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

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

Cystic fibrosis is the most common autosomal recessive disorder in Caucasian populations, with an approximate frequency of 1/2500 live births and a carrier frequency of 1/25. Due to the high rate of predicted carriers (> 63,000) in the Nebraska population (1990 U.S. Census = 1,578,358), we analyzed sperm DNA obtained from semen donors at the University of Nebraska Genetic Semen Bank for eight of the more common mutations to determine the frequency and diversity in our population. The subjects included 167 semen donors (31 normal healthy donors, 56 infertility patients, 21 prevasectomy patients, and 59 prechemotherapy or preradiation cancer patients). The mutations analyzed included delta F508, R117H, G542X, S549R/N, G551D, R553X, R560T, and W1282X. Analyses were performed using PCR amplified products that were analyzed using polyacrylamide gel electrophoresis, slot blot, and restriction endonuclease digestion. These results were correlated with results from the clinical semen analyses and selected clinical parameters. Results for the total donor population studied showed that the delta F508 mutation was present in 8/167 (4.8%) donors, the R117H mutation was present in 4/167 (2.4%) donors and the G542X mutation was present in 1/167 (0.6%) donors. The observed number of carriers from this population, 13/167 (7.8%), was significantly greater (P = 0.02) than that expected assuming a carrier frequency of 1/25. The excess of carriers was restricted to the subgroup of infertility patients. This suggests that CF carriers may be at higher risk for infertility than the general population.
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PMID:Mutation analysis for cystic fibrosis to determine carrier status in 167 sperm donors from the Nebraska Genetic Semen Bank. 786 6

We have shown elsewhere that acidification is an early event in apoptosis, preceding DNA cleavage. Cells expressing the most common mutation (delF508) of the cystic fibrosis transmembrane regulator (CFTR) exhibit a higher resting intracellular pH and are unable to secrete chloride and bicarbonate in response to cAMP. We hypothesized that defective acidification in cells expressing delF508 CFTR would interfere with the acidification that accompanies apoptosis, which in turn, would prevent endonuclease activation and cleavage of DNA. We therefore determined whether the function of the CFTR would affect the process of apoptosis in mouse mammary epithelial C127 cells stably transfected with the wild-type CFTR (C127/wt) or the delF508 mutation of the CFTR (C127/508). C127 cells possessed an acid endonuclease capable of DNA degradation at low pH. Sixteen hours after treatment with cycloheximide, C127/wt cells underwent cytoplasmic acidification. In contrast, C127/508 cells failed to demonstrate acidification. Furthermore, the C127/508 cells did not show nuclear condensation or DNA fragmentation detected by in situ nick-end labeling after treatment with cycloheximide or etoposide, in contrast to the characteristic features of apoptosis demonstrated by the C127/wt cells. Measurement of cell viability indicated a preservation of cell viability in C127/508 cells but not in C127/wt cells. That this resistance to the induction of apoptosis depended upon the loss of CFTR activity is shown by the finding that inhibition of the CFTR with diphenylamine carboxylate in C127/wt cells conferred similar protection. These findings suggest a role for the CFTR in acidification during the initiation of apoptosis in epithelial cells and imply that a failure to undergo programmed cell death could contribute to the pathogenesis of cystic fibrosis.
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PMID:Mutant cystic fibrosis transmembrane conductance regulator inhibits acidification and apoptosis in C127 cells: possible relevance to cystic fibrosis. 862 79

The respiratory tracts of bronchiectasis patients may be persistently colonized with Pseudomonas aeruginosa, despite intensive chemotherapy. The organism may undergo phenotypic changes in these patients, providing misleading typing results by conventional methods. We prospectively studied eight bronchiectasis patients without cystic fibrosis over a period of 1 year. A high microbial load of P. aeruginosa was found in 70% of sputum samples collected. Of these, 55 sequential P. aeruginosa isolates were characterized by a genotyping method, pulsed-field gel electrophoresis, to overcome the problem of differentiating the P. aeruginosa strains during chemotherapy. Genome macrorestriction fingerprinting patterns were analyzed after digestion with XbaI restriction endonuclease. Of the eight patients, six harbored a single dominant strain of P. aeruginosa, with an intrapatient macrorestriction similarity pattern range of 96 to 100%. The other two patients were infected with mixed bacterial isolates including P. aeruginosa. However, diversity was observed in the P. aeruginosa isolates from all eight patients, with a relatedness of only 55 to 65%. The study further strengthens the fact that pulsed-field gel electrophoresis can be used efficiently and effectively to differentiate P. aeruginosa strains in bronchiectasis patients without cystic fibrosis.
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PMID:Genome macrorestriction analysis of sequential Pseudomonas aeruginosa isolates from bronchiectasis patients without cystic fibrosis. 890 17

