restriction enzymes do not play a significant role in haemophilus homospecific or heterospecific transformation.competent haemophilus influenzae rd recipients, either as phage hp1 restricting (r+) or nonrestricting (r-) nonlysogens or defective lysogens, were exposed to deoxyribonucleic acids from various wild-type phage hp1 lysogenic h. influenzae serotype strains (non-encapsulated derivatives of serotypes a,b, c, d, and e), to dna from lysogenic haemophilus parahaemolyticus, and to dna from modified and nonmodified phage hp1. transformation of antibiotic resistance markers and of prophage markers in hom ...1976185196
on the nature of nontypable haemophilus influenzae.193 haemophilus cultures, including 71 nontypable h. influenzae isolates, were examined with respect to phage hp1 sensitivity, lysogeny for this and for other phages and for excretion of bacteriocins. fifty of the 71 nontypable cultures were sensitive to phage hp1 but only three produced plaques. the other 47 isolates were thus probably not non-encapsulated derivatives of h. influenzae serotypes a, b, d, and e, which have discrete and characteristic phage hp1 restriction and modification systems ...1978313183
fate of transforming bacteriophage hp1 deoxyribonucleic acid in haemophilus influenzae lysogens.the biological fate of temperate phage hp1 deoxyribonucleic acid (dna) was followed after uptake by defectively lysogenic competent haemophilus influenzae cultures. the similar inactivation kinetics of three single phage genetic markers and of their triple combination indicated a complete rather than partial destruction of about half of the adsorbed dna molecules. intracellular dna breakdown products were tentatively identified by hydroxyapatite column chromatography as short single strands and ...19751080148
site-specific integration of the haemophilus influenzae bacteriophage hp1: location of the boundaries of the phage attachment site.plasmids containing dna segments from the attachment region of phage hp1 were constructed and tested for the ability to replace the phage attachment site substrate in site-specific recombination reactions. the distance separating the boundaries of the functional site was 418 bp. replacements within the 11-residue segment 5'-ggcggttatcg at the left boundary or within the 12-residue segment 5'-ggattttttgaa at the right boundary abolished substrate activity. a segment of the 418-residue sequence pr ...19921383194
site-specific integration of the haemophilus influenzae bacteriophage hp1. identification of the points of recombinational strand exchange and the limits of the host attachment site.isotopic transfer experiments and boundary replacement studies were used to define the size and cleavage points of the haemophilus influenzae attb site for phage hp1 integration. the points of strand cleavage and transfer were separated by 5' extensions with a spacing or overlap region most probably 7 residues long. the complete hp1 attb site is included within an 18-base pair (bp) sequence surrounding the cleavage sites. the sequence of hp1 attb is remarkably symmetric. two 8-bp inverted repeat ...19921551893
interaction of integration host factor from escherichia coli with the integration region of the haemophilus influenzae bacteriophage hp1.the specific dna-binding protein integration host factor (ihf) of escherichia coli stimulates the site-specific recombination reaction between the attp site of bacteriophage hp1 and the attb site of its host, haemophilus influenzae, in vitro and also appears to regulate the expression of hp1 integrase. ihf interacts specifically with dna segments containing the att sites and the integrase regulatory region, as judged by ihf-dependent retardation of relevant dna fragments during gel electrophores ...19902203732
nucleotide sequence and expression of the gene for the site-specific integration protein from bacteriophage hp1 of haemophilus influenzae.the nucleotide sequence of the leftmost 2,363 base pairs of the hp1 genome, which includes the attachment site (attp) and the integration region, was determined. this sequence contained an open reading frame encoding a 337-residue polypeptide, which is a member of the integrase family of site-specific recombination proteins as judged by sequence comparison. the open reading frame was located immediately adjacent to the att site and was oriented so that initiation of translation would begin dista ...19892546915
