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)

The mitochondrial DNA segments of two independently isolated rho- clones of S. cerevisiae carrying a genetic marker for a threonine tRNA have been characterized by restriction endonuclease analysis and DNA sequencing. The DNA sequences of the two segments have been used to deduce the primary and secondary structures of the tRNA. The threonine tRNA is unusual in having a leucine anticodon (3'-GAU-5'). Despite the anomalous anticodon, the tRNA is proposed to function in mitochondrial protein synthesis. One of the rho- clones contains an additional coding sequence that has been identified as a valine tRNA genes have been located on the wild-type physical map and determined to be transcribed from two different strands.
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PMID:Assembly of the mitochondrial membrane system: sequences of yeast mitochondrial valine and an unusual threonine tRNA gene. 38 33

Escherichia coli DNA with molecular weight of 20 - 10(6) daltons was digested by restriction endonuclease EcoR1, and the transforming activity of resctricts was studied. The transforming activity of restricts for two markers (Leu and Arg) was 2-5 fold increased, for two other markers (Thr and His) was not changed, and for one marker (Pro) was completely absent. The molecular weight of E. coli DNA restricts was 7,5-10(6) daltons. An increase and a decrease of the transforming activity for different markers appeared to be the result of two effects: 1) more efficient uptake of low molecular weight DNA into the cell and 2) the inactivation of markers as a result of location close to EcoR1 induced break.
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PMID:[Transforming activity of Escherichia coli DNA fragments obtained following endonucleolytic splitting by EcoRI restrictase]. 79 31

A group of patients with prealbumin associated hyperthyroxinemia possess a common single base substitution in the fourth exon of their transthyretin gene. This cytosine to thymine substitution occurs in the codon for residue 119 and results in the predicted replacement of a threonine residue with a methionine at this position. A new NcoI restriction endonuclease cleavage site is created by the point mutation and can be detected by a rapid and simple assay based on the polymerase chain reaction. This variant transthyretin is inherited in an autosomal dominant manner and is apparently not amyloidogenic but is associated with increased thyroxine binding. As healthy heterozygous individuals have normal serum thyroxine concentrations, the hyperthyroxinemia sometimes found may not be primarily due to the variant.
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PMID:A novel variant of transthyretin (prealbumin), Thr119 to Met, associated with increased thyroxine binding. 135 51

Infantile-onset glycogen storage disease type II, or Pompe disease, results from a genetic deficiency of the lysosomal enzyme acid alpha glucosidase (GAA). Sequencing of the cDNA from a cell line (GM 244) derived from a patient with Pompe disease demonstrated a T953-to-C transition that predicted a methionine-to-threonine substitution at codon 318. The basepair substitution resulted in loss of restriction-endonuclease sites for NcoI and StyI. Analysis of genomic DNA revealed both a normal and an abnormal NcoI fragment, indicating that the patient was a genetic compound. NcoI and StyI digestion of cDNA, amplified by PCR from reverse-transcribed RNA, demonstrated that greater than 95% of the GAA mRNA in GM 244 was derived from the allele carrying the missense mutation. The missense mutation was uncommon, since it was not detected in 37 additional GAA-deficient chromosomes, as determined by digestion of genomic DNA with NcoI and hybridization. The amino acid substitution predicts a new potential site for N-linked glycosylation, as well as major changes in secondary structure of the protein. We could confirm that the mutation was responsible for the enzyme deficiency by demonstrating that a hybrid minigene containing the mutation did not express GAA enzyme activity after transient gene expression. We have therefore now provided the first identification of a single-basepair missense mutation in a patient with Pompe disease and furthermore have demonstrated that the patient is a genetic compound with the second allele barely expressing mRNA.
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PMID:Identification of a missense mutation in one allele of a patient with Pompe disease, and use of endonuclease digestion of PCR-amplified RNA to demonstrate lack of mRNA expression from the second allele. 165 92

