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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoclonal antibodies to polyribosylribitolphosphate (PRP), the capsular polysaccharide of Haemophilus influenzae type b (Hib), are useful tools in the investigation of the molecular and cellular mechanisms causing Hib meningitis. A better understanding of these mechanisms may lead to improved therapeutic strategies. A number of different in vivo immunization techniques in BALB/c mice were used, which did not however reveal detectable serum levels of antibodies to PRP. Therefore a modified in vitro immunization technique, originally established for in vitro immunization of human B lymphocytes, was used for this weak immunogen in mice. After 5 days of in vitro stimulation with purified PRP the splenic lymphocytes of BALB/c mice were fused with the mouse myeloma line P3-X63-Ag8.653. One hybridoma produced an IgM antibody (12E7) which recognized the capsular polysaccharide in ELISA and specifically labelled all tested Hib strains in immune fluorescent microscopy. The blotted polysaccharide PRP was immunostained with monoclonal antibody 12E7. Preincubation of Hib with this antibody enhanced the oxygen radical metabolism of polymorphnuclear leucocytes in a chemiluminescence assay. There was no cross-reactivity with the supernatants of other Haemophilus influenzae serotypes and other bacterial species, as shown by counterimmunoelectrophoresis.
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PMID:Characterization of a monoclonal antibody to the capsule of Haemophilus influenzae type b, generated by in vitro immunization. 782 41

Extracellular transport of Neisseria IgA proteases across the bacterial outer membrane is accomplished by the translocation function contained within the C-terminal Iga beta domain of IgA protease precursor proteins. Recently, we reported that Iga beta from N. gonorrhoeae MS11 (Val1097 to Phe1505), fused to a periplasmic passenger protein, facilitated its transport across the outer membrane, leading to surface exposure of the passenger. In the present work we show, by systematic N-terminal truncation of Iga beta, that the functional and structural unit, termed Iga beta-core, corresponds to the C-terminal approximately 274 amino acid residues (Ser1231 to Phe1505). This minimal region retains all the essential features necessary for the translocation of an N-terminally attached passenger across the outer membrane of Escherichia coli, and for its own correct integration into the outer membrane, even in the absence of a passenger protein. The membrane-integrated Iga beta-core constitutes a conserved entity found in the C-terminal regions of Iga beta domains of different N. gonorrhoeae, N. meningitidis and Haemophilus influenzae strains. In contrast, the surface-exposed N termini of the Iga beta domains vary in size and sequence. Based on secondary structure predictions, the key structural feature of the core is a beta-barrel (amphipathic, antiparallel transmembrane beta-strands, interspersed by hairpin turns and loops) which is common to many integral outer membrane proteins of Gram-negative bacteria. We propose that the core has been conserved in evolution, to provide a selective outer membrane export channel for covalently attached polypeptides.
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PMID:Characterization of the Neisseria Iga beta-core. The essential unit for outer membrane targeting and extracellular protein secretion. 825 61

The completely sequenced genome of Haemophilus influenzae has been analysed for proteins of the phosphoenolpyruvate: sugar phosphotransferase system (PTS). We show that within the fructose PTS H. influenzae possesses a novel multi-domain phosphoryl transfer protein, not previously recognized, that includes two fructose-specific HPr domains fused in tandem in a single polypeptide chain.
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PMID:Novel PTS proteins revealed by bacterial genome sequencing: a unique fructose-specific phosphoryl transfer protein with two HPr-like domains in Haemophilus influenzae. 876 8

We have developed a new method for isolating translation initiation sites based on the expression of Haemophilus influenzae Rd gene fusions with the Escherichia coli galactokinase (galK) gene. We cloned random DNA fragments of H. influenzae Rd DNA into a plasmid vector containing the galK coding sequence from which the translation initiation site (the ribosome binding site and translation initiation codon) had been removed. A subset of the cloned DNA fragments contained translation initiation sites that, when fused to the galK gene, produced active galactokinase and complemented the host galK mutation. Molecules expressing galactokinase activity were isolated and characterized by DNA sequence analysis, and the sequences were aligned with the recently completed whole genomic sequence of H. influenzae Rd. Translation initiation sites for known, hypothetical, and new genes were identified. Translation initiation sites internal to the coding sequences of a number of genes were identified, suggesting that internal translation initiation sites are common, especially in large genes. This shotgun method provides functional information on translation initiation sites and helps to define gene coding sequences.
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PMID:A whole genome shotgun gene fusion method for isolation of translation initiation sites in Escherichia coli: identification of Haemophilus influenzae translation initiation sites in E. coli. 968 20

The dcuD gene (formerly yhcL) of Escherichia coli shows significant sequence similarity only to the dcuC gene of E. coli, which encodes a C4-dicarboxylate carrier (DcuC) that functions during anaerobic growth. Inactivation of dcuD had no effect on the growth of E. coli under a large number of conditions and led to no detectable changes in phenotype. Translational dcuD'-'lacZ gene fusions were not significantly expressed in the presence of dicarboxylates or monocarboxylates under oxic or anoxic conditions. Other potential substrates such as amino sugar derivatives, amino acids, and alpha-aspartyl dipeptides also did not lead to expression of dcuD. Changes in medium composition, pH, ionic strength, and temperature had no significant effects on dcuD expression. A dcuD gene amplified from a natural isolate of E. coli was not expressed in wild-type and E. coli K-12 backgrounds. Cloning of dcuD behind an inducible promoter resulted in the synthesis of a protein of the expected size (49 kDa), which, however, did not complement for the loss of DcuC or other C4-dicarboxylate carriers. It is suggested that dcuD encodes a protein of the DcuC family of anaerobic C4-dicarboxylate carriers and that dcuD is not significantly expressed or is expressed only under conditions not related to carboxylate metabolism. When two adjacent open reading frames (y0585 and y0586) from Haemophilus influenzae are fused, the resulting hypothetical protein has sequence similarity to DcuC and DcuD.
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PMID:The dcuD (former yhcL) gene product of escherichia coli as a member of the DcuC family of C4-dicarboxylate carriers: lack of evident expression 1052 38