site-specific recombination between cloned attp and attb sites from the haemophilus influenzae bacteriophage hp1 propagated in recombination-deficient escherichia coli.plasmids were constructed which contain both attp and attb dna segments derived from the insertion sites of the lysogenic bacteriophage hp1 and its host, haemophilus influenzae. similar plasmids containing the two junction segments (attl and attr regions) between the phage genome and the lysogenic host chromosome were also prepared. the formation of recombinant dimer plasmids was observed when attp-attb plasmids were propagated in escherichia coli hb101 (reca), while plasmids containing the junc ...19892646298
effect of glycerol on haemophilus influenzae transfection.competent haemophilus influenzae bacteria were exposed to purified phage hp1 dna and then plated for transfectants (pfu). when 32% (final concentration) glycerol was added before plating, between 10- and 100-fold more transfectants were observed. glycerol had no significant effect on transfection with dna from single or tandem double lysogens. it also had little effect on transformation with chromosomal dna or on transformation of defective hp1 lysogens with phage hp1 dna. it was concluded that ...19863485628
chromosomal recombination in haemophilus influenzae.haemophilus influenzae cultures doubly lysogenic for defective phage hp1, with a prophage marker sequence +b+/a+c, always contained some free wild-type phage. single ultraviolet-irradiated cells produced either no wild-type phage or large numbers of them. this suggested that the phage was not released by the original double lysogen but by internal recombinants, i.e., by double lysogens with altered prophage marker sequence such as +++/abc or +b+/++c. thirty-one wild-type phage-producing clones h ...19724538299
origin and direction of haemophilus bacteriophage hp1 dna replication.rapidly growing haemophilus influenzae strain rd bacteria were infected with bacteriophage hp1 and dna extracts prepared at various times thereafter. a number of phage genes scattered along the entire phage genome were quantitatively assayed by transformation. the kinetics of activity increases of these genes suggests that phage hp1 dna replication begins at a fixed origin about one-quarter from the right end and that it proceeds to the left.19744545061
acid-soluble breakdown of homologous deoxyribbonucleic acid adsorbed by haemophilus influenzae: its biological significance.competent bacteria of haemophilus influenzae strain rd were exposed to various kinds of radioactive deoxyribonucleic acid (dna) for short periods of time and at relatively low temperature. the fate of phage hp1 dna was studied most extensively. adsorbed dna was partially acid solubilized by lysogens and by nonlysogens with very similar kinetics. the biological activity of the dna decreased extensively in both lysogenic and nonlysogenic recipients. 2,4-dinitrophenol had no effect on the acid solu ...19744549063
influence of transformability on the formation of superinfection double lysogens in haemophilus influenzae.superinfection of growing (nontransformable) cells of defectively lysogenic strains of haemophilus influenzae with wild-type or with mutant phage hp1 resulted in a number of double lysogens and a small number of monolysogens with altered prophage. the double lysogens were identified by analysis of their monolysogenic segregants and by examining their deoxyribonucleic acid in certain test crosses. the results indicate that the majority had been formed by insertion of the infecting phage genome wi ...19715543425
repair of methyl methane sulfonate-damaged phage by haemophilus mutants of haemophilus influenzae strain rd (mmsa-) have been isolated that are more sensitive to methyl methane sulfonate (mms) than recombination-deficient (reca-) mutants. the mutations cotransformed about 25% with the stra locus while the five studied clustered tightly; they are all probably allelic. the mutants are not sensitive to ultraviolet radiation, x-rays, or nitrous acid. mms-damaged phage hp1 plated very inefficiently on these mutants, indicating that they lack the first step ...19836602266
addition, deletion, and substitution of long nonhomologous deoxyribonucleic acid segments by genetic transformation of haemophilus influenzae.a complete ecori digest of haemophilus influenzae phage hp1 deoxyribonucleic acid (dna) was mixed with incomplete digests of various h. influenzae r plasmids, sealed with t4 ligase, and transformed into an hp1 lysogen. most of the chloramphenicol- and tetracycline-resistant transformants did not produce phage although they possessed all the phage genes examined. they also did not transfer antibiotic resistance by conjugation. dna lysates from them transformed other lysogens to resistance and to ...19816975273
