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)

The ATP-dependent DNase from Hemophilus influenzae digests double-stranded linear DNA molecules exonucleolytically while hydrolyzing large amounts of ATP to ADP. Various cross-linked linear duplex DNA molecules are partially resistant to the exonuclease action. Vaccinia DNA, containing natural terminal cross-links (probably in the form of terminal single-stranded loops), is much more slowly degraded than comparable "open-ended" DNA molecules, and ATP is consumed at a proportionately lower rate. It is postulated that the vaccinia DNA molecules undergo slow terminal cleavage by the single strand specific endonuclease activity of the enzyme, and are then rapidly degraded by the double strand exonuclease activity. Phage T7 DNA, containing an average of 100 4',5'8-trimethylpsoralen cross-links/molecule at random internal sites, is digested only to the extent of 2 to 3%. However, ATP hydrolysis continues at a linear rate long after DNA digestion has ceased. A stable enzyme-DNA complex is formed as demonstrated by co-sedimentation of DNA and ATPase activity in sucrose gradients. The hypothesis is advanced that the enzyme digests exonucleolytically to the first cross-link at each end of the DNA molecules where further movement is prevented. The enzyme then remains bound at the cross-links and functions continuously as an ATPase.
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PMID:Action of ATP-dependent DNase from Hemophilus influenzae on cross-linked DNA molecules. 13 99

By a direct assay approach, mutants of Haemophilus influenzae Rd that are deficient in adenosine 5'-triphosphate-dependent deoxyribonuclease activity (add-) were isolated and characterized. A large proportion (50 to 90%) of the cells in cultures of these mutants failed to produce visible colonies when plated. An extensive analysis of the recombination proficiency of these strains revealed that the transformation frequency (transformants per competent cell) in the mutants was similar to that found in the wild type, but that the transformation efficiency (transformants per microgram of irreversibly bound deoxyribonucleic acid [DNA]) was reduced approximately fourfold. Sensitivities of the mutants to gamma rays, ultraviolet radiation, and methyl methane sulfonate were only slightly greater than wild-type levels. The rate of degradation of host DNA after ultraviolet irradiation was significantly reduced in the mutants. It is suggested that the adenosine 5'-triphosphate-dependent deoxyribonuclease in H. influenzae plays a nonessential role in DNA recombination and repair.
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PMID:Isolation and characterization of mutants of Haemophilus influenzae deficient in an adenosine 5'-triphosphate-dependent deoxyribonuclease activity. 16 69

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

A number of ampicillin-resistant strains of Haemophilus influenzae could donate a gene specifying the type IIIa (TEM) beta-lactamase to Haemophilus parainfluenzae, Escherichia coli, and Pseudomonas aeruginosa. Donor strains rapidly lost their ability to transfer ampicillin resistance on storage or subculture. Such strains also apparently contained a single species of covalently closed circular deoxyribonucleic acid of contour length 1.2 mum, equivalent to about 2.5 x 10(6) daltons. No species of plasmid deoxyribonucleic acid large enough to encode sex factor activity was detected. Despite this, transfer occurred to several bacterial genera in the presence of deoxyribonuclease, suggesting that transmissibility was by conjugation. The beta-lactamase gene was generally unstable after transfer and was lost in the absence of selection. Where stable transcipients were found, this was evidently by insertion of the beta-lactamase gene into the host chromosome. In P. aeruginosa insertion was always accompanied by induction of auxotrophy for adenine, suggesting insertion at a specific site. It is believed that insertion also occurred at one site on the chromosome of Escherichia coli. Crypticity measurements for beta-lactamase activity showed that there was little or no penetration barrier to beta-lactam drugs in Haemophilus. This may explain the long delay in the acquisition of ampicillin resistance by this organism.
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PMID:Transfer of a plasmid-specified beta-lactamase gene from Haemophilus influenzae. 40 56

Using a membrane filter assay, we have studied the binding reaction between the ATP-dependent DNase from Hemophilus influenzae and duplex DNA under conditions where the degradative reaction is not allowed to proceed. Experiments with three forms of SV40 DNA. Complex formation between enzyme and DNA requires neither DNA or enzyme concentration is fixed while the other is varied reveal that binding is noncooperative and that there are two binding sites per linear DNA molecule. These binding sites probably correspond to the two termini of the molecule.
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PMID:Binding of the ATP-dependent DNase from Hemophilus influenzae to duplex DNA molecules. 82 58

During bacteriophage studies on Haemophilus influenzer, it was observed that encapsulated type b and unencapsulated Rb strains released a bactericidal substance acitve against types a, c, d, e, and f H. influenzae, non-typable H. influenzae strains, other Haemophilus species, and certain members of the Enterobacteriaceae. The bactericidal activity was assayed by a plaque test utilizing an Rd strain as an indicator lawn and was also demonstrated in mixed broth cultures of a producer strain and an indicator strain. Immediately lysis of sensitive bacteria by the factor was not evident. The factor is sensitive to trypsin but resistant to deoxyribonuclease, treatment with 2-mercaptoethanol, lipase, alpha-amylase, and heating in a 100 degrees C water bath for 20 min. The activity is not dependent upon increased Ca2+ or Mg2+ concentration as is necessary for HP1C1 and S2 phage propagation. The bactericidal factor is not pelleted by high-speed centrifugation at 150,000 X g for 6 h. Treatment with ultraviolet light or mitomycin C does not result in observable phage, phage-like particles, or increased bactericidal activity. T-HE BACTERICIDAL FACTOR IS NOT A TYPICAL SMALL MOLECULAR WEIGHT "COLICIN-LIKE" BACTERiocin in that it is not inducible, has a wider range of activity, and does not kill by "single-hit" kinetics. On preliminary characterization, it is a thermostable protein toxic to certain bacterial strains.
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PMID:Bactericidal substance produced by Haemophilus influenzae b. 108 28

