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)

Genetic transformation of bacterial cells required the induction of a state of competence to bind and absorb free DNA molecules. Induction of competence in Haemophilus influenzae was accompanied by the generation on the cell surface of membrane extensions ("blebs") 80 to 100 nm in diameter. When competent cells were returned to normal growth conditions, they shed these structures as free vesicles with a concomitant loss of cellular DNA-binding activity. Purified vesicle preparations retained the ability to bind double-stranded DNA in a nuclease-resistant, salt-stable form. Binding was specific for DNA molecules containing the 11-base pair Haemophilus uptake sequence, required Na+ and divalent cations (Mg2+, Ca2+, or Mn2+), and was inhibited by the presence of EDTA or high concentrations of salt (greater than 0.5 M NaCl). Binding was not stimulated by nucleotide triphosphates and was insensitive to the uncoupling agents dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. Vesicles contained the major Haemophilus outer membrane proteins and were enriched in several minor proteins.
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PMID:Generation and release of DNA-binding vesicles by Haemophilus influenzae during induction and loss of competence. 698 66

The P2 protein from pathogenic Haemophilus influenzae type b (Hib) functions as a bacterial porin and is one of several immunogenic outer membrane proteins. The P2 gene was expressed in Escherichia coli and the recombinant P2 protein (re-P2) purified to facilitate functional and immunologic studies. P2 was obtained from Hib strain Eagan using PCR and the pET vectors (17b and 11a) were used to produce re-P2 at levels exceeding 30% of the total E. coli proteins. Since previous reports had indicated that P2 was toxic to E. coli, steps were taken to control the toxicity. The plasmid was stabilized by tightly controlling the synthesis of re-P2 prior to induction. Subsequent to induction, re-P2 was sequestered into inclusion bodies rather than to membrane compartments. The refolding of the denatured re-P2 into the trimeric form involved high salt and calcium ions. re-P2 was then purified to homogeneity using gel-filtration and ion-exchange chromatography.
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PMID:Production of Haemophilus influenzae type-b porin in Escherichia coli and its folding into the trimeric form. 782 34

Mannan-binding protein (MBP), a calcium-dependent plasma lectin, may play a role in the innate defence against microorganisms. After binding to carbohydrate structures at the bacterial surface, MBP activates the classical pathway of the complement system. To investigate the binding capacity of MBP to various bacteria associated with meningitis, an assay was developed to study the binding of MBP to bacteria grown in a semisynthetic fluid culture medium. Salmonella montevideo (containing a mannose-rich lipopolysaccharide (LPS)), used as a positive control strain, showed binding of radiolabelled MBP at a level of 80% compared with binding of MBP to zymosan. Binding of labelled MBP to Salm. montevideo was time-dependent, temperature-dependent and saturable. The binding was inhibited by unlabelled MBP, by mannose and by N-acetyl-D-glucosamine. Among bacterial pathogens often found to cause meningitis, a wide range of MBP binding capacities could be determined. The encapsulated Neisseria meningitidis (representatives from 11 serogroups other than group A were included: n = 22), N. mucosa (n = 1), Haemophilus influenzae type b (n = 10) and Streptococcus agalactiae (n = 5) had a low MBP binding capacity of 21.7% (95% confidence interval (CI) 3.3-40.1%). Escherichia coli K1 (n = 11), Strep. suis (n = 5), Strep. pneumoniae (n = 10) and N. meningitidis serogroup A (n = 2) showed intermediate MBP binding capacity of 58.4% (95% CI 40.0-76.8%). A third group consisting of non-encapsulated Listeria monocytogenes (n = 11), non-encapsulated H. influenzae (n = 2), non-encapsulated N. meningitidis (n = 2), N. cinera (n = 1) and N. subflava (n = 1) strains had a high MBP binding capacity of 87.5% (95% CI 62.5-112.5%). The majority of encapsulated pathogens causing bacterial meningitis seem to have a rather low MBP binding capacity.
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PMID:Binding of mannan-binding protein to various bacterial pathogens of meningitis. 808 95