Plasma von Willebrand factor (vWf) is a multi-domain multimerized glycoprotein which has a dual role in haemostasis: it promotes platelet adhesion to subendothelium and is the carrier of blood coagulation factor VIII (FVIII). We previously characterized a functional defect of vWf, limited to its ability to bind FVIII, in two families whose affected members have the same phenotype that mimics mild haemophilia A and was tentatively named von Willebrand's disease (vWD) 'Normandy'. A homozygous point mutation C----T converting Thr 28 to Met in mature vWf subunit was identified in one of these patients who was born of third-cousin parents. In the present studies we report two unrelated new cases of vWD 'Normandy' and characterize, using the analysis of the vWf gene intron 40 region containing a variable number of tandem repeats, the recessive inheritance of the disease in two affected families without known consanguinity. Exons 18-24 of the vWf gene encoding for the first 311 amino acids of mature vWf subunit were amplified by the polymerase chain reaction method and sequenced. Two new missense mutations, both corresponding to a C----T transition and predicting respectively an Arg 53----Trp and an Arg 91----Gln substitution, were characterized. The three patients from family 1 were homozygous for the first-mentioned mutation while the patient from family 3 was homozygous for the second. The patient from family 2 was found a compound heterozygote for the two mutations. None of the two point mutations reported, both destroying a MspI restriction site, could be detected in DNA from 50 normal controls screened by restriction endonuclease analysis. Our data show that different mutations may be found in patients with the 'Normandy' phenotype. The mutations characterized so far are all localized on the N-terminal region of mature vWf subunit, within or near the major FVIII binding domain, and some of them occur within the epitope of monoclonal antibodies inhibiting the vWf/FVIII interaction. These observations suggest a causal relationship between these mutations and the vWD 'Normandy' phenotype.
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PMID:Identification of two point mutations in the von Willebrand factor gene of three families with the 'Normandy' variant of von Willebrand disease. 183 34

A library of mutant ecoRIR genes encoding EcoRI restriction endonuclease was generated using trinucleotide blocks and a combination of recombinant DNA procedures, including primer extension and the polymerase chain reaction. Codons corresponding to three amino acids (E144, R145 and R200), previously implicated in the specific recognition of the DNA substrate, were combinatorially mutated so as to generate a library that potentially contains all 20(3) possible single, double and triple aa replacements, in a balanced distribution. Inspection of the phenotypes of Escherichia coli colonies bearing the mutant genes showed that several of them retained activities that were deleterious to the cells but were still protected by the EcoRI methyltransferase. These included new enzyme variants, including non-conservative single (Thr or Val for Glu144) and double (Val for Glu144 and Thr for Arg145) replacements.
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PMID:Combinatorial mutagenesis of three major groove-contacting residues of EcoRI: single and double amino acid replacements retaining methyltransferase-sensitive activities. 193 43

The gene coding for plasminogen has been compared with several abnormal genes from Japanese patients by the polymerase chain reaction and DNA sequence analysis. Two types of abnormal genes coding for plasminogen were identified in these patients. In the type I mutation, a guanosine in GCT coding for Ala-601 near the active-site histidine was replaced by an adenosine resulting in ACT coding for threonine. This mutation was also shown by the loss of a cleavage site for Fnu4HI endonuclease, a restriction enzyme that recognizes GCTGC but not ACTGC. In the type II mutation, a guanosine in GTC coding for Val-355 was replaced by a thymidine resulting in TTC coding for phenylalanine. This change was readily shown by digestion with Ava II endonuclease, a restriction enzyme that recognizes GGTCC and not GTTCC. The type I mutation has been found to be identical to a plasminogen variant identified in Japanese patients by amino acid sequence analysis and also detected by isoelectric focusing, whereas the type II mutation is a unique amino acid substitution in the connecting region between the third and fourth kringles in plasminogen. DNA sequence analysis also revealed that the abnormal genes carry several silent nucleotide substitutions located primarily within introns and 5' and 3' flanking regions.
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PMID:Two types of abnormal genes for plasminogen in families with a predisposition for thrombosis. 198 55