identification of an hp1 phage protein required for site-specific excision.transposon insertion mutagenesis and transformation were used to locate genes responsible for excision in the temperature phage hp1 of haemophilus influenzae. a 6.5 kb segment of dna near the left end of the phage genome was sequenced, and 11 new open reading frames were identified. two face-to-face overlapping promoter sequences organized these open reading frames into two operons transcribed in opposite directions. interruption of the first open reading frame in the rightward operon created ly ...19947997180
binding sites for bacteriophage hp1 integrase on its dna substrates.the temperate phage hp1 integrates its genome into the chromosome of haemophilus influenzae by site-specific recombination between host and phage dna segments, the attachment sites. this reaction is promoted by the hp1-encoded integrase. the interactions of hp1 integrase with its dna substrates have been characterized by dnase i footprinting. two classes of binding sites were identified. at sites of type i, integrase binding almost completely eliminated cleavage by dnase i; type i sites shared t ...19948063759
characterisation of a helicobacter pylori phage (hp1).the infection of two helicobacter pylori strains with a phage-containing supernate of the lysogenic h. pylori strain immi 290/89 resulted in a lytic cycle and propagation of phage hp1. in negatively-stained preparations, the empty phage heads measured 55-60 nm in diameter and mature heads measured 50 nm. the flexible, striated phage tail was c. 170 nm in length and 9.5 nm in diameter. the phage showed a mean density of 1.40 g/cm3 in sucrose-density gradients and contained double-stranded dna c. ...19938474115
determination of the cos sequence of the mature genome of s2/hp1 type b bacteriophage of haemophilus influenzae.the cos region of haemophilus influenzae phage hp1/s2 type b has been cloned and its nucleotide (nt) sequence determined. the nt sequence of the cohesive ends (cos) and whole cos site of type-b phage have been compared to corresponding sequences of the hp1c1 phage. the results of a search for symmetry elements and ihf-binding sites in this region are presented.19968654994
the complete nucleotide sequence of bacteriophage hp1 dna.the complete nucleotide sequence of the temperate phage hp1 of haemophilus influenzae was determined. the phage contains a linear, double-stranded genome of 32 355 nt with cohesive termini. statistical methods were used to identify 41 probable protein coding segments organized into five plausible transcriptional units. regions encoding proteins involved in recombination, replication, transcriptional control, host cell lysis and phage production were identified. the sizes of proteins in the matur ...19968710508
purification and characterization of the integrase from the haemophilus influenzae bacteriophage hp1; identification of a four-stranded intermediate and the order of strand exchange.the integrase encoded by the temperate phage hp1 promotes the site-specific recombination between dna sites on its genome (the attp site) and on the genome of the host haemophilus influenzae (the attb site). the protein has been overproduced in escherichia coli, and purified to apparent homogeneity. hp1 integrase promotes recombination of supercoiled attp-containing molecules with linear segments with attb sites. reaction was enhanced by spermidine and by the bacterial dna-bending protein integr ...19968843441
molecular organization in site-specific recombination: the catalytic domain of bacteriophage hp1 integrase at 2.7 a resolution.hp1 integrase promotes site-specific recombination of the hp1 genome into that of haemophilus influenzae. the isolated c-terminal domain (residues 165-337) of the protein interacts with the recombination site and contains the four catalytic residues conserved in the integrase family. this domain represents a novel fold consisting principally of well-packed alpha helices, a surface beta sheet, and an ordered 17-residue c-terminal tail. the conserved triad of basic residues and the active-site tyr ...19979108478
reciprocal regulation of the early promoter region of bacteriophage hp1 by the cox and cl proteins.we have identified a transcriptional switch at the early promoter region of bacteriophage hp1. this switch controls the transcription of the early lytic operon from the p(r1) and p(r2) promoters and the transcription of the lysogenic operon from the p(l) promoter. the start sites of the three promoters were mapped, and using a chloramphenicol acetyl transferase assay, we have investigated the levels of transcription from the promoters in the absence or in the presence of two phage-encoded transc ...19979268158