A 0.972-kilobase pair DNA fragment from Streptomyces lividans that induces the production of the blue-pigmented antibiotic actinorhodine in S. lividans when cloned on a multicopy plasmid has led to the isolation of a 4-kilobase pair DNA fragment from Streptomyces coelicolor containing homologous sequence. Computer-assisted analysis of the DNA sequence revealed three putative open reading frames (ORFs), ORF1, ORF2, and ORF3. ORF2 extends beyond the sequenced DNA fragment, and its deduced product shares no similarities with any other known proteins in the data bases. ORF3 is also truncated, and its 41-amino acid C-terminal product is identical to the S. coelicolor adenine phosphoribosyltransferase. The 847-amino acid ORF1 protein, with a predicted molecular mass of 94.2 kDa, strongly resembled the relA and spoT gene products from Escherichia coli and the homologs from Vibrio sp. strain S14, Haemophilus influenzae, Streptococcus equisimilis H46A, and Mycoplasma genitalium. Unlike these proteins, the ORF1 amino acid sequence analysis revealed the presence of a putative ATP/GTP-binding domain. A mutant was generated by deleting most of the ORF1 gene that showed an actinorhodine-nonproducing phenotype, while undecylprodigiosin and the calcium-dependent antibiotic were unaffected. The mutant strain grew at a much lower rate than the wild-type strain, and spore formation was delayed. When the gene was propagated on a low copy number vector, not only was actinorhodine production restored, but actinorhodine and undecylprodigiosin production was enhanced in both the mutant and wild-type and morphological differentiation returned to wild-type characteristics. (p)ppGpp synthetase activity was not detected in purified ribosomes from the ORF1-deleted mutant, while it was restored by complementation of this strain.
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PMID:A relA/spoT homologous gene from Streptomyces coelicolor A3(2) controls antibiotic biosynthetic genes. 863 67

In Escherichia coli, flavodoxin is the physiological electron donor for the reductive activation of the enzymes pyruvate formate-lyase, anaerobic ribonucleotide reductase, and B12-dependent methionine synthase. As a basis for studies of the interactions of flavodoxin with methionine synthase, crystal structures of orthorhombic and trigonal forms of oxidized recombinant flavodoxin from E. coli have been determined. The orthorhombic form (space group P2(1)2(1)2(1), a = 126.4, b = 41.10, c = 69.15 A, with two molecules per asymmetric unit) was solved initially by molecular replacement at a resolution of 3.0 A, using coordinates from the structure of the flavodoxin from Synechococcus PCC 7942 (Anacystis nidulans). Data extending to 1.8-A resolution were collected at 140 K and the structure was refined to an Rwork of 0.196 and an Rfree of 0.250 for reflections with I > 0. The final model contains 3,224 non-hydrogen atoms per asymmetric unit, including 62 flavin mononucleotide (FMN) atoms, 354 water molecules, four calcium ions, four sodium ions, two chloride ions, and two Bis-Tris buffer molecules. The structure of the protein in the trigonal form (space group P312, a = 78.83, c = 52.07 A) was solved by molecular replacement using the coordinates from the orthorhombic structure, and was refined with all data from 10.0 to 2.6 A (R = 0.191; Rfree = 0.249). The sequence Tyr 58-Tyr 59, in a bend near the FMN, has so far been found only in the flavodoxins from E. coli and Haemophilus influenzae, and may be important in interactions of flavodoxin with its partners in activation reactions. The tyrosine residues in this bend are influenced by intermolecular contacts and adopt different orientations in the two crystal forms. Structural comparisons with flavodoxins from Synechococcus PCC 7942 and Anaebaena PCC 7120 suggest other residues that may also be critical for recognition by methionine synthase.
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PMID:A flavodoxin that is required for enzyme activation: the structure of oxidized flavodoxin from Escherichia coli at 1.8 A resolution. 941 2