T4 endonuclease V is a pyrimidine dimer-specific DNA repair enzyme which has been previously shown not to require metal ions for either of its two catalytic activities or its DNA binding function by virtue of its ability to function in the presence of metal-chelating agents. However, we have investigated whether the single cysteine within the enzyme was able to bind metal salts and influence the various activities of this repair enzyme. A series of metals (Hg2+, Ag+, Cu+) were shown to inactivate both endonuclease Vs pyrimidine dimer-specific DNA glycosylase activity and the subsequent apurinic nicking activity. The binding of metal to endonuclease V did not interfere with nontarget DNA scanning or pyrimidine dimer-specific binding. The Cys-78 codon within the endonuclease V gene was changed by oligonucleotide site-directed mutagenesis to Thr-78 and Ser-78 in order to determine whether the native cysteine was directly involved in the enzyme's DNA catalytic activities and whether the cysteine was primarily responsible for the metal binding. The mutant enzymes were able to confer enhanced ultraviolet light (UV) resistance to DNA repair-deficient Escherichia coli at levels equal to that conferred by the wild type enzyme. The C78T mutant enzyme was purified to homogeneity and shown to be catalytically active on pyrimidine dimer-containing DNA. The catalytic activities of the C78T mutant enzyme were demonstrated to be unaffected by the addition of Hg2+ or Ag+ at concentrations 1000-fold greater than that required to inhibit the wild type enzyme. These data suggest that the cysteine is not required for enzyme activity but that the binding of certain metals to that amino acid block DNA incision by either preventing a conformational change in the enzyme after it has bound to a pyrimidine dimer or sterically interfering with the active site residue's accessibility to the pyrimidine dimer.
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PMID:Selective metal binding to Cys-78 within endonuclease V causes an inhibition of catalytic activities without altering nontarget and target DNA binding. 203 8

An apolipoprotein (apo) B-specific monoclonal antibody, MB19, detects a commonly occurring two-allele genetic polymorphism in human apoB (Young, S. G., S. J. Bertics, L. K. Curtiss, D. C. Casal, and J. L. Witztum. 1986. Proc. Natl. Acad. Sci. USA. 83: 1101-1105). Antibody MB19 binds to two different allotypes of apoB, MB19(1) and MB19(2), with high and low affinity, respectively. The epitope for antibody MB19 is located within apoB-100 thrombolytic fragment T4 (apoB-100 amino acid residues 1-1297). In this study, we examined the relationship of the MB19 polymorphism to a C----T nucleotide substitution at apoB cDNA nucleotide 421. This nucleotide substitution results in a Thr----Ile substitution at apoB-100 amino acid 71, and it changes an ApaLI restriction endonuclease site in the apoB gene. The nucleotide substitution was easily detectable by ApaLI digestion of a 141-base pair fragment of the apoB gene obtained by enzymatic amplification of genomic DNA. In 62 subjects, the MB19 phenotype, as determined by radioimmunoassays, correlated perfectly with the ApaLI restriction site polymorphism in the amplified DNA. The apoB allotype MB19(1) is associated with an Ile at residue 71 and the absence of the ApaLI site, whereas the apoB allotype MB19(2) is associated with a Thr at residue 71 and the presence of the ApaLI site. We conclude that the amino acid substitution at residue 71 probably accounts for the MB19 polymorphism in apoB.
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PMID:An ApaLI restriction site polymorphism is associated with the MB19 polymorphism in apolipoprotein B. 247 Aug 48

A lambda gt11 cDNA library, prepared from porcine submaxillary gland mRNA, was screened with anti-apomucin IgG, and five antibody-reactive phage were isolated. The phage with the largest cDNA insert, designated lambda PSM103, was further characterized. Its fusion protein reacted with anti-apomucin IgG and was used to affinity purify antibodies that specifically reacted with apomucin, indicating that the protein shares antigenic determinants with apomucin. The nucleotide sequence of 1510 bases in the 3.7-kilobase cDNA insert of lambda PSM103 has been established, thereby giving a deduced amino acid sequence of 503 residues in apomucin, or about 45% of the molecule. The deduced sequence of the apomucin polypeptide was found to contain 4.8 tandemly repeated, identical sequences of 81 residues each. The presence of these uniquely repeated sequences was confirmed by restriction endonuclease digestion of DNA derived from lambda PSM103. The repeat sequence was also confirmed in apomucin by the isolation of an 81-residue tryptic peptide with an amino acid composition and an amino-terminal amino acid sequence (up to 44 residues) identical to those of the tandem repeat. Moreover, the peptide was isolated in 760% yield, indicating that the tandem repeat occurs at least eight times in apomucin. The presence of such a long repetitive region in the gene for apomucin raises the possibility for considerable polymorphism in the gene and a corresponding size heterogeneity of apomucin. The predicted secondary structure of the 503 residues confirms the earlier proposal that apomucin is an extended, nonglobular polypeptide. Although the sequences around 192 serine and threonine residues have been established in apomucin, a recognition sequence for the N-acetylgalactosaminyltransferase that initiates glycosylation of apomucin is not evident, except that the glycosylated residues occur in turns.
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PMID:Porcine submaxillary gland apomucin contains tandemly repeated, identical sequences of 81 residues. 282 55


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