Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cistron A protein induced by phage varphiX174 nicks (produces a single-strand break in) the viral strand of the superhelical varphiX duplex DNA, thereby forming a complex with the DNA. The protein, seen bound to the DNA in the electron microscope, was located in the restriction endonuclease fragment between nucleotides 4290 and 4330 on the varphiX map [Sanger, F., Air, G. M., Barrel, B. G., Brown, N. L., Coulson, A. R., Fiddes, J. C., Hutchison, C. A., III, Slocomb, P. M. Y. & Smith, M. (1977) Nature 265, 687-695]. Replication also was initiated at this point, thus identifying the site of cistron A protein nicking and binding as the origin of replication. The cisA-DNA complex (separated from free cistron A protein), upon the addition of Escherichia coli rep protein, ATP, and DNA binding protein, is unwound to generate a single-stranded linear [presumably the nicked (+) strand] and a circular [presumably the (-) strand] molecule. The cisA-DNA complex, upon the further addition of DNA polymerase III holoenzyme and deoxynucleoside triphosphates, supports replication to generate viral, single-stranded circles, as many as 15 circles per cisA-DNA complex. The replicating intermediates seen in the electron microscope are a novel form of "rolling circle" [Gilbert, W. & Dressler, D. H. (1969) Cold Spring Harbor Symp. Quant. Biol. 33, 473-485]. The 5' end (presumably with the cistron A protein bound to it) is locked in the replication fork and loops back to accompany the strand-separation and replication fork around the template [(-) strand] circle. Thus, the multiple functions of cistron A protein include: (i) nicking the viral strand at the origin of replication to initiate a round of replication, (ii) participating in a complex which supports fork movement in strand separation and replication, (iii) nicking again at the regenerated origin to produce a unit-length DNA, and (iv) ligating the newly generated 3'-OH end to the 5'-phosphate-complexed end to form a circular viral molecule.
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PMID:phiX174 cistron A protein is a multifunctional enzyme in DNA replication. 26 83

Recombinant DNAs containing the E. coli plasmid pSC101 and mouse cell (La9) mitochondrial DNA (mtDNA) were formed in vitro via ligation of DNA fragments from limit EcoRI endonuclease digests and were used to transform E. coli K12. Four structurally different recombinant plasmid DNAs from transformed clones were characterized. Two of these were analyzed extensively and the mtDNA portions compared with mtDNA from LA9 cells. No differences were detected in the physical or chemical properties examined, except that the E. coli mtDNA lacked the alkali lability characteristic of animal mtDNAs. Heteroduplexes between the LA9 portions of the recombinant plasmids and LA9 mtDNA were analyzed by absorbance melting. The melting temperatures were indistinguishable from reannealed LA9 mtDNA homoduplexes, indicating that single-base replication errors occur at a frequency of fewer than 1 nucleotide in 300. Electron microscopic analyses of plasmid-LA9 mtDNA heteroduplexes and a comparison of agarose gel electrophoresis of restriction endonuclease fragments also indicated no differences. These results were independent of the order or the relative orientation of the pSC101 and mtDNA fragments. A third EcoRI fragment in LA9 mtDNA, not found in an earlier study (Brown and Vinograd, 1974), has been positioned in the LA9, EcoRI map. This fragment contains 165+/-10 nucleotide pairs.
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PMID:The structures and fidelity of replication of mouse mitochondrial DNA-pSC 101 EcoRI recombinant plasmids grown in E. coli K12. 78 20

A full-length genomic clone for human tyrosine hydroxylase (L-tyrosine, tetrahydropteridine:oxygen oxidoreductase, EC 1.14.16.2) has been isolated. A human brain genomic library constructed in EMBL3 was screened by using a rat cDNA for tyrosine hydroxylase as a probe [Brown, E. R., Coker, G. T., III, & O'Malley, K. L. (1987) Biochemistry 26, 5208-5212]. Out of one million recombinant phage, one clone was identified that hybridized to both 5' and 3' rat cDNA probes. Restriction endonuclease mapping. Southern blotting, and sequence analysis revealed that, like its rodent counterpart, the human gene is single copy, contains 13 primary exons, and spans approximately 8 kilobases (kb). In contrast to the rat gene, human tyrosine hydroxylase undergoes alternative RNA processing within intron 1, generating at least three distinct mRNAs. A comparison of the human tyrosine hydroxylase and phenylalanine hydroxylase [DiLella, A. G., Kwok, S. C. M., Ledley, F. D., Marvit, J., & Woo, S. L. C. (1986) Biochemistry 25, 743-749] genes indicates that although both probably evolved from a common ancestral gene, major changes in the size of introns have occurred since their divergence.
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PMID:Isolation and characterization of the human tyrosine hydroxylase gene: identification of 5' alternative splice sites responsible for multiple mRNAs. 289 28