A natural calpain activator protein has been isolated from bovine brain and characterized in its properties and molecular structure. The protein is a homodimer with a molecular mass of about 30 kDa and results in being almost identical to UK114 goat liver protein. Significant similarities with mouse HR12 protein were also observed, whereas a lower degree of similarity was found with a family of heat-responsive proteins named YJGF and YABJ from Haemophilus influenzae and Bacillus subtilis, respectively. The brain activator expresses a strict specificity for the mu-calpain isoform, being completely ineffective on the m-calpain form. As expected, also UK114 was found to possess calpain-activating properties, indistinguishable from those of bovine brain activator. A protein showing the same calpain-activating activity has been also isolated from human red cells, indicating that this factor is widely expressed. All these activators are efficient on mu-calpain independently from the source of the proteinase. The high degree of specificity of the calpain activator for a single calpain isoform may be relevant for the understanding of sophisticated intracellular mechanisms underlying intracellular proteolysis. These data are indicating the existence of a new component of the Ca2+-dependent proteolytic system, constituted of members of a chaperonin-like protein family and capable of promoting intracellular calpain activation.
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PMID:Molecular and functional properties of a calpain activator protein specific for mu-isoforms. 958 10

Surfactant protein (SP)-D is an oligomeric glycoprotein belonging to the family of collagen-like lectins known as collectins, which have previously been shown to stimulate phagocytosis and other immune cell functions. The hypothesis investigated in this study was that SP-D would stimulate the phagocytosis of an important pulmonary pathogen, Pseudomonas aeruginosa. SP-D, isolated from the lavage fluid of silica-treated rats, significantly enhanced the uptake of three of six strains of P. aeruginosa by rat alveolar macrophages as analyzed by both fluorescence and electron microscopy. SP-D had only minimal effects on phagocytosis of Haemophilus influenzae. SP-D bound to live P. aeruginosa, and binding was inhibited by chelation of calcium and by a competing saccharide, inositol. In vitro killing assays demonstrated that macrophage-mediated killing of one of the mucoid strains of P. aeruginosa was modestly enhanced by SP-D. P. aeruginosa was not measurably aggregated by SP-D either macroscopically or microscopically. Further, SP-D does not appear to act as an activation ligand because adherence of macrophages to SP-D- coated slides did not stimulate the uptake of P. aeruginosa. These findings suggest that SP-D may be important in controlling the pathogenesis of P. aeruginosa in the lung.
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PMID:Surfactant protein D stimulates phagocytosis of Pseudomonas aeruginosa by alveolar macrophages. 1053 13

Non-typeable Haemophilus influenzae (NTHi) invades host cells by binding of the platelet-activating factor (PAF) receptor via lipooligosaccharide (LOS) glycoforms containing phosphorylcholine (ChoP). The effect of NTHi infection on host cell signalling and its role in NTHi invasion was examined. The infection of human bronchial epithelial cells with NTHi 2019 increased cytosolic Ca2+ levels, and the invasion of bronchial cells by NTHi 2019 was inhibited by pretreatment with the cell-permeant intracellular Ca2+ chelator BAPTA-AM (P = 0.022) or thapsigargin (P = 0.016). Cytosolic inositol phosphate (IP) levels were also increased after infection with NTHi 2019 (P < 0.001), but not after infection with isogenic mutants expressing altered LOS glycoforms lacking ChoP. PAF receptor antagonist reduced NTHi 2019-stimulated IP production in a dose-dependent manner. NTHi 2019 invasion was inhibited by pertussis toxin (PTX) and the phosphatidylinositol-3-kinase inhibitors wortmannin and LY294002. The less invasive strain NTHi 7502 also initiated IP production, but was unaffected by PAF receptor antagonist or PTX. These data demonstrate that the binding of the PAF receptor by NTHi initiates receptor coupling to a PTX-sensitive heterotrimeric G protein complex, resulting in a multifactorial host cell signal cascade and bacterial invasion. Moreover, the data suggest that NTHi strains initiate cell signalling and invade by different mechanisms, and that invasion mediated by PAF receptor activation is more efficient than macropinocytosis.
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PMID:Binding of the non-typeable Haemophilus influenzae lipooligosaccharide to the PAF receptor initiates host cell signalling. 1148 14