cloning of the dam methyltransferase gene from haemophilus influenzae bacteriophage hp1.the putative product of orf13 from the genome of haemophilus influenzae hp1 bacteriophage shows homology only to bacteriophage t1 dam methyltransferase, and a weak similarity to the conserved amino acids sequence motifs characteristic of m6a-methyltransferases. especially interesting is lack of characteristic motif i responsible for binding of s-adenosylmethionine. despite this fact, a dna sequence of hp1 bacteriophage of haemophilus influenzae encoding methyltransferase activity was cloned and ...199910581668
the amino terminus of bacteriophage lambda integrase is involved in protein-protein interactions during recombination.bacteriophage lambda integrase (int) catalyzes at least four site-specific recombination pathways between pairs of attachment (att) sites. protein-protein contacts between monomers of int are presumed to be important for these site-specific recombination events for several reasons: int binds to the att sites cooperatively, catalytic int mutants can complement each other for strand cleavage, and crystal structures for two other recombinases in the int family (cre from phage p1 and int from haemop ...200010648529
protein and dna requirements of the bacteriophage hp1 recombination system: a model for intasome formation.a fundamental step in site-specific recombination reactions involves the formation of properly arranged protein-dna structures termed intasomes. the contributions of various proteins and dna binding sites in the intasome determine not only whether recombination can occur, but also in which direction the reaction is likely to proceed and how fast the reaction will go. by mutating individual dna binding sites and observing the effects of various mixtures of recombination proteins on the mutated su ...200111574677
cloning of enterohemorrhagic escherichia coli phage vt-2 dam methyltransferase.enterobacterial gatc-specific dna adenine methyltransferase (dam) plays an essential role in regulation of dna replication, methyl-directed mismatch repair, transposition and gene expression. in salmonella typhimurium it has been shown to directly control virulence. in this paper we report cloning and expression of the dam gene from the shiga toxin-producing vt2-sa prophage of enterohemorrhagic escherichia coli o157. comparisons of the predicted amino acid sequence indicates that dam methyltrans ...200111720311
identification and characterization of genomic loci unique to the brazilian purpuric fever clonal group of h. influenzae biogroup aegyptius: functionality explored using meningococcal homology.brazilian purpuric fever (bpf) is a fulminant septicaemic infection of young children, caused by a clonal group of strains of haemophilus influenzae biogroup aegyptius (hae), an organism previously solely associated with conjunctivitis. their special capacity to invade from the initial site of conjunctival infection is unexplained. a polymerase chain reaction (pcr)-amplified subtractive hybridization technique was used to identify genes specific to the bpf clonal group. a copy of bacteriophage h ...200312581362
cloning and sequencing of a genomic island found in the brazilian purpuric fever clone of haemophilus influenzae biogroup aegyptius.a genomic island was identified in the haemophilus influenzae biogroup aegyptius brazilian purpuric fever (bpf) strain f3031. this island, which was also found in other bpf isolates, could not be detected in non-bpf biogroup aegyptius strains or in nontypeable or typeable h. influenzae strains, with the exception of a region present in the type b eagan strain. this 34,378-bp island is inserted, in reference to h. influenzae rd kw20, within a choline transport gene and contains a mosaic structure ...200515784532
dependence of vegetative recombination among haemophilus influenzae bacteriophage on the host cell.vegetative recombination of temperature-sensitive mutants of haemophilus influenzae phage hp1 cl was measured in wild-type h. influenzae strain rd and in strain db117, an ultraviolet-sensitive, transformation-defective mutant of the rd strain. recombinants are formed with low frequency in wild-type cells, but no recombination was detectable in db117. it is concluded that these phage make use of the host cell enzymes for vegetative recombination. lysogenization readily takes place in both strains ...196916789099
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