A method is described which allows a large number of bacterial strains to be rapidly and easily screened for the presence of site-specific endonucleases. The method involves selective permeabilization of the bacterial cell and analysis of the exuded material. Type II restriction endonucleases from cyanobacteria and Gram-negative eubacteria have been detected and new enzymes have been found. The method should be widely applicable and easy to modify for use in genera other than those tested. Three-site-specific endonuclease activities, detected by this method in Aphanothece halophytica PCC 7412, were purified and their recognition and cleavage specificities were determined AhaI and AhaII recognise and cleave the same DNA sequences as CauII and AcyI respectively; the specificity of AhaIII (TTT decreases AAA) has been reported previously (Whitehead and Brown, 1982, FEBS Letters 143:296-300).
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PMID:A simple and rapid method for screening bacteria for type II restriction endonucleases: enzymes in Aphanothece halophytica. 298 68

Seven loci of endogenous proviruses were detected in the genome of Brown Leghorn chickens. Sets of endogenous proviruses in DNA of the chicken embryos examined were identified by blot hybridization with 32P-labelled DNA of RSV and EcoRI restriction endonuclease digestion. Comparison of the results showed that only one locus (A) of endogeneous provirus was associated with a gs+ phenotype as determined by the immunoperoxidase reaction and antibodies against gag gene products of RSV. Restriction endonuclease analysis with HindIII, BamHI and SacI revealed that proviruses A and F in Brown Leghorn chickens correspond to loci ev-3 and ev-6, respectively, in White Leghorn chickens. Other loci (B, C, D, E, and X) were designated ev-22, ev-23, ev-24, ev-25, ev-26, respectively. None of these loci expressed infectious virions. The structure of most of the endogenous proviruses examined is considerably different from the genome of the endogenous chicken virus RAV-O. The difference in structure may be one possible cause of the absence of endogenous provirus expression.
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PMID:Genetic structure of the endogenous proviruses and expression of the gag gene in Brown Leghorn chickens. 300 39

Among the 7 endogenous proviruses we have detected in Brown Leghorn chickens none encodes the production of virions and only one, ev-3, expresses the gag gene. To study the possible role of DNA methylation in the inhibition of provirus expression, we performed blot hybridization and restriction endonuclease analysis with EcoRI and SmaI, is sensitive to methylation. Of the six endogenous proviral loci examined (ev-3, ev-6,, ev-22, ev-23, ev-24, ev-25), two loci, ev-23 and ev-24, were methylated at all SmaI restriction sites, in both the DNA from erythrocytes of adult chickens and the DNA from 10-day embryos. Since both these viruses are closely related to the genome of RAV-O, DNA methylation might be the cause of the absence of gene expression.
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PMID:Methylation of endogenous proviruses of Brown Leghorn chickens. 300 40

Partially replicated bacteriophage T4 DNA containing cytosine was isolated from cells 6.5 and 7 min after infection and cleaved with restriction endonuclease BglII or BamHI. Positions of replication eyes relative to the cleavage sites were observed by electron microscopy. Four groups of eyes were found. They are consistent with replication from origins located at map positions 34, 60, 73, and 86 kilobases. In individual molecules that contained two or three eyes, the distribution of the eyes agreed with the initiation of replication at more than one of these four assigned origins and possibly at two additional origins located near 15 and 110 kilobases, which were reported by P. M. Macdonald, R. M. Seaby, W. Brown, and G. Mosig (p. 111-116, in D. Schlessinger, ed., Microbiology--1983, 1983) and M. E. Halpern, T. Mattson, and A. W. Kozinski (Proc. Natl. Acad. Sci. U.S.A. 76:6137-6141, 1979).
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PMID:Locations of bacteriophage T4 origins of replication. 398 6