The ferric uptake regulation (fur) gene was cloned and characterized from Actinobacillus pleuropneumoniae and it exhibited 97% amino acid sequence identity to the Haemophilus ducrey fur gene. The flanking regions of the fur gene included an upstream putative flavodoxin (fldA) gene and a downstream possible transmembrane protein gene of unknown function. A single promoter was identified by 5' rapid amplification of cDNA ends (RACE), but there were no sequences homologous to an Escherichia coli Fur box in the 5' upstream sequence. The A. pleuropneumoniae fur clone complemented an E. coli fur deletion mutant. Transcriptional analysis of the divergent promoters of the A. pleuropneumoniae toxin I operon (apxICABD)--and the Actinobacillus ferric uptake operon (afuABC) showed that Fur and calcium together positively regulated the transcription of apxICABD while Fur was a repressor for afuABC. Hemolytic activity was significantly induced by iron and calcium and Fur appeared to act as an activator under high calcium conditions and as a repressor under low calcium conditions. A possible regulator-binding site was suggested by the properties of a point mutation in 33 bp upstream of the apxIC gene. This point mutation affected ApxI and Afu expression in response to iron, calcium, or Fur. These results provide further proof that calcium and the A. pleuropneumoniae Fur protein play a role in the expression of ApxI and Afu.
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PMID:Cloning and characterization of the Actinobacillus pleuropneumoniae fur gene and its role in regulation of ApxI and AfuABC expression. 1450 29

LBM415 (NVP PDF-713) is the first member of the peptide deformylase (PDF) inhibitor class being developed for clinical trials as a parenteral and oral agent for treatment of community-acquired respiratory tract disease and serious infections caused by antimicrobial-resistant gram-positive cocci. In this study susceptibility testing results from 1,306 recent clinical isolates selected to over-represent resistance trends among the species were summarized. All staphylococci (153 strains; MIC at which 90% of isolates were inhibited [MIC90], 2 microg/ml), Streptococcus pneumoniae (170 strains; MIC90, 1 microg/ml), other streptococci (150 strains; MIC90, 1 microg/ml), enterococci (104 strains; MIC90, 4 microg/ml), Moraxella catarrhalis (103 strains; MIC90, 0.5 microg/ml), and Legionella pneumophila (50 strains; MIC90, 0.12 microg/ml) were inhibited at < or = 8 microg of LBM415/ml, as were 97% of Haemophilus influenzae isolates (300 strains; MIC90, 4 to 8 microg/ml). Among other bacterial groups, 100% of gram-positive and -negative anaerobes, including 22 Bacteroides spp. strains (31 strains total; MIC90, 1 microg/ml), were inhibited by < or = 4 microg/ml, whereas Enterobacteriaceae (112 strains) and most nonfermentative bacilli (107 strains) were not inhibited at readily achievable concentrations. The compound was found to have a dominantly bacteriostatic action, and spontaneous single-step mutational rates occurred at low levels (10(-6) to <10(-8)). Drug interaction studies failed to identify any class-specific synergistic interactions, nor were antagonistic interactions observed. Variations in broth and agar MIC test conditions demonstrated that, whereas the agar-based method trended towards a 1-log2 dilution-higher MIC than the broth method and was inoculum dependent, other variations in incubation environment, medium supplements, pH, or calcium concentration had little influence on LBM415 MIC results. Use of the efflux inhibitor phe-arg-beta-naphthylamide showed an average of 1 log2 dilution decrease in H. influenzae MICs, demonstrating the contribution of efflux pumps in influencing susceptibility to PDF inhibitors. The in vitro activity of LBM415 against targeted bacterial species, including resistant subsets, and other laboratory characteristics of this novel compound demonstrate the potential of PDF inhibitors as a new class of antimicrobial agents.
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PMID:Comparative antimicrobial characterization of LBM415 (NVP PDF-713), a new peptide deformylase inhibitor of clinical importance. 1579 28


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