A large-scale effort to measure, detect and analyse protein-protein interactions using experimental methods is under way. These include biochemistry such as co-immunoprecipitation or crosslinking, molecular biology such as the two-hybrid system or phage display, and genetics such as unlinked noncomplementing mutant detection. Using the two-hybrid system, an international effort to analyse the complete yeast genome is in progress. Evidently, all these approaches are tedious, labour intensive and inaccurate. From a computational perspective, the question is how can we predict that two proteins interact from structure or sequence alone. Here we present a method that identifies gene-fusion events in complete genomes, solely based on sequence comparison. Because there must be selective pressure for certain genes to be fused over the course of evolution, we are able to predict functional associations of proteins. We show that 215 genes or proteins in the complete genomes of Escherichia coli, Haemophilus influenzae and Methanococcus jannaschii are involved in 64 unique fusion events. The approach is general, and can be applied even to genes of unknown function.
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PMID:Protein interaction maps for complete genomes based on gene fusion events. 1057 11

Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen associated with otitis media and the exacerbation of chronic bronchitis. This study reports the vaccine potential of three peptides representing conserved regions of the NTHi P5 outer membrane protein which have been fused to a promiscuous measles virus F protein T-cell eptitope (MVF). The peptides correspond to a region in surface loop one (MVF/L1A), the central region of loop four (MVF/L4), and a C-terminal region homologous to peptide 10 of OprF from Pseudomonas aeruginosa (MVF/H3). Immunization of rats with MVF/H3 was the most efficacious in significantly reducing the number of viable NTHi in both the broncho-alveolar lavage fluid (74%) and lung homogenates (70%), compared to control rats. Importantly, despite significantly increased rates of clearance, immunization with MVF/H3 elicited poor antibody responses, suggesting that cell-mediated rather than humoral responses play an important role in the enhanced clearance of NTHi in this model.
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PMID:A P5 peptide that is homologous to peptide 10 of OprF from Pseudomonas aeruginosa enhances clearance of nontypeable Haemophilus influenzae from acutely infected rat lung in the absence of detectable peptide-specific antibody. 1060 11

Haemophilus influenzae is an obligate commensal of the upper respiratory tract of humans that uses simple repeats (microsatellites) to alter gene expression. The mod gene of H. influenzae strain Rd has homology to DNA methyltransferases of type III restriction/modification systems and has 40 tetranucleotide (5'-AGTC) repeats within its open reading frame. This gene was found in 21 out of 23 genetically distinct H. influenzae strains, and in 13 of these strains the locus contained repeats. H. influenzae strains were constructed in which a lacZ reporter was fused to a chromosomal copy of mod downstream of the repeats. Phase variation occurred at a high frequency in strains with the wild-type number of repeats. Mutation rates were derived for similarly engineered strains, containing different numbers of repeats. Rates increased linearly with tract length over the range 17-38 repeat units. The majority of tract alterations were insertions or deletions of one repeat unit with a 2:1 bias towards contractions of the tract. These results demonstrate the number of repeats to be an important determinant of phase variation rate in H. influenzae for a gene containing a microsatellite.
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PMID:The length of a tetranucleotide repeat tract in Haemophilus influenzae determines the phase variation rate of a gene with homology to type III DNA methyltransferases. 1063 91

The outer membrane protein of Oma87 from Pasteurella multocida A:1 has significant similarity to the D15 protective antigen of Haemophilus influenzae (Ruffolo and Adler, 1996). Four fragments of Oma87 from a P. multocida serotype D strain were cloned into a pGEX expression vector and transformed into E. coli JM105. Western blot analysis revealed that convalescent chicken sera reacted with only GST-F1 fusion protein which contained amino acids 18 through to 130 of Oma87 fused to the GST protein. Vaccination with the GST-F1 protein failed to protect chickens against challenge with a virulent P. multocida serotype A.
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PMID:Overexpression and immunogenicity of the Oma87 outer membrane protein of Pasteurella multocida. 1069 6

Protein homology is often limited to long structural segments that we have previously called modules. We describe here a suite of programs used to catalog the whole set of modules present in microbial proteomes. First, the Darwin AllAll program detects homologous segments using thresholds for evolutionary distance and alignment length, and another program classifies these modules. After assembling these homologous modules in families, we further group families which are related by a chain of neighboring unrelated homologous modules. With the automatic analysis of these groups of families sharing homologous modules in independent multimodular proteins, one can split into their component parts many fused modules and/or deduce by logic more distant modules. All detected and inferred modules are reassembled in refined families. These two last steps are made by a unique program. Eventually, the soundness of the data obtained by this experimental approach is checked using independent tests. To illustrate this modular approach, we compared four proteobacterial proteomes (Campylobacter jejuni, Escherichia coli, Haemophilus influenzae, and Helicobacter pylori). It appears that this method might retrieve from present-day proteins many of the modules which can help to trace back ancient events of gene duplication and/or fusion.
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PMID:A strategy to retrieve the whole set of protein modules in microbial proteomes. 1246 1


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