Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O75191 (H. influenzae)
 4,961 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The P2 porin protein is the most abundant outer membrane protein (OMP) of nontypeable Haemophilus influenzae (NTHI) and shows extensive antigenic heterogeneity among strains. To study the molecular basis of this heterogeneity, the DNA sequences of the genes encoding the P2 proteins of three unrelated strains of NTHI were determined, and restriction fragment length polymorphisms around the P2 genes of 35 strains were analyzed. The deduced amino acid sequences of the P2 genes from the three strains of NTHI revealed four major (12 to 35 amino acids long) and several smaller (2 to 7 amino acids) hypervariable regions in each protein. The major variations occurred in identical portions of the genes, and these regions showed a high antigenic index and surface exposure probability in computer modeling analysis. Differences in the molecular mass of the P2 protein correlate with differences in the size of the variable region in each strain. Oligonucleotide primers suitable for amplification of the P2 genes by polymerase chain reaction were developed. Restriction fragment length polymorphism analysis showed marked heterogeneity in and around the ompP2 locus of 35 NTHI strains. These results contrast with the high degree of conservation of the P2 genes in H. influenzae type b strains. We conclude that the molecular mass and antigenic heterogeneity of the P2 molecule of NTHI is due to variations in gene sequence that are clustered primarily in four large hypervariable regions of the gene.
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PMID:Molecular analysis of the P2 porin protein of nontypeable Haemophilus influenzae. 128 Jun 27

The P2 outer membrane protein of Haemophilus influenzae belongs to a class of apparently ubiquitous proteins in Gram-negative bacteria that function as porins. Murine hybridomas raised to the P2 protein and synthetic peptides were used to investigate the structural and antigenic relationships among P2 proteins of encapsulated and non-encapsulated H. influenzae. Three monoclonal antibodies (mAbs), P2-17, P2-18 and P2-19, recognizing epitopes on the P2 protein, as shown by Western immunoblotting of outer membrane preparations, and purified and recombinant P2 proteins are described. The epitopes reactive with the mAbs were widely distributed among H. influenzae strains since 70-100% of strains of encapsulated and non-encapsulated isolates collected worldwide were recognized by individual mAbs. None of the mAbs reacted with H. parainfluenzae or other bacterial species. The peptide composition of P2 epitopes was determined by analysis of mAb reactivity with a series of overlapping synthetic peptides that covered the amino acid sequences of H. influenzae type b. The domains recognized by these mAbs were completely distinct. mAb P2-18, reactive with an epitope conserved among all H. influenzae P2 porin molecules which were screened, recognized a peptide corresponding to the N-terminal segment (residues 1-14). The P2-17- and P2-19-specific epitopes were located between residues 28 and 55, and 101 and 129, respectively. None of the epitopes were exposed on the cell surface since no mAbs bound to intact live bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Localization of conserved B-cell epitopes among encapsulated and non-encapsulated Haemophilus influenzae P2 porin proteins using synthetic peptides. 137 28

Protein carriers vary in their ability to increase the immunogenicity of poorly immunogenic or T-lymphocyte-independent antigens. We examined one such carrier, the outer membrane protein complex derived from Neisseria meningitidis serogroup B strain B11, in an attempt to determine why this outer membrane protein complex was more immunogenic in young infants and in relevant animal models than two other carriers used in conjugates made with Haemophilus influenzae type b polysaccharide, a T-cell-independent antigen. A single protein of the outer membrane protein complex, the class 2 porin protein, was purified and shown to function as a T-helper lymphocyte carrier protein. Unexpectedly, it was also found to have mitogenic activity for lymphocytes that was not due to lipopolysaccharide. This mitogenic activity appears to date to be unique to this carrier protein of the carrier proteins tested and may contribute to the ability of the H. influenzae type b conjugate vaccine made with the outer membrane protein complex to generate IgG anti-polysaccharide antibody responses in mice and infant monkeys and protective immune responses in infants less than 6 months of age.
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PMID:A vaccine carrier derived from Neisseria meningitidis with mitogenic activity for lymphocytes. 153 34

