Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolates of virus from the brain tissue of two naturally occurring cases of progressive multifocal leukoencephalopathy in rhesus monkeys (Macaca mulatta) have been characterized. Both isolates were demonstrated to be simian virus 40 (SV40) by serological tests and analysis of cleavage fragments of viral deoxyribonucleic acid produced by restriction endonuclease from Haemophilus influenzae. SV40 virions and the nonvirion T antigen were demonstrated in the brain lesions of one monkey by the fluorescent antibody staining technique. SV40 was not demonstrated in the brain of normal rhesus monkeys from the same colony with use of the same methods of viral isolation or demonstration of antigen.
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PMID:Isolation of simian virus 40 from rhesus monkeys (Macaca mulatta) with spontaneous progressive multifocal leukoencephalopathy. 19 89

Fouteen "flush"-ended segments originate from the action of the restriction endonuclease Hae III of Haemophilus aegiptius on the DNA of the colicinogenic factor ColE 1 (A. Oka and M. Takanami, Nature, 264, 191, 1976). They are joined by the T4 polynucleotide ligase. The reaction can be monitored by gel electrophoresis, electron microscopy and resistance to phosphatase of the 5'-32P labelled ends. The joined products are a random recombination of the original segments, and can be cleaved by the same Hae III endonuclease to restore the exact electrophoretic pattern of the Hae III-cut ColE 1 DNA. In a properly diluted mixture of 5'-32P segments treated with T4 ligase, the level of phosphatase resistance is very close to the frequency of circle-formation as determined by electron microscopy: thus, the joining of the "flush"-ends involves the formation of circular structures covalently closed in both strands.
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PMID:Restoration by T4 ligase of DNA sequences sensitive to "flush" cleaving restriction enzyme. 19 43

In a first part of this report, purification and characterization of several nucleased from lysates of Haemophilus influenzae are described. The enzymes bind to DNA with agarose columns and are removed by elution with phosphate buffer. Among the considered enzymes, the exonucleases 1 and 3, and endonuclease, a DNA polymerase and a restriction enzyme were recovered mixed by raising the phosphate concentration from 0.1 to 0.3 M, while the ATP-dependent DNAase recovered well purified, by raising the phosphate concentration to 0.45 M. After a rechromatography, on a second DNA with agarose column, of the peak of the ATP-dependent DNAase, the specific activity tested with 3H-labeled DNA was 125 units/mg of protein, representing a 300-fold purification of the original crude extract. In a second part, we have investigated the inactivation, at various pH, of transforming DNA of Haemophilus influenzae wild strain Rd with the different eluted fractions of the column, in order to determine the importance of contamination with other enzymatic activities, and also in order to confirm the nature of theisolated enzymes with a biological method. Finally, with enzymatic extracts of mutant strain Rd com minus 56, a strain which integrates shorter than normal pieces of DNA and which is suspected to possess and "activated specific endonuclease" able to recognize even small conformational modifications in paired structures, we tried to detect this activity on artificially constructed heteroduplex regions in DNA.
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PMID:Studies on deoxyribonucleases from Haemophilus influenzae on DNA agarose affinity chromatography. Two-step purification of ATP-dependent deoxyribonuclease. 23 41

The nucleotide sequences in the replicative form (duplex) of phiX174 DNA around six sites cut by Hga I, a restriction endonuclease from Haemophilus gallinarum, have been compared. The enzyme produces a staggered cleavage resulting in a pentanucleotide 5'-terminal extension. The sequences within and immediately surrounding the pentanucleotide cleavage site have no obvious relationship. However, the sequence 5'-G-A-C-G-C-3' 3'-C-T-G-C-G-5' occurs five nucleotide pairs to the left of the cut in the upper strand and 10 nucleotide pairs to the left of the cut in the lower strand and, therefore, is believed to constitute the recognition site. This is a member of the class of restriction endonucleases in which recognition and cleavage sites lack 2-fold rotational symmetry. The method used to define the cleavage site is of general applicability.
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PMID:Cleavage specificity of the restriction endonuclease isolated from Haemophilus gallinarum (Hga I). 26 84

We have determined the nucleotide sequence of a Hpa II restriction fragment of the phage T7 DNA containing a promoter for the phage-specified RNA polymerase. (Hpa II is a restriction endonuclease from Haemophilus parainfluenzae.) Mapping of the Hpa II restriction fragments on the T7 genome shows this promoter to be the second of tandem promoters separated by approximately 170 base pairs that begin transcription by the T7 RNA polymerase at approximately 15% of the genome. Features of the sequence involved in recognition by the T7 RNA polymerase are discussed and include the following region of hyphenated 2-fold symmetry (boxed regions are related through a 2-fold axis of symmetry at the center of the sequence shown). (See article). This sequence includes the initiation site, since the message transcribed from this fragment begins pppG-G-G-A. Combination of our results with work of others has permitted this fragment to be mapped at the junction of T7 genes 1 and 1.1. The RNA transcribed from this fragment begins within gene 1 and contains the RNase III cleavage site that lies between genes 1 and 1.1. This sequence is compared to other processing sites in T7 early message.
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PMID:Structure of a promoter for T7 RNA polymerase. 27 Jun 69

