Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A membrane-associated lipoprotein of Haemophilus influenzae type b has previously been shown to bind heme in vitro and to promote binding of this compound by Escherichia coli recombinants expressing this protein. The H. influenzae type b heme-binding protein A (HbpA) was found to be highly conserved with respect to both antigenicity and apparent molecular weight among heme-requiring Haemophilus species pathogenic for humans. To further the characterization of the structure and function of HbpA, the complete nucleotide sequence of its gene, hbpA, was determined. Analysis of the nucleotide sequence revealed a single large open reading frame of 1,638 bp encoding a protein of 546 amino acid residues, with a molecular weight of 60,695. The sequence of the amino-terminal end of this protein contained a potential site for lipid acylation and for cleavage by signal peptidase II, consistent with earlier biochemical evidence which indicated that HbpA is a lipoprotein. A search of GenBank for proteins with amino acid sequence similarity to HbpA revealed that the periplasmic dipeptide transport protein of E. coli, DppA, has 53% sequence identity to HbpA.
 ...
PMID:The hbpA gene of Haemophilus influenzae type b encodes a heme-binding lipoprotein conserved among heme-dependent Haemophilus species. 133 9

A gene of Haemophilus somnus encoding the major 40,000-molecular-weight antigen (LppA) was cloned on a 2-kb Sau3AI fragment. The nucleotide sequence of the entire DNA insert was determined. One open reading frame, encoding a 247-residue polypeptide with a calculated molecular weight of 27,072, was identified. This reading frame was confirmed by sequencing the fusion joint of two independent IppA::TnphoA gene fusions. The 21 amino-terminal amino acids of the deduced polypeptide showed strong sequence homology to the signal peptide of secreted proteins, and the sequence Leu-Leu-Ala-Ala-Cys at the putative cleavage site is identical to the consensus cleavage sequence of lipoproteins from gram-negative bacteria. The presence of the lipid moiety on the protein was shown by incorporation of radioactive palmitic acid into the natural H. somnus protein. Palmitic acid could also be incorporated into the recombinant protein in Escherichia coli. Synthesis of the mature LppA lipoprotein was inhibited by globomycin, showing that cleavage of the signal peptide is mediated by signal peptidase II in both organisms. By using site-directed mutagenesis, the cysteine residue at the cleavage site was changed to glycine. Radiolabelled palmitate was not incorporated into the mutated protein, showing that lipid modification occurs at the Cys-22 residue.
 ...
PMID:Molecular cloning, nucleotide sequence, and characterization of a 40,000-molecular-weight lipoprotein of Haemophilus somnus. 154 56

A prominent 19 kDa surface antigen of Legionella pneumophila, cloned in Escherichia coli, was found to be intimately associated with peptidoglycan. The DNA region encoding this antigen was mapped on an 11.9 kb plasmid by means of deletion analysis and transposon mutagenesis. PhoA+ gene fusions, gene-rated by TnphoA insertions into this region, confirmed the presence of a gene encoding a secreted protein. PhoA+ transposon insertions were also associated with loss of the 19 kDa antigen in immunoassays using a monoclonal antibody (mAb1E9) and the replacement of the 19 kDa antigen with larger fusion proteins in immunoblots using Legionella immune serum. A 1540bp PstI fragment carrying the gene was sequenced, and the open reading frame encoding the antigen was identified. The gene encodes a polypeptide 176 amino acid residues long and 18913Da in size. The presence of a signal sequence of 22 amino acids with a consensus sequence for cleavage by signal peptidase II indicates that the antigen is a lipoprotein, and striking similarity with peptidoglycan-associated lipoproteins (PALs) from E. coli (51% amino acid homology) and Haemophilus influenzae (55% homology) is noted. We conclude that the 19kDa antigen of L. pneumophila is the structural equivalent of the PAL found in other Gram-negative species and suggest that its post-translational acylation may explain its potency as an immunogen.
 ...
PMID:Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen. 176 77