A variety of mutation detection techniques, including restriction endonuclease digestion, allele specific oligonucleotides, and automated fluorescent sequencing, were used in the identification of 15 CFTR mutations representing 86.7% of CF chromosomes in 206 Northern Irish cystic fibrosis (CF) families. A systematic analysis of the 27 exons and intron/exon boundaries of the CFTR gene was performed using denaturing gradient gel electrophoresis (DGGE) in an attempt to characterise the 55 unknown CF mutations in 51 patients. Twenty different mutations were detected by DGGE on 30 chromosomes accounting for a further 7.3% of CF alleles. Fifteen of these mutations had not previously been found in Northern Ireland, and two are novel, M1I(G > T) and V562L. In total, 30 CFTR mutations account for 93.9% of the 412 Northern Irish CF chromosomes tested. The three major CF mutations in Northern Ireland are delta F508, G551D, and R117H with respective frequencies of 68.0%, 5.1%, and 4.1%. The efficacy of the DGGE technique was proven by the detection of 77 out of 77 control variants from all the CFTR exons. DGGE is a highly efficient and sensitive method for mutation screening especially in large genes where the mutation spectrum is known to be heterogeneous.
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PMID:Mutation characterization of CFTR gene in 206 Northern Irish CF families: thirty mutations, including two novel, account for approximately 94% of CF chromosomes. 895 39

Because of conflicting data about hospital-based transmission of Burkholderia (Pseudomonas) cepacia, an important respiratory pathogen in cystic fibrosis (CF), we compared strains found in sputum, lung, or blood of 29 CF patients in our center from 1988 to 1994, studying the relationship between strain and hospital exposure of incident and that of prevalent cases. Exposure was defined as a concurrent hospital stay between a prevalent and an incident case. B. cepacia strains were determined by polymerase chain reaction (PCR) ribotyping and endonuclease subtyping. The 16S to 23S spacer regions of the bacterial ribosomal RNA (rRNA) genes were amplified by PCR, and the product-size patterns used to type each B. cepacia isolate. Endonuclease digestion of the PCR products provided length polymorphisms for subtyping. There were 17 incident events during the period from 1988 to 1994, 16 of which involved a single ribotype. These 16 ribotypes could be divided into five subtypes by endonuclease mapping. Four patients grew B. cepacia from the blood, with the organism being the same strain as found in the lung in each case. Case controls were obtained to evaluate risk factors for B. cepacia acquisition. Concurrent hospitalization with a prevalent case significantly increased the risk of acquisition. There was no association between length of hospitalization, length of exposure, or FEV1 and the risk of B. cepacia acquisition.
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PMID:PCR ribotyping and endonuclease subtyping in the epidemiology of Burkholderia cepacia infection. 911 36

Isolates of Pseudomonas aeruginosa from chronic lung infections in cystic fibrosis (CF) patients have phenotypes distinct from those initially infecting CF patients, as well as from other clinical or environmental isolates. To gain a better understanding of the differences in these isolates, protein expression was followed using two-dimensional (2-D) gel electrophoresis and protein identification by peptide sequencing using micro-capillary column liquid chromatography-tandem mass spectrometry (microLC/MS/MS). The isolates selected for this analysis were from the sputum of a CF patient: strain 383 had a nonmucoid phenotype typical of isolates from the environment, and strain 2192, obtained from the same patient, had a mucoid phenotype typical of isolates from chronic CF lung infections. Strains 383 and 2192 were confirmed to be genetically identical by restriction endonuclease analysis, random amplified polymorphic DNA-PCR, and pulsed-field gel electrophoresis. Conditions of protein extraction were optimized for consistent high-resolution separation of several hundred proteins from these clinical isolates as detected by Coomassie staining of 2-D gels. Fourteen proteins were selected for analysis; this group included those whose expression was common between both strains as well as unique for each strain. The proteins were identified by microLC/MS/MS of the peptides produced by an in-gel tryptic digestion and compared to translated data from the Pseudomonas Genome Project; optimization of this technique has allowed for the comparison of proteins expressed by strains 383 and 2192.
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PMID:Comparison of proteins expressed by Pseudomonas aeruginosa strains representing initial and chronic isolates from a cystic fibrosis patient: an analysis by 2-D gel electrophoresis and capillary column liquid chromatography-tandem mass spectrometry. 1102 25

Data on five single-nucleotide polymorphisms (SNPs) per gene are estimated to allow association of disease risks or pharmacogenetic parameters with individual genes. Efficient technologies for rapidly detecting SNPs will therefore facilitate the mining of genomic information. Known methods for SNP analysis include restriction-fragment-length polymorphism polymerase chain reaction (PCR), allele-specific oligomer hybridization, oligomer-specific ligation assays, minisequencing, direct sequencing, fluorescence-detected 5'-exonuclease assays, and hybridization with PNA probes. Detection by mass spectrometry (MS) offers speed and high resolution. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) can detect primer extension products, mass-tagged oligonucleotides, DNA created by restriction endonuclease cleavage, and genomic DNA. We have previously reported MALDI-TOF-monitored nuclease selections of modified oligonucleotides with increased affinity for targets. Here we use nuclease selections for genotyping by treating DNA to be analyzed with oligonucleotide probes representing known genotypes and digesting probes that are not complementary to the DNA. With phosphodiesterase I, the target-bound, complementary probe is largely refractory to nuclease attack and its peak persists in mass spectra (Fig. 1A). In optimized assays, both alleles of a heterozygote were genotyped with six nonamer DNA probes (> or = 125 fmol each) and asymmetrically amplified DNA from exon 10 of the cystic fibrosis transmembrane regulatory gene (CFTR).
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PMID:Rapid genotyping by MALDI-monitored nuclease selection from probe libraries. 1106 45