The P2 porin protein is the major outer membrane protein of nontypeable Haemophilus influenzae. Five monoclonal antibodies to P2 of four strains of nontypeable H. influenzae were developed by immunizing mice with whole bacterial cells. All five antibodies recognized epitopes on P2 in immunoblot assays of whole organism lysates, purified outer membrane, and purified P2. Competitive enzyme-linked immunosorbent assays and immunoblot assays of cyanogen bromide-digested P2 showed that two antibodies to the P2 protein of strain 1479 recognized different epitopes on the molecule. Immunofluorescence and immunoelectron microscopy demonstrated that each of the five antibodies recognized epitopes that were abundantly expressed on the bacterial surface. Analysis of 120 H. influenzae strains indicated that three of the five antibodies were reactive exclusively with the homologous strain. The remaining two antibodies were reactive with less than 3% of the strains. These studies indicate that the P2 protein expresses a highly strain-specific and immunodominant epitope on the bacterial surface. The expression of strain-specific and immunodominant epitopes on the bacterial surface may represent a mechanism by which the bacterium induces antibodies that will protect against recurrent infection by the homologous strain but will not protect against infection by heterologous strains.
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PMID:Strain-specific and immunodominant surface epitopes of the P2 porin protein of nontypeable Haemophilus influenzae. 170 17

The P2 protein of Haemophilus influenzae type b has a porin activity and is the most abundant protein in the outer membrane. We have employed fusion protein constructs and synthetic peptides along with monoclonal antibodies to map B-cell epitopes in this protein. A linear, surface-exposed epitope was identified between residues 158 and 174. A second surface-exposed epitope was identified near the carboxy-terminal end of the protein (residues 319 to 341). Two additional B-cell epitopes were identified. One was localized between residues 28 and 55, whereas the other was located between residues 148 and 174. These epitopes were not present on the surface of intact H. influenzae cells. Thus, four distinct immunogenic and antigenic regions on the P2 protein have been identified.
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PMID:Mapping of B-cell epitopes on the outer membrane P2 porin protein of Haemophilus influenzae by using recombinant proteins and synthetic peptides. 170 22

Porins are pore-forming outer-membrane proteins which serve as a non-specific pathway for the entry of hydrophilic molecules into Gram-negative bacteria. We studied four strains of Haemophilus influenzae that had decreased permeability to chloramphenicol associated with diminished quantities of a 40 kDa major outer-membrane protein. Isogenic pairs of organisms containing and lacking this protein were compared. The latter strains grew more slowly and were less permeable to sucrose and raffinose. They were also more resistant to multiple hydrophilic antibiotics than an isogenic strain containing the 40 kDa protein and were less permeable to penicillin G and chloramphenicol. We conclude that the 40 kDa outer-membrane protein functions as a porin in H. influenzae.
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PMID:A major outer-membrane protein functions as a porin in Haemophilus influenzae. 244 11

The protein P2 comprises a large proportion of the outer membrane of nontypable Haemophilus influenzae and functions as a porin. In view of the importance of the protein as a surface antigen, the present study was designed to purify and analyze P2 with particular emphasis on detection of antigenic determinants expressed on the bacterial surface and identification of bactericidal targets on P2. The P2 protein was purified by using detergent solubility, anion-exchange chromatography, and gel-filtration chromatography sequentially. Two monoclonal antibodies to P2 were developed. One antibody (2E6) recognized a determinant expressed on the bacterial surface, whereas the other antibody (3F3) recognized an internal epitope. The surface-exposed 2E6 determinant was present on 12% of strains from a nationwide collection. P2 is a bactericidal target for antibody 2E6. Cyanogen bromide cleavage of P2 resulted in two fragments, as in type b strains. Both monoclonal antibodies recognized epitopes on the larger fragment. These observations have potentially important implications regarding the development of vaccines to prevent H. influenzae infections and the development of a serotyping system for epidemiologic studies.
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PMID:Purification and analysis with monoclonal antibodies of P2, the major outer membrane protein of nontypable Haemophilus influenzae. 245 40