Haemophilus influenzae, a strict human pathogen, acquires iron in vivo through the direct binding and removal of iron from human transferrin by an as yet uncharacterized process at the bacterial cell surface. In this study, the tbpA and tbpB genes of H. influenzae, encoding the transferrin-binding proteins Tbp1 and Tbp2, respectively, were cloned and sequenced. Alignments of the H. influenzae Tbp1 and Tbp2 protein sequences with those of related proteins from heterologous species were analyzed. On the basis of similarities between these and previously characterized proteins, Tbp1 appears to be a member of the TonB-dependent family of outer membrane proteins while Tbp2 is lipid modified by signal peptidase II. Isogenic mutants deficient in expression of Tbp1 or Tbp2 or both proteins were prepared by insertion of the Tn903 kanamycin resistance cassette into cloned sequences and reintroduction of the interrupted sequences into the wild-type chromosome. Binding assays with the mutants showed that a significant reduction in transferrin-binding ability resulted from the loss of either of the Tbps and a complete loss of binding was evident when neither protein was expressed. Loss of either Tbp2 or both proteins correlated with an inability to grow on media supplemented with transferrin-bound iron as the sole source of iron, whereas the Tbp1+ Tbp2- mutant was able to grow only at high transferrin concentrations.
 ...
PMID:Identification and characterization of genes encoding the human transferrin-binding proteins from Haemophilus influenzae. 789 Mar 73

Haemophilus somnus is a facultative intracellular pathogen which causes a wide range of diseases in cattle. To identify putative virulence determinants, a genomic library of H. somnus in Escherichia coli was screened for Congo red binding, a property associated with virulence in pathogenic bacteria, and subsequently with bovine hyperimmune sera raised against H. somnus HS25. A Congo red-binding clone carrying a 1.8-kb DNA insert was found to encode a strongly seroreactive LppB protein with an apparent molecular weight of 40,000. The nucleotide sequence of the entire DNA insert was determined. Two open reading frames coding for polypeptides with calculated molecular weights of 21,893 and 30,721 were identified. The larger open reading frame encoded LppB, while the smaller reading frame encoded a nonseroreactive protein with a relative molecular mass of approximately 18 kDa. The 16 amino-terminal amino acids of the deduced LppB polypeptide showed strong sequence homology to the signal peptide of secreted bacterial proteins, and the sequence Leu-Ala-Ala-Cys at the putative cleavage site corresponds to the consensus cleavage sequence of bacterial lipoproteins. Synthesis of the mature LppB lipoprotein in H. somnus was inhibited by globomycin, a specific inhibitor of signal peptidase II. LppB was localized to the outer membrane of H. somnus.
 ...
PMID:Molecular cloning, nucleotide sequence, and characterization of lppB, encoding an antigenic 40-kilodalton lipoprotein of Haemophilus somnus. 847 68

We cloned and expressed in Escherichia coli a gene encoding an 18-kDa outer membrane protein (Omp18) from Campylobacter jejuni ATCC 29428. The nucleotide sequence of the gene encoding Omp18 was determined, and an open reading frame of 165 amino acids was revealed. The amino acid sequence had the typical features of a leader sequence and a signal peptidase II cleavage site at the N-terminal part of Omp18. Moreover, the sequence had a high degree of similarity to the peptidoglycan-associated outer membrane lipoprotein P6 of Haemophilus influenzae and the peptidoglycan-associated lipoprotein PAL of E. coli. Southern blot analysis in which the cloned gene was used as a probe revealed genes similar to that encoding Omp18 in all species of the thermophilic group of campylobacters as well as Campylobacter sputorum. All campylobacters tested expressed a protein with a molecular mass identical to that of Omp18. The protein reacted immunologically with polyclonal antibodies directed against Omp18 from C. jejuni. PCR amplification of the gene encoding Omp18 with specific primers and subsequent restriction enzyme analysis of the amplified DNA fragments showed that the gene for Omp18 is highly conserved in C. jejuni strains isolated from humans, dogs, cats, calves, and chickens but is different in other Campylobacter species. In order to obtain pure recombinant Omp18 protein for serological assays, the cloned gene for Omp18 was genetically modified by replacing the signal sequence with a DNA segment encoding six adjacent histidine residues. Expression of this construct in E. coli allowed purification of the modified protein (Omp18-6xHis) by metal chelation chromatography. Sera from patients with past C. jejuni infection reacted positively with Omp18-6xHis, while sera from healthy blood donors showed no reaction with this antigen. Omp18, which is an outer membrane protein belonging to the family of PALs is well conserved in C. jejuni and is highly immunogenic. It is therefore a good candidate as an antigen for the serological diagnosis of past C. jejuni infections.
 ...
PMID:Identification and characterization of an immunogenic outer membrane protein of Campylobacter jejuni. 857 27