DNase II alpha (EC 3.1.22.1) is an endonuclease, which is active at low pH, that cleaves double-stranded DNA to short 3'-phosphoryl oligonucleotides. Although its biochemistry is well understood, its structure-activity relationship has been largely unexamined. Recently, we demonstrated that active DNase II alpha consists of one contiguous polypeptide, heavily glycosylated, and containing at least one intrachain disulphide linkage [MacLea, Krieser and Eastman (2002) Biochem. Biophys. Res. Commun. 292, 415-421]. The present paper describes further work to examine the elements of DNase II alpha protein required for activity. Truncated forms and site-specific mutants were expressed in DNase II alpha-null mouse cells. Results indicate that the signal-peptide leader sequence is required for correct glycosylation and that N-glycosylation is important for formation of the active enzyme. Despite this, enzymic deglycosylation of wild-type protein with peptide N-glycosidase F reveals that glycosylation is not intrinsically required for DNase activity. DNase II alpha contains six evolutionarily conserved cysteine residues, and mutations in any one of these cysteines completely ablated enzymic activity, consistent with the importance of disulphide bridging in maintaining correct protein structure. We also demonstrate that a mutant form of DNase II alpha that lacks the purported active-site His(295) can still bind DNA, indicating that this histidine residue is not simply involved in DNA binding, but may have a direct role in catalysis. These results provide a more complete model of the DNase II alpha protein structure, which is important for three-dimensional structural analysis and for production of DNase II alpha as a potential protein therapeutic for cystic fibrosis or other disorders.
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PMID:Structural requirements of human DNase II alpha for formation of the active enzyme: the role of the signal peptide, N-glycosylation, and disulphide bridging. 1255 98

Cross-infection with Pseudomonas aeruginosa is an emerging issue in the care of patients with cystic fibrosis (CF). This study sought to determine the extent of, and patient factors associated with, cross-infection in a tertiary referral adult CF centre. P. aeruginosa isolates were genotyped into two groups between November 2001 and February 2003, using pulsed-field gel electrophoresis after DNA digestion by the SpeI endonuclease, and identified as clustered if there was >80% homology in the macrorestriction profiles. Patient factors and measures of disease severity were identified a priori. In total, 157 out of 227 patients had a P. aeruginosa isolate genotyped. Of these, 94 patients (60%) were infected with clustered genotypes and 47 (30%) were infected with the newly described "Midlands 1" (Md1) genotype. A further 18 patients were infected with the previously identified "Liverpool" genotype and two with the "Manchester" genotype. Logistic regression analysis revealed that the predominant predictor of infection with Md1 was age at the time of referral to the centre, suggesting that infection may have occurred prior to referral in some patients. Md1 demonstrated a relatively benign anti-biogram and did not appear to be associated with more severe disease. In conclusion, the present study provides further evidence of the emerging importance of Pseudomonas aeruginosa cross-infection in cystic fibrosis.
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PMID:Factors associated with infection by Pseudomonas aeruginosa in adult cystic fibrosis. 1620 96

Mucus obstruction of the airway in patients with cystic fibrosis (CF) reduces lung function, invites infection, and limits delivery of inhaled drugs including gene therapy vectors to target cells. Not all patients respond to presently available mucolytics, and new approaches are needed. Our objectives were to investigate the in vitro effects of unfractionated heparin (UFH) on the morphology and rheology of sputum and the effect of UFH on diffusion of 200-nm nanospheres through sputum from adult CF patients. Confocal laser scanning microscopy was used to image fluorescently stained actin and DNA components of CF sputum, and atomic force microscopy was used to image isolated DNA networks. The viscoelasticity of CF sputum was measured using dynamic oscillatory rheometry. Nanosphere diffusion was measured through CF sputum using a Boyden chamber-based assay. Actin-DNA bundles in CF sputum were disaggregated by UFH at concentrations of 0.1-10 mg/ml, and UFH enhanced the endonuclease activity in sputum from patients on dornase alfa therapy. UFH significantly reduced the elasticity and yield stress, but not the viscosity, of CF sputum from patients not receiving dornase alfa therapy. Heparin dose-dependently significantly increased the diffusion of nanospheres through CF sputum from patients not on dornase alfa therapy from 10.5 +/- 2.5% at baseline to 36.9 +/- 4.4% at 10 mg/ml but was more potent, with maximal effect at 0.1 mg/ml, in patients who were on dornase alfa therapy. Thus the mucoactive properties of UFH indicate its potential as a new therapeutic approach in patients with cystic fibrosis.
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PMID:Unfractionated heparin reduces the elasticity of sputum from patients with cystic fibrosis. 1782 52


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