The 40-kDa porin protein of Haemophilus influenzae type b was reconstituted into proteoliposomes. The relative rates of diffusion of small uncharged sugars across the channels formed by this protein were determined by measuring the rates of osmotic swelling of the liposomes. From these rates, a pore diameter of 1.8 nm was estimated using the Renkin equation. A chemical cross-linking technique was used to investigate the oligomeric structure of the 40-kDa porin. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis revealed the presence of porin dimers and trimers after reaction of the protein with dithio-bis-(succinimidyl propionate). These results confirmed that the porin of H. influenzae forms large water-filled channels and indicated that it probably exists as trimers in the outer membrane.
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PMID:Outer membrane porin protein of Haemophilus influenzae type b: pore size and subunit structure. 245 50

Outer membranes of Haemophilus influenzae type b were fractionated to yield Triton X-100-insoluble material and lipopolysaccharide and phospholipids. Liposomes reconstituted from lipopolysaccharide and phospholipids were impermeable to sucrose (Mr, 342) and to a high-molecular-weight dextran (average Mr, 6,600). When the Triton X-100-insoluble material was introduced into the reconstituted liposomes, the vesicles became permeable to sucrose, raffinose (Mr, 504), and stachyose (Mr, 666) and fully retained dextrans of Mr greater than 1,500. Inulin (average Mr, 1,400) was tested for its efflux from the reconstituted outer membrane vesicles; 62% of the added inulin was trapped. The molecular weight exclusion limit for the outer membrane of H. influenzae type b was therefore estimated at approximately 1,400. A protein responsible for the transmembrane diffusion of solutes was purified from H. influenzae type b by extraction of whole cells with cetyl trimethyl ammonium bromide. When this extract was passed over DEAE-Sepharose, three protein-containing peaks (I, II, and III) were eluted. Peaks I and II contained mixtures of proteins as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; when tested for their pore-forming properties, these proteins were unable to render liposomes of lipopolysaccharide and phospholipid permeable to sucrose. Peak III contained only one molecular species of protein of molecular weight 40,000; this protein acted as a porin in reconstituted vesicles. The molecular weight exclusion limit for 40,000-molecular-weight protein matched the estimate of approximately 1,400 which was determined for outer membranes. A series of homologous saccharides of increasing degree of polymerization was prepared from agarose by hydrolysis with beta-agarase and fractionation on gel filtration chromatography. These oligosaccharides of Mr, 936, 1,242, 1,548, and 1,854 were assayed for retention by the complete vesicles containing 40-kilodalton protein and lipopolysaccharide and phospholipids. All of these oligosaccharides were lost by efflux through the porin. Since the molecular conformation of the largest oligosaccharide is an elongated semirigid helix, it is suggested that the pore formed by the 40-kilodalton protein does not act as a barrier to the diffusion of this compound.
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PMID:Transmembrane permeability channels across the outer membrane of Haemophilus influenzae type b. 298 94

The major outer membrane protein (P2) of Haemophilus influenzae type b (Hib) with an apparent molecular weight of 37,000 to 40,000 has been previously shown to function as a porin and also as a target for antibodies protective against experimental Hib disease. The gene encoding the Hib P2 protein was cloned by using a shuttle vector capable of replication in both Escherichia coli and H. influenzae. The amino acid sequence of the amino terminus of the Hib P2 protein was determined and used to design an oligonucleotide probe corresponding to the first 20 amino acids of this protein. This oligonucleotide probe was used to identify Hib chromosomal DNA fragments containing the Hib P2 gene. These DNA fragments were ligated into the plasmid vector pGJB103 and then used to transform a rec-1 mutant of H. influenzae Rd. Recombinant clones expressing the Hib P2 protein were identified in a colony blot-radioimmunoassay by using a monoclonal antibody specific for a surface epitope of the Hib P2 protein. The gene encoding this Hib protein was present on a 10-kilobase Hib DNA insert in the recombinant plasmid. Transformation experiments involving the recombinant plasmid suggested that unregulated synthesis of Hib P2 is a lethal event in E. coli. The recombinant Hib P2 protein was exposed on the surface of the recombinant H. influenzae strain. This recombinant strain was used to develop a system for detecting polyclonal serum antibodies directed against surface determinants of the Hib P2 protein. The availability of the gene encoding the Hib P2 protein should facilitate investigation of both the immunogenicity and the structure-function relationship(s) of this major outer membrane protein.
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PMID:Cloning of the gene encoding the major outer membrane protein of Haemophilus influenzae type b. 326 90


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