We report the purification, molecular cloning, and characterization of a 40-kDa glycerophosphodiester phosphodiesterase homolog from Borrelia hermsii. The 40-kDa protein was solubilized from whole organisms with 0.1% Triton X-100, phase partitioned into the Triton X-114 detergent phase, and purified by fast-performance liquid chromatography (FPLC). The gene encoding the 40-kDa protein was cloned from a B. hermsii chromosomal DNA lambda EXlox expression library and identified by using affinity antibodies generated against the purified native protein. The deduced amino acid sequence included a 20-amino-acid signal peptide encoding a putative leader peptidase II cleavage site, indicating that the 40-kDa protein was a lipoprotein. Based on significant homology (31 to 52% identity) of the 40-kDa protein to glycerophosphodiester phosphodiesterases of Escherichia coli (GlpQ), Bacillus subtilis (GlpQ), and Haemophilus influenzae (Hpd; protein D), we have designated this B. hermsii 40-kDa lipoprotein a glycerophosphodiester phosphodiesterase (Gpd) homolog, the first B. hermsii lipoprotein to have a putative functional assignment. A nonlipidated form of the Gpd homolog was overproduced as a fusion protein in E. coli BL21(DE3)(pLysE) and was used to immunize rabbits to generate specific antiserum. Immunoblot analysis with anti-Gpd serum recognized recombinant H. influenzae protein D, and conversely, antiserum to H. influenzae protein D recognized recombinant B. hermsii Gpd (rGpd), indicating antigenic conservation between these proteins. Antiserum to rGpd also identified native Gpd as a constituent of purified outer membrane vesicles prepared from B. hermsii. Screening of other pathogenic spirochetes with anti-rGpd serum revealed the presence of antigenically related proteins in Borrelia burgdorferi, Treponema pallidum, and Leptospira kirschneri. Further sequence analysis both upstream and downstream of the Gpd homolog showed additional homologs of glycerol metabolism, including a glycerol-3-phosphate transporter (GlpT), a glycerol-3-phosphate dehydrogenase (GlpD), and a thioredoxin reductase (TrxB).
 ...
PMID:Sequence analysis and characterization of a 40-kilodalton Borrelia hermsii glycerophosphodiester phosphodiesterase homolog. 907 9

We report the cloning, sequencing, and analysis of a novel chromosomal gene of Streptococcus equisimilis strain H46A that codes for a membrane lipoprotein, designated LppC. The lppC gene is located 3' adjacent to, and co-oriented with, the unrelated gapC gene that encodes the previously characterized glyceraldehyde-3-phosphate dehydrogenase. Sequencing of lppC revealed an 855-bp open reading frame that predicted a 32.4-kDa polypeptide possessing a potential lipoprotein signal sequence and modification site (VTGC). Signal sequence processing of LppC synthesized in the homologous host or expressed from plasmid pLPP2 in Escherichia coli was sensitive to globomycin, a selective inhibitor of lipoprotein-specific signal peptidase II. Subcellular localization of LppC using polyclonal antibodies raised to the hexahistidyl-tagged protein proved LppC to be tightly associated with the cytoplasmic membrane of S. equisimilis and with the outer membrane of E. coli JM109 (pLPP2). Southern, Northern and Western analyses indicated that lpp was conserved in S. pyogenes, and transcribed independently of gap as monocistronic 0.9-kb mRNA from a sigma 70-like consensus promoter. Database searches found homology of LppC to the hel gene-encoded outer membrane protein e (P4) from Haemophilus influenzae to which it exhibits 58% sequence similarity. However, unlike the hel gene, lppC was unable to complement hemA mutants of E. coli for growth on hemin as sole porphyrin source in aerobic conditions. Furthermore, neither the wild type nor an lppC insertion mutant of S. equisimilis could grow on hemin in iron-limited medium. These results, together with findings indicating that S. equisimilis H46A had no absolute requirement for iron, led us to conclude that lppC, in contrast to hel, is not involved in hemin utilization and has yet to be assigned a function.
 ...
PMID:The lppC gene of Streptococcus equisimilis encodes a lipoprotein that is homologous to the e (P4) outer membrane protein from Haemophilus influenzae. 925 68