A type I restriction enzyme from Haemophilus influenzae, Hind I, which requires adenosine 5' -triphosphate and 5-adenosyl methionine, was studied for its activity on transfecting and transforming deoxyribonculeic acid (DNA). The enzyme reduced the size of unmodified bacteriophage S2 DNA from 37 X 10(6) daltons to approximately 10 X 10(6) daltons, but did not affect modified S2 DNA. Unmodified transforming DNA was attacked in vitro by Hind I; however, relatively low levels of inactivation were obtained for single markers, and linked transformants were inactivated as a function of the distance between markers. In contrast, unmodified bacterial DNA was not inactivated in vivo for either single or linked markers by the Hind I restriction system, probably because the segments generated by Hind I were still capable of being integrated in vivo. The lack of preferential inactivation of markers by the enzyme suggests that it makes random breaks in the DNA.
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PMID:Biological properties of a Haemophilus influenzae restriction enzyme, Hind I. 108 99

A transformation-deficient strain of Haemophilus influenzae, lacking adenosine 5'-triphosphate-dependent deoxyribonuclease activity, was isolated by selection for sensitivity to mitomycin. The mutant, designated JK57, possibily showed a moderate sensitivity to ultraviolet (UV) irradiation and treatment with methyl methane sulfonate. Contrary to the wild type, the mutant degraded chromosomal deoxyribonucleic acid (DNA) to some extent. However, after UV irradiation to the mutant degraded considerably less DNA than the wild type and the TD24 mutant of H. influenzae, the latter being equivalent to a recA mutant of Escherichia coli. A TD2457 double mutant, constructed by transferring the TD24 mutation into the JK57 strain, was as sensitive to deleterious agents and as deficient in transformation as the TD24 single mutant; in the double mutant, however, after UV irradiation chromosomal DNA was degraded to the same extent as in the JK57 mutant. The number of transformants per unit of radioactive donor DNA taken up by JK57 recipient cells was approximately 10-fold smaller than in the wild type. Presynaptically, the fate of donor DNA in the adenosine 5'-triphosphate-dependent deoxyribonuclease-deficient mutants was not different from that in the wild type. In contrast to TD24 and the TD2457 double mutant, in the JK57 mutant, recombinant-type activities (molecules carrying both the donor and recipient markers) were formed almost as well as in the wild type. After integration into the JK57 recipient genome, the rate of replication of the donor marker was equal to that of the recipient marker during a number of generations, which suggests that the donor DNA is normally integrated into the JK57 chromosome. It is suggested that transformed JK57 cells pass with a high frequency into a type of cells that can replicate their chromosomes many times but have lost the ability to form visible colonies after plating.
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PMID:Effect of adenosine 5'-triphosphate-dependent deoxyribonuclease deficiency on properties and transformation of Haemophilus influenzae strains. 108 3

The genes from Haemophilus parainfluenzae encoding the HpaI restriction-modification system were cloned and expressed in Escherichia coli. From the DNA sequence, we predicted the HpaI endonuclease (R.HpaI) to have 254 amino acid residues (Mr 29,630) and the HpaI methyltransferase (M.HpaI) to have 314 amino acid residues (37,390). The R.HpaI and M.HpaI genes overlapped by 16 base pairs on the chromosomal DNA. The genes had the same orientation. The clone, named E. coli HB101-HPA2, overproduced R.HpaI. R.HpaI activity from the clone was 100-fold that from H. parainfluenzae. The amino acid sequence of M.HpaI was compared with those of other type II methyltransferases.
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PMID:Cloning and expression of the HpaI restriction-modification genes. 154 67

A DNA fragment of about 3.4 kilobase pairs that expressed the HgaI modification activity was cloned from the chromosomal DNA of Haemophilus gallinarum, and its nucleotide sequence was determined. Two open reading frames (ORF) which could code for structurally similar proteins were identified in the upstream and middle regions and a truncated ORF in the downstream region in the same orientation. When the respective ORFs were separately cloned, the clones carrying the upstream and middle ORFs both expressed the modification activity, indicating that the two genes are involved in modification of the HgaI restriction-modification system. In order to determine the sites of modification precisely, the respective genes were recloned into an expression vector, from which gene products were purified. A short DNA fragment carrying the HgaI recognition site was treated with each of these enzymes, and, after separation of the two strands by duplex formation with M13 viral DNAs carrying the respective strands, the presence or absence of modification was judged from susceptibility to HgaI endonuclease. The results of analysis showed that different strands were modified in an asymmetric way by each gene product. Analysis of the species and positions of modified bases by the Maxam-Gilbert method further demonstrated that the gene products from the upstream and middle ORFs participated in methylation of the internal cytosine residues of the strands carrying 3'-CTGCG-5' and 5'-GACGC-3', respectively. We concluded that the HgaI modification system consisted of two cytosine methylase genes responsible for modification of different strands in the target DNA.
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PMID:The HgaI restriction-modification system contains two cytosine methylase genes responsible for modification of different DNA strands. 185 24


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