An endonuclease purified from Hemophilus influenzae made single strand breaks in DNA containing apurinic or apyrimidinic sites but had no detectable endonuclease activity on untreated native DNA. The new 5'-termini created at the cleavage sites were base-free deoxyribose 5-phosphate residues. The enzyme preparation also catalyzed the exonucleolytic release of 5'-mononucleotides from bihelical DNA and the hydrolysis of DNA 3'-terminal phosphomonoesters. The phosphatase-exonuclease activity was indistinguishable from that reported by Gunther and Goodgal (J. Biol. Chem. (1970) 245, 5341-5349) and resembled that of exonuclease III of Escherichia coli. The endonucleolytic and exonucleolytic activities could not be separated by electrophoresis, sedimentation, or gel filtration, and they were also affected simultaneously by mutation. The enzymatic activities appear to be functions of a single monomeric protein (M(r) = 30,000).
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PMID:A DNase for apurinic/apyrimidinic sites associated with exonuclease III of Hemophilus influenzae. 30 19

Haemophilus cells efficiently take up Haemophilus DNA from the medium during transformation but do not take up other DNAs. To study the mechanism of this specificity we have cloned an 8.1-kilobase (kb) fragment of H. parainfluenzae DNA in the escherichia coli--pBR322 host--vector system and reisolated the DNA fragment for use as a defined probe. The 5'32P end-labeled 8.1-kb DNA is efficiently absorbed by competent Haemophilus cells whereas vector DNA present in the mixture is not, implying that the 8.1-kb DNA contains sequence-specific recognition sites that are needed for DNA uptake. Absorbed DNA can be recovered from cells as a 32P-labeled duplex of unaltered size for several minutes after uptake. We have determined the number and location of uptake sites in the 8.1-kb DNA by constructing a restriction endonuclease cleavage map and assaying fragments for uptake. Only two small fragments retain the ability to be absorbed. These fragments, 120 and 140 base pairs long, are 3.8 kb apart on the 8.1-kb fragment. We assume that each of these fragments contains a short common sequence, perhaps 8--12 base pairs long, that is the actual recognition site. We have shown by DNA competition assays, with the 8.1-kb DNA as a standard, that about 600 copies of the uptake sites are present in the Haemophilus genome.
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PMID:Sequence-specific DNA uptake in Haemophilus transformation. 31 78

The genes for a Class II restriction-modification system (HhaII) from Haemophilus haemolyticus have been cloned in Escherichia coli. The vector used for cloning was plasmid pBR322 which confers resistance to tetracycline and ampicillin and contains a single endonuclease R-PstI site, (formula: see text), in the ampicillin gene. The procedure developed by Bolivar et al. (1977) was used to form DNA recombinants. H. haemolyticus DNA was cleaved with PstI endonuclease and poly(dC) extensions were added to the 3'-OH termini using terminal deoxynucleotidyl transferase. Circular pBR322 DNA was cleaved to linear molecules with PstI endonuclease and poly(dG) extensions were added to the 3'-OH termini, thus regenerating the PstI cleavage site sequences. Recombinant molecules, formed by annealing the two DNAs, were used to transfect a restriction and modification-deficient strain of E. coli (HB101 r-m-recA). Tetracycline-resistant clones were tested for acquisition of restriction phenotype (as measured by growth on plates seeded with phage lambdacI-0). A single phage-resistant clone was found. The recombinant plasmid, pD110, isolated from this clone, had acquired 3 kilobases of additional DNA which could be excised with PstI endonuclease. In addition to the restriction function, cells carrying the plasmid expressed the HhaII modification function. Both activities have been partially purified by single-stranded DNA-agarose chromatography. The cloned HhaII restriction activity yields cleavage patterns identical to HinfI. A restriction map of the cloned DNA segment is presented.
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PMID:Cloning of restriction and modification genes in E. coli: the HbaII system from Haemophilus haemolyticus. 35 Jul 14

The interaction of bacteriophage T7 specific RNA polymerase with its cognate promoter sites has been probed by selectively replacing bases in one T7 promoter site with base analogs. Base analogs such as 2,6-diaminopurine or hypoxanthine, which alter residues appearing in the minor groove of the DNA helix, prevent utilization of the promoter by T7 RNA polymerase. These analogs do not affect transcription which starts outside of the modified region. In contrast, base analogs that have alterations that appear in the major groove of the DNA helix, such as uracil, 5-bromouracil, 5-methylcytosine, 5-hydroxymethylcytosine, and [5-HgSR]pyrimidines, do not prevent utilization of the promoter. The deoxyribonucleoside analog 5'-imino-5'-deoxythymidine, an alteration appearing in the deoxyribose-phosphodiester backbone of the DNA helix, does not prevent promoter recognition. Haemophilus aegyptius restriction endonuclease III, which cleaves DNA at the sequence 5'GGCC3', does not act at sites in which the guanine residues in one of the two DNA strands have been substituted with hypoxanthine. This implicates the guanine amino group in the minor groove of the DNA helix as a possible recognition point for this restriction endonuclease.
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PMID:Transcription of T7 DNA containing modified nucleotides by bacteriophage T7 specific RNA polymerase. 35 45

A new restriction endonuclease has been isolated from Bacillus sphaericus R. The purification procedure includes Bio-Gel filtration, (NH4)2SO4 fractionation and phosphocellulose chromatography. After the phosphocellulose step the enzyme preparation is free of non-specific nucleases. Bsp cleaves double-stranded DNA with the same specificity as Bacillus subtilis (Bsu) and Haemophilus aegyptius (HaeIII) restriction endonucleases, as concluded from digests and double-digests of phiX174 replicative form DNA with Bsu and Bsp. The 5'-terminal nucleotide of the cleavage products was shown to be C. Bacillus sphaericus R produces Bsp in extremely large quantities and the enzyme can be easily purified in high yield.
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PMID:A new sequence-specific endonuclease (Bsp) from Bacillus sphaericus. 59 Jul 42


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