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)

Replicative form DNA of bacteriophage fd, which had been fragmented with the restriction endonuclease II from Hemophilus parainfluenzae (endo R- HpaII), was reacted with Escherichia coli RNA polymerase; the resulting stable preinitiation complexes were analysed using the filter binding assay followed by gel electrophoresis. At 120mM KCL the first-order rate constants for complex decay were determined to be 10(-2)-10(-6)s-1. The second-order rate constants for complex formation were found to be about 10(6) -10(7) M-1 s-1. From these values association constants for the individual promoters were calculated to be 2 x 10(-8) -2 x 10(-11) M-1. The rate of formation and the stability of promoter complexes was enhanced in superhelical DNA. No evidence was found for stable promoter-specific closed complexes consisting of enzyme and helical DNA. This and the kinetic data suggest that the unwinding of base pairs is already important early in promoter selection, and not only for the formation of the final open complex. The initiation of RNA synthesis form the preinitiation complex was faster than complex dissociation and complex formation for all promoters. Consequently, the initiation efficiency of a promoter is determined by the rate of complex formation, and not by its 'affinity' for the enzyme. No correlation was found between the relative order of the fd promoters for the binding and the dissociation reaction. This is explained by different structural determinants, for the two reactions, which are located in different parts of the promoter DNA.
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PMID:Interaction of RNA polymerase with promoters from bacteriophage fd. 30 Jun 80

The inactivation of bacteriophage HP1c1 by X rays in a complex medium was found to be exponential, with a D0 (the X-ray exposure necessary to reduce the survival of the phage to 37%) of approximately 90 kR. Analysis of results of sucrose sedimentation of DNA from X-irradiated whole phage showed that the D0 for intactness of single strands was about 105kR, and for intactness of double strands, it was much higher. The D0 for attachment of X-irradiated phage to the host was roughly estimated as about 1,100 kR. Loss of DNA from the phage occurred and was probably due to lysis of the phage by X irradiation, but the significance of the damage is not clear. The production of single-strand breaks approaches the rate of survival loss after X irradiation. However, single-strand breaks produced by UV irradiation, in the presence of H2O2, equivalent to 215 kR of X rays, showed no lethal effect on the phage. Although UV-sensitive mutants of the host cell, Haemophilus influenzae, have been shown to reactivate UV-irradiated phage less than does the wild-type host cell, X-irradiated phage survive equally well on the mutants as on the wild type, a fact suggesting that other repair systems are involved in X-ray repair.
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PMID:Effects of x irradiation on a temperate bacteriophage of Haemophilus influenzae. 30 Aug 11

Tetracycline resistance in a strain of Haemophilus influenzae isolated in the United Kingdom was found to be determined by an apparently non-selftransmissible plasmid of 31 X 10(6) daltons (31 MDal), designated pUB701. Deoxyribonucleic acid hybridization studies indicated that pUB701 shares about 70% base sequence homology with the 30-MDal ampicillin resistance R plasmid RSF007 isolated in the United States from H. influenzae, and 64% sequence homology with the 38-MDal tetracycline and chloramphenicol resistance R plasmid pRI234, isolated in the Netherlands. Heteroduplex studies between RSF007 and pUB701 confirmed the fact that these plasmids were largely homologous, except that pUB701 contained the tetracycline resistance transposon TnD, whereas RSF007 contained the ampicillin resistance transposon TnA. A strain of H. parainfluenzae resistant to both chloramphenicol and tetracycline carried two species of plasmid deoxyribonucleic acid of 2.7 and 0.75 MDal. We were unable to prove that either resistance was plasmid-borne in this strain. Hybridization studies with a [3H]thymine-labeled tetracycline resistance enteric plasmid suggested that the tetracycline transposon was integrated into the chromosome of H. parainfluenzae UB2832. We conclude either that the strains we studied received R factors of the same incompatibility group bearing different resistance genes, or that different resistance genes were translocated to a commom resident plasmid of H. influenzae.
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PMID:Relationships among some R plasmids found in Haemophilus influenzae. 30 23

Attempts were made to induce mutations in Haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine. These attempts were unsuccessful. Incorporation studies with BrdUrd showed, in agreement with earlier studies on Escherichia coli, that BrdUrd was discriminated against when dThd was also present but was incorporated to essentially the same extent as dThd when only BrdUrd was present. In this latter case, strands fully substituted with BrdUrd was produced, but survival data suggest that bacteria deriving their DNA by replication on such fully substituted templates were inviable. However, bacteria with about 20% of the thymine substituted with bromouracil were usually viable. No mutations could be detected in the descendants of such bacteria. The reasons for this are discussed and it is concluded that in all probability the replication system in species rarely if every treats incorporated bromouracil as anything except a thymine analogue. The alternative possibility, that the negative results are a consequence of the absence of the reclex (SOS) error-prone repair system in this species, is considered much less likely.
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PMID:Attempts to induce mutations in Haemophilus influenzae with the base analogues 5-bromodeoxyuridine and 2-aminopurine. 30 11

