in insect cells primed reverse transcription of SjR2 mRNA in vitro. By contrast, recombinant SjR2-endonuclease did not appear to cleave schistosome or plasmid DNA. Second, the 5'-untranslated region of SjR2 was >80% identical to the 3'-untranslated region of a schistosome heat shock protein-70 gene (hsp-70) in the antisense orientation, indicating that SjR2-like elements were probably inserted into the non-coding regions of ancestral S. japonicum HSP-70, probably after the species diverged from S. mansoni.
...
PMID:Reverse transcriptase activity and untranslated region sharing of a new RTE-like, non-long terminal repeat retrotransposon from the human blood fluke, Schistosoma japonicum. 1211 99

Molecular methodologies have become useful techniques for the identification of pathogenic Nocardia species and for the recognition of novel species that are capable of causing human disease. Two isolates recovered from immunocompromised patients were characterized as Nocardia nova by biochemical and susceptibility testing results. The restriction fragment length polymorphism (RFLP) patterns obtained by restriction endonuclease analysis (REA) of an amplified portion of the heat shock protein gene were identical to those obtained with the type strain of N. nova. REA of an amplified portion of the 16S rRNA gene showed RFLP patterns that were unlike those obtained for the type strain of N. nova but that were similar to those obtained for the type strains of N. africana and N. veterana. Subsequent sequencing of a portion of the 16S rRNA gene produced identical results for the two patient isolates. Sequence analysis of 1,352-bp portions of the 16S rRNA gene indicated that these isolates were 99.8% similar to the recently described species N. veterana but were only 99.3, 98.1, and 98.1% similar to the type strains of N. africana, N. nova, and N. vaccinii, respectively. DNA-DNA hybridization studies confirmed that the two patient isolates belonged to the same species but were not closely related to N. africana, N. nova, N. vaccinii, or N. veterana. The patient isolates have been designated N. kruczakiae sp. nov. Because N. africana, N. veterana, and the new species are not readily differentiated from N. nova by phenotypic methods alone, the designation "N. nova complex" can be used to designate isolates such as these that phenotypically resemble N. nova but that have not been definitively characterized by 16S rRNA gene sequencing or DNA-DNA hybridization.
...
PMID:Nocardia kruczakiae sp. nov., a pathogen in immunocompromised patients and a member of the "N. nova complex". 1552 7


1 2 Next >>

---