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 major conclusion from these studies is that variants of Haemophilus influenzae Rd which restrict and modify phage S2 are metastable and capable of giving rise to one another with high frequency. Nonrestrictive RdS cells segregate spontaneously to the restricting, modifying phenotype in about 5% of the progeny of a single clone. The restrictive cells derived from RdS revert to the nonrestrictive phenotype in 15 to 25% of the progeny of a single clone. These frequencies are not appreciably affected by treatment with acriflavine or ethidium bromide, compounds which affect plasmid stability, or by nitrosoguanidine, a powerful mutagen. The genetic locus for restriction and modification of bacteriophage S2 is found to have a chromosomal position between the biotin and proline loci. Restriction-modification of phage S2 has been shown to be a function of its deoxyribonucleic acid (DNA) in that transfection with S2 phage DNA or prophage DNA is subject to host restriction and modification. An enzyme preparation, which contains endodeoxyribonuclease but no appreciable exonuclease activity, from mutant H. influenzae com(-10) did not restrict phage S2.RdS DNA or prophage DNA transfecting activity, indicating that this endodeoxyribonuclease is not responsible for phage restriction. A new restriction enzyme isolated from H. influenzae Rd was found to be the major enzyme involved in the restriction of bacteriophage S2. The enzyme inactivated the transfecting activity of unmodified phage DNA but did not attack modified phage DNA. Unlike endodeoxyribonuclease R, this enzyme requires adenosine triphosphate and S-adenosylmethionine.
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PMID:Restriction and modification of bacteriophage S2 in Haemophilus influenzae. 414 62

An enzyme similar to that described by Smith and Wilcox (15) for Haemophilus influenzae which attacks foreign deoxyribonucleic acid (DNA) but not its own has been isolated and purified from H. parainfluenzae. The enzyme degrades foreign DNA to limited sizes and can destroy the transforming activity of H. influenzae and Bacillus subtilis DNA. The enzyme can also destroy the biological activity of H. influenzae phage and prophage DNA. On the other hand, the H. influenzae endodeoxyribonuclease can destroy the transforming activity of H. parainfluenzae DNA but not its own DNA. It also attacks B. subtilis DNA and its transforming activity.
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PMID:Action of haemophilus endodeoxyribonuclease on biologically active deoxyribonucleic acid. 433 66

Hemophilus parainfluenzae endodeoxyribonuclease was used to degrade the DNA of H. influenzae and to follow the biological activity of 14 markers associated with this DNA. It was found that some H. influenzae markers were completely inactivated by endodeoxyribonuclease treatment, while others appeared to retain all or almost all of their original activity. The bulk of the H. influenzae DNA was reduced to double-stranded pieces of the order of 8 x 10(5) to 1 x 10(6) daltons. Velocity sedimentation of the DNA in sucrose gradients disclosed that markers that retained biological activity were present in DNA particles that were of the order of 1 x 10(6) daltons or larger, and indicated a close correlation between the size of the DNA fragment and the amount of biological activity retained. These data suggest that H. parainfluenzae endodeoxyribonuclease breaks DNA at specific sites. The nal(r) marker was shown to have twice as much biological activity after treatment with endodeoxyribonuclease when assayed at saturating DNA concentrations. In the linear portion of the DNA dose-response curve, the biological activity of this marker was reduced 3- to 10-fold compared to untreated DNA (in accord with the reduced size of its DNA). These data demonstrate a specific enrichment of the nal(r) marker by about 6- to 20-fold, and suggest a technique for the separation and purification of specific segments of DNA.
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PMID:Separation of specific segments of transforming DNA after treatment with endodeoxyribonuclease. 463 56