The free energy of the binding reaction between EcoRI restriction endonuclease and a specific cognate dodecadeoxynucleotide (d(CGCGAATTCGCG)) has contributions from both electrostatic and nonelectrostatic components. These contributions were dissected by measuring the effects of varying salt concentration on the equilibrium binding constant and applying the thermodynamic analyses of Record et al. (Record, M. T., Jr., Lohman, T. M., and deHaseth, P. L. (1976) J. Mol. Biol. 107, 145-158). Endonuclease mutation S187 (Arg 187 to Ser) (Greene, P. J., Gupta, M., Boyer, H. W., Brown, W. E., and Rosenberg, J. M. (1981) J. Biol. Chem. 256, 2143-2153) did not significantly affect the nonelectrostatic component but did perturb the electrostatic contribution to the binding energy (we are numbering the amino acid residues according to the DNA sequence). The former was determined by extrapolating the linear portion of the salt dependence curve (0.125 to 0.25 M KCl) to 1 M ionic strength, with the same result for both wild type and S187 endonucleases at both pH 6.0 and 7.4 (-8.5 +/- 1.5 kcal/mol or greater than 50% of the total binding free energy). The slopes of these same curves yield estimates of eight ionic interactions between wild type endonuclease and the DNA at both pH values. By contrast, binding of EcoRI-S187 to dodecanucleotide involves six charge-charge interactions at pH 6.0. Only two ionic interactions are observed at pH 7.4. This was unexpected since gel permeation chromatography demonstrated that the recognition complex for both wild type and S187 proteins contains an enzyme dimer and a DNA duplex. EcoRI-S187 endonuclease retains wild type DNA sequence specificity, and the rate of the phosphodiester hydrolysis step is also unchanged. Thus, electrostatic interactions are functionally separable from sequence recognition and strand cleavage. Our results also establish that arginine 187 plays a key role in the electrostatic function and suggest that it might be located at the DNA-protein interface. The disproportionate loss of ion pairs at pH 7.4 can be rationalized by a model which suggests that six conformationally mobile ionic groups on the protein act in a coordinated manner during the interaction with DNA.
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PMID:Coordinate ion pair formation between EcoRI endonuclease and DNA. 631 32

The type II restriction endonuclease EcoRV was crystallized as a complex with the substrate DNA undecamer AAAGATATCTT (recognition sequence underlined). These crystals diffract to much better resolution (2 A) than was the case for the previously reported complex with the decamer GGGATATCCC [Winkler, F. K., Banner, D. W., Oefner, C., Tsernoglou, D., Brown, R. S., Heathman, S. P., Bryan, R. K., Martin, P. D., Petratos, K., & Wilson, K. S. (1993) EMBO J. 12, 1781-1795]. The crystal structure contains one dimer complex in the asymmetric unit and was solved by molecular replacement. The same kinked DNA conformation characteristic for enzyme-bound cognate DNA is observed. Crystals, soaked with Mg2+, show the essential cofactor bound at only one active site of the dimer, and the DNA is not cleaved. The Mg2+ has one oxygen from the scissile phosphodiester group and two carboxylate oxygens, one form Asp74 and one from Asp90, in its octahedral ligand sphere. The scissile phosphodiester group is pulled by 1 A toward the Mg2+. After substrate cleavage in solution, isomorphous crystals containing the enzyme--product--Mg2+ complex were obtained. In this structure, each of the 5'-phosphate groups is bound to two Mg2+. The kinked DNA conformation is essentially maintained, but the two central adenines, 3' to the cleavage sites, form an unusual cross-strand base stacking. The structures have been refined to R factors of 0.16 at 2.1-2.0 A resolution maintaining very good stereochemistry. On the basis of these structures and inspired by recent kinetic data [Vipond, I. B., & Halford, S. E. (1994) Biochemistry (second paper of three in this issue)], we have constructed a transition state model with two metals bound to the scissile phosphorane group.
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PMID:Mg2+ binding to the active site of EcoRV endonuclease: a crystallographic study of complexes with substrate and product DNA at 2 A resolution. 781 64

The amino acid sequence of bovine somatotropin (bST) varies at position 127 where either valine or leucine is found. The frequencies of leucine127 and valine127 bST gene alleles in cows (n = 302) and sires (n = 70) from major dairy breeds (Holstein, Brown Swiss, Guernsey, Jersey, and Ayrshire) were determined using DNA extracted from whole blood or spermatozoa. A 428 base pair fragment of the bST gene was amplified using polymerase chain reaction (PCR) and variants of the bST gene were detected as polymorphisms by Alu I restriction endonuclease digestion of PCR products. Restriction enzyme DNA fragments for the leucine127 variant were 265, 96, 51, and 16 base pair and for the valine127 variant were 265, 147, and 16 base pair as a polymorphism of bST was present in the 147 base pair DNA fragment. Frequencies of leucine127 and valine127 alleles for cows (n = 302) were 1.0 and 0 for Brown Swiss, .93 and .07 for Holstein, .92 and .08 for Guernsey, .79 and .21 for Ayrshire, and .56 and .44 for Jersey, respectively. In Holstein sires used for artificial insemination (n = 70), the frequency of leucine127 and valine127 alleles was .96 and .04. Estimates of transmitting ability for milk production tended to be greater for Holstein cows that were homozygous for leucine127 bST and Jersey cows that were homozygous for valine127 bST whereas Holstein sires with different bST genotypes were similar. In summary, frequencies of alleles for the bST gene were not similar in different dairy breeds and estimates of milk production were correlated with bST gene variant in cows but not sires.
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PMID:Variants of somatotropin in cattle: gene frequencies in major dairy breeds and associated milk production. 790 13


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