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

N-Methyl-N'-nitrosoguanidine (MNNG) causes reversion of a temperature-sensitive mutation in a bacteriophage of Haemophilus influenzae if exposure to the mutagen takes place after infection but before lysis. However, neither pre-infection treatment of the phage DNA, host cells, or both will cause reversion. The reasons for this are discussed in relation to the somewhat different results in the Escherichia coli lambda phage system and in relation to error-prone repair and replication processes.
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PMID:Evidence against the reversion of mutation in the Haemophilus influenzae phage HP1c1 by preinfection treatment of host cells or phage with MNNG. 30 62

When competent Haemophilus influenzae were returned to complete growth medium, they resumed growth at once and underwent a synchronous division after 20 to 25 min. The rate of DNA synthesis increased to the definitive rate very quickly after resumption of growth. In contrast, the rate of RNA synthesis remained low until the time of division, at which time it accelerated dramatically. Changes in the rate of protein synthesis were similar in form to those of RNA synthesis. The kinetics of loss of competence upon resumption of growth had a pattern similar to the rate of RNA synthesis, and both processes accelerated markedly at the time of cell division, suggesting an inverse relationship between RNA synthesis and the ability to take up DNA.
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PMID:Synchronous division and rates of macromolecular synthesis in Haemophilus influenzae competent for genetic transformation. 30 8

Thirty bacterial species were tested for their ability to stimulate to increased DNA synthesis in human blood lymphocytes. A definite stimulation was obtained with eighteen bacterial species. For three of these species ten different strains of each were tested, and all increased DNA synthesis. The maximum response was after 3--4 days of culture, suggesting a mitogenic effect. This was confirmed by the induction of polyclonal antibody production shown by a plague assay, which was positive for nine of eleven species tested. Most bacterial species increased the DNA synthesis in B-lymphocyte-enriched and unseparated lymphocytes but had negligible activity on T-lymphocyte-enriched cultures. Among bacteria with a mitogenic effect and ability to induce polyclonal antibody production are Staphylococcus aureus strain Cowan I with a high content of protein A and many common human pathogens such as Haemophilus influenzae, Mycobacterium tuberculosis, Neisseria gonorrhoeae, Streptococcus group A and Streptococcus pneumoniae.
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PMID:Many bacterial species are mitogenic for human blood B lymphocytes. 30 29

Studies were carried out on the repair and fixation of premutational damage induced in Haemophilus influenzae by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). The studies employed a temperature-sensitive DNA elongation mutant (dna9) and its combinations with mutants defective in pyrimidine dimer excision (uvr1, uvr2) and in recombination (rec1). The dna9 mutant is shown to be leaky, allowing about 1% of the normal rate of DNA synthesis at the restrictive temperature. Repair of premutational lesions was detected by a decline in mutation frequency with increasing delay in DNA replication in dna9 at the restrictive temperature. This repair is unaffected by the pyrimidine dimer excision system. Mutation fixation was detected by the ability of DNA from treated and then lysed cells to transfer mutants to recipient cells by transformation. Some fixation occurred at the restrictive temperature but much less than at the non-restrictive temperature suggesting that an appreciable minority of the mutations resulted from lesions introduced near the replication fork but that the majority of mutations arise from lesions introduced at some distance from the fork, perhaps randomly. The DNA synthesized immediately after MNNG treatment is of lower molecular weight than normal and returns to normal with time. This return is blocked in the rec1 mutant, suggesting that recombination is involved. The possible role of this process in MNNG mutagenesis is discussed.
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PMID:The role of pre-replication and post-replication processes in mutation induction in Haemophilus influenzae by N-methyl-N'-nitro-N-nitrosoguanidine. 31 May 10

The accessibility of DNA in nucleosome dimers (as a model of the chromosomal chain of nucleosomes) was determined by means of modification methylases from Haemophilus influenzae Rd. Using these enzymes, the rate of modification of nucleosome dimers is about one fifth the rate observed with protein-free DNA from chromatin subunit dimers. Methylated DNA sites in nucleosome dimers are readily accessible to micrococcal nuclease. The analysis of the fragment pattern of nucleosomes after methylation and mild nuclease treatment reveals that the methylated sites are predominantly located in the internucleosomal linker DNA. Polylysine binding experiments further support this interpretation. This compound preferentially interacts with the nucleosomal core DNA and protects it against internal cleavage. It neither affects the degradation of methylated sites drastically nor does it inhibit the methylation of nucleosome dimers. Thus, a combination of protection, cleavage and modification is proposed as a useful tool for the analysis of the structure of chromatin.
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PMID:Modification of DNA in chromatin with methyltransferase from Haemophilus influenzae Rd. 31 Dec 84


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