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)

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

An isogenic mutant of Haemophilus influenzae type b (Hib) lacking the ability to express the P2 major outer membrane (porin) protein was constructed and characterized in various model systems. Linker insertion mutagenesis of a cloned Hib DNA insert containing the P2 structural gene was used in conjunction with a genetic transformation system to obtain a transformant unreactive with a P2-specific monoclonal antibody. This transformant was shown to lack detectable P2 protein by both protein staining and immunoblot methods. The P2 mutant exhibited a generation time in complex broth medium that was significantly longer than that of the wild-type parent strain. The P2 mutant was also unable to produce detectable bacteremia in infant rats after intraperitoneal challenge, while the wild-type parent strain produced bacteremia in all animals challenged with this strain. Reintroduction of a wild-type copy of the P2 gene into this mutant yielded a transformant strain that had a generation time in vitro identical to that of the wild-type parent strain and that was also fully virulent in the infant rat model. These findings suggest that the ability to synthesize the P2 protein may be necessary but not sufficient for full expression of virulence by this pathogen.
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PMID:Characterization of a mutant of Haemophilus influenzae type b lacking the P2 major outer membrane protein. 216 63

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

The P2 porin protein is the most abundant protein in the outer membrane of Haemophilus influenzae type b (Hib). Biochemical and immunochemical techniques were used to characterize the P2 proteins from a number of different Hib strains. P2 proteins from Hib outer membrane vesicles were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to nitrocellulose for in situ tryptic digestion. Solid-phase tryptic digests of P2 from eight Hib strains were resolved by high-pressure liquid chromatography and shown to be similar if not identical. Radioimmunoprecipitation analysis involving Hib cells (containing intrinsically radiolabeled proteins or lipooligosaccharide) and Western blot (immunoblot) analysis were used to identify two P2-specific murine monoclonal antibodies (MAbs). These MAbs were shown to be reactive with 120 Hib strains tested in a colony blot radioimmunoassay. One of these MAbs bound to a surface-exposed P2 epitope that was antibody accessible on all Hib strains tested; the other MAb was directed against a P2 epitope that either was not exposed on the cell surface or was otherwise inaccessible to antibody.
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PMID:Structural and antigenic conservation of the P2 porin protein among strains of Haemophilus influenzae type b. 247 70

The structural gene for the porin of Haemophilus influenzae type b, designated outer membrane protein P2, was cloned, and the DNA sequence was determined. An oligonucleotide probe generated by reverse translation of N-terminal amino acid sequence data from the purified protein was used to screen genomic DNA. The probe detected a single EcoRI fragment of approximately 1,700 base pairs which was cloned to lambda gt11 and then into M13 and partially sequenced. The derived amino acid sequence indicated that we had cloned the N-terminal portion of the P2 gene. An overlapping approximately 1,600-base-pair PvuII genomic fragment was cloned into M13, and the sequence of the remainder of the P2 gene was determined. The gene for P2 was then reconstructed under the control of the T7 promoter and expressed in Escherichia coli. The N-terminal sequence of the purified protein corresponds to residues 21 through 34 of the derived amino acid sequence. Thus, the protein is synthesized with a 20-amino-acid leader peptide. The Mr of the processed protein is 37,782, in good agreement with the estimate of 37,000 from sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
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PMID:Molecular cloning, expression, and primary sequence of outer membrane protein P2 of Haemophilus influenzae type b. 253 36

Sequencing techniques for single- and double-stranded DNA were used to determine the nucleotide sequence of the gene encoding P2, the major outer membrane (porin) protein of Haemophilus influenzae type b (Hib). The open reading frame encoding the P2 protein comprised 361 amino acid codons. Comparison of the inferred amino acid sequence with data obtained by amino acid sequencing of the N terminus of the mature or fully processed P2 protein revealed that this protein has a signal peptide composed of 20 amino acids. N-terminal amino acid sequencing of tryptic peptides derived from purified P2 allowed direct identification of 158 of the 341 amino acids in the fully processed P2 protein; there was 100% correlation between these amino acid sequences and that inferred from the nucleotide sequence. The amino acid sequence of Hib P2 protein had 23 to 25% homology with the sequence of the OmpF porin of Escherichia coli and with that of the Neisseria gonorrhoeae porin P.IA. Codon usage in the Hib P2 gene was significantly different from that observed for a gene encoding a porin of E. coli. DNA hybridization studies indicated that there is a single copy of the P2 gene in the Hib chromosome. The availability of the nucleotide and amino acid sequences for the Hib P2 protein will facilitate investigation of the antigenic characteristics and structure-function relationship of this porin.
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PMID:Primary structure of the porin protein of Haemophilus influenzae type b determined by nucleotide sequence analysis. 253 96

In previous studies, it has been demonstrated that outer membrane protein P2 from Haemophilus influenzae type b has porin activity and that antibody directed against P2 is protective in an infant rat bacteraemic model. Outer membrane protein subtyping has been employed to subclassify type b Haemophilus isolates. Strain MinnA has the outer membrane protein subtype 1H and is representative of the dominant clonal group of disease-producing isolates in the United States. In the present study, the P2 gene from strain MinnA was employed to probe EcoRI- and Pvull-digested chromosomal DNA from 24 Haemophilus influenzae type b isolates representative of the common outer membrane protein subtype groups observed throughout the world. Restriction fragment length polymorphisms were identified for the members of the outer membrane protein subtype 3L group, but not for the other subtypes examined. The P2 gene from each of four prototype isolates was then cloned, sequenced and compared to the previously reported sequence of the strain MinnA gene. The P2 gene from each of two isolates with the outer membrane protein subtype 3L was identical to the MinnA P2 sequence. The P2 gene from a subtype 2L isolate differed by a single nucleotide and the gene from a subtype 6U isolate differed by 13 nucleotides. Thus, the P2 protein is highly conserved among type b isolates.
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PMID:Diversity of the outer membrane protein P2 gene from major clones of Haemophilus influenzae type b. 257 96


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