A novel outer membrane lipoprotein in Pseudomonas aeruginosa is encoded by the omlA gene, which was identified immediately upstream of the fur (ferric uptake regulator) gene. The omlA and fur genes were divergently transcribed and had overlapping promoter regions. The proximal fur P2 promoter and the omlA promoter shared a 5-bp DNA motif for their -10 promoter elements. The distal fur P1 promoter was located within the omlA coding sequence, and the omlA and fur T1 mRNAs overlapped by 154 nucleotides. Optimal expression of both fur and omlA required roughly 200 bp of DNA upstream of the promoter regions, suggesting the presence of cis-acting transcriptional activation elements located within the omlA and fur genes, respectively. The levels of Fur and OmlA proteins had no influence on omlA or fur expression, excluding any trans-acting cross-regulation between fur and omlA. Expression of omlA was constitutive regardless of growth phase, oxygen tension, iron concentration, pH, and temperature. OmlA contained a signal sequence typical of bacterial lipoproteins, with a cysteine as a putative cleavage and lipid attachment site. Inhibition of signal peptidase II by globomycin resulted in failure to process OmlA, thus giving strong evidence that OmlA is a lipoprotein. Cell fractionation followed by Western blot analysis indicated that all OmlA protein is localized in the outer membrane. Mature OmlA was an acidic (pI = 4. 5) protein of 17.3 kDa and had close to 40% amino acid sequence identity to SmpA (small protein A) of Escherichia coli, Vibrio cholerae, and Haemophilus influenzae, a protein of unknown function. All P. aeruginosa strains tested as well as Pseudomonas fluorescens were found to produce OmlA. A mutant strain with impaired production of OmlA but no change in the expression of the overlapping fur gene was constructed. The omlA mutant was hypersusceptible to anionic detergents such as sodium dodecyl sulfate and deoxycholate, and it showed increased susceptibility to various antibiotics, including nalidixic acid, rifampin, novobiocin, and chloramphenicol. A structural role of OmlA in maintaining the cell envelope integrity is proposed.
 ...
PMID:Pseudomonas aeruginosa fur overlaps with a gene encoding a novel outer membrane lipoprotein, OmlA. 997 34

The identification of Brachyspira hyodysenteriae outer membrane proteins (OMPs) that may stimulate immunity to swine dysentery is important for vaccine development. We report here the analysis of a novel locus, blpGFEA, encoding four tandem paralogous proteins of approximately 30 kDa from B. hyodysenteriae. The four proteins share 31-39% sequence identity with lipoproteins from several species of bacterial pathogens, but the locus possesses a unique genetic organization. Using antisera raised to recombinant versions of each of these proteins, only BlpA and BlpE were found to be immunologically cross-reactive with the other proteins encoded by the locus. Northern hybridization indicated that only blpA was expressed under in vitro growth conditions. In addition, convalescent swine serum recognized recombinant BlpA in immunoblotting experiments, demonstrating that it is also expressed during infection. Analysis of the translated sequences of each of the genes revealed atypical spirochetal signal peptidase II recognition sites, and BlpA was shown to be a lipoprotein by incorporation of tritiated palmitic acid. Native BlpA was completely extracted by Triton X-114 (TX-114) and partitioned exclusively into the detergent phase during extraction of whole B. hyodysenteriae cells, implicating it as a component of the brachyspiral outer membrane. Consistent with the transcriptional and immunological data, analysis of the brachyspiral outer membrane proteome also revealed expression of only BlpA. Notably, inactivation of blpA homologs in Haemophilus influenzae and Salmonella enteritidis resulted in attenuation of virulence.
 ...
PMID:Characterization of a locus encoding four paralogous outer membrane lipoproteins of Brachyspira hyodysenteriae. 1270 40


1