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

Cell envelopes of Haemophilus influenzae have been prepared by breakage in a French pressure cell followed by differential centrifugation. The envelope fraction may be resolved into an inner-membrane (light) and an outer-membrane (heavy) fraction on density gradients. Envelopes from competent cells possess elevated levels of lipopolysaccharide with a composition different from that of log-phase cell envelopes. Three apparently new polypeptides have been observed in envelopes from competent cells by gel electrophoresis in sodium dodecyl sulfate; additional quantitative alterations in the profiles of membrane polypeptides also company the development of the capacity to transport deoxyribonucleic acid. Most of the polypeptide changes are confined to the outer membrane; one new polypeptide is associated with the inner cytoplasmic membrane of competent cells. Protein synthesis during competence developement is rquired for the change in lipopolysaccharides and in the envelope polypeptides to occur.
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PMID:Constitution of the cell envelope of Haemophilus influenzae in relation to competence for genetic transformation. 108 Apr 85

Chancroid is a sexually transmitted diseased caused by Haemophilus ducreyi. The pathological manifestations of chancroid are unique among Haemophilus species and the virulence factors of H. ducreyi that account for these features have not been identified. Some of these virulence factors may be unique components of H. ducreyi, but attempts to identify H. ducreyi-specific components have been unsuccessful. Four polypeptides--A, B, C and D of 83, 77, 56 and 28 kDa, respectively--were identified with a panel of nine H. ducreyi-specific monoclonal antibodies (MAbs). Polypeptide C was one of the five major proteins in H. ducreyi and demonstrated micro-heterogeneity in SDS-PAGE. Polypeptides A, B and D were present in only small amounts in whole-cell lysates of H. ducreyi. The relative amounts of A and B varied, suggesting that they may be precursor molecules. The unique polypeptides C and D were not exposed on the surface. Polypeptide C was highly soluble and did not appear to be membrane-bound, whereas polypeptide D appeared to partition with the cytoplasmic membrane and was soluble in Sarkosyl. All four polypeptides appeared to be unique to H. ducreyi since MAbs directed against them did not cross-react with H. influenzae, H. parainfluenzae or Neisseria gonorrhoeae. The mol. wts of all of these polypeptides were conserved throughout 35 clinical isolates collected from 15 cities in eight countries and one reference strain of H. ducreyi that were tested.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Identification of highly conserved and species-specific polypeptides of Haemophilus ducreyi. 128 Dec 34

The ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae was cloned and sequenced. The structural gene encodes a 305 amino acid polypeptide. The ROB-1 beta-lactamase gene sequence is identical to that derived from Pasteurella haemolytica and only one amino acid different from that of Haemophilus influenzae, suggesting that they are derived from the same ancestor, and transformed from one to another.
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PMID:Sequence analysis of the ROB-1 beta-lactamase gene from Actinobacillus pleuropneumoniae. 145 27

Most Serratia marcescens strains produce a new type of cytolysin (hemolysin) which is also found in other Serratia species. The hemolytic polypeptide ShlA (M(r) 162 101) is secreted across the outer membrane through the help of the ShlB protein which also involves conversion of an inactive precursor in an hemolytically active form. Both proteins are synthesized with signal sequences which are released during export across the cytoplasmic membrane. Mutants expressing inactive ShlB derivatives are impaired in activation and secretion suggesting a tight coupling between both processes. The region of ShlA for activation and secretion is confined to the N-terminal 16% of the polypeptide which contains the sequence NPNG which is also found in the Proteus hemolysin, the Bordetella pertussis filamentous hemagglutinin and two highly expressed outer membrane proteins of Haemophilus influenzae. Substitution of the first asparagine (N) residue by isoleucine converts the Serratia hemolysin into an inactive secretion incompetent form. It is concluded that this region is recognized by ShlB for activation and secretion of ShlA. The Serratia hemolysin forms defined pores in erythrocyte membranes.
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PMID:Serratia marcescens forms a new type of cytolysin. 147 65

Haemophilus influenzae is a heme-dependent bacterium. However, little is known of the heme-iron uptake mechanism in this organism. By using a batch ligand affinity chromatography method, a hemin-binding protein of 39,500 molecular weight was isolated from total membranes derived from H. influenzae type b grown under iron-depleted but not under iron-sufficient conditions. Detection of the hemin-binding protein in a whole-cell binding assay demonstrated a surface-exposed location. Competition binding experiments indicated that this hemin-protein interaction was specific, since only hemin or heme-containing proteins, such as human hemoglobin and bovine catalase, but not protoporphyrin IX, iron-loaded human lactoferrin, or transferrin, could abrogate binding. In a limited survey of other H. influenzae strains, an identical hemin-binding protein was isolated, implying that this polypeptide may be structurally and functionally conserved among strains.
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PMID:Isolation of an outer membrane hemin-binding protein of Haemophilus influenzae type b. 154 54

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.
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PMID:Molecular cloning, nucleotide sequence, and characterization of a 40,000-molecular-weight lipoprotein of Haemophilus somnus. 154 56

The mechanism(s) used by Haemophilus influenzae to acquire the essential nutrient heme from its human host has not been elucidated. The heme carried by the high-affinity serum protein hemopexin is one potential source of this micronutrient in vivo. A colony-blot assay revealed that heme-human hemopexin-binding activity was shared among most capsular serotype b strains of H. influenzae but was uncommon among other strains. We have identified a recombinant clone binding heme-human hemopexin from a H. influenzae type b (Hib) genomic library expressed in Escherichia coli. Both the Hib strain and the heme-hemopexin-binding clone expressed a polypeptide of approximately 100 kDa that bound radiolabeled heme-hemopexin. Oligonucleotide linker insertion mutagenesis of the plasmid DNA from this recombinant clone was used to confirm that expression of the 100-kDa protein correlated with the heme-hemopexin-binding activity. Exchange of one of these mutant alleles into the Hib chromosome eliminated expression of both the 100-kDa protein and the heme-hemopexin-binding activity. Furthermore, this Hib mutant was unable to utilize heme-human hemopexin as a heme source.
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PMID:Identification of a genetic locus of Haemophilus influenzae type b necessary for the binding and utilization of heme bound to human hemopexin. 154 95

Thirty-four clinical isolates of noncapsulate Haemophilus influenzae representing isolates with either related or dissimilar patterns of whole-cell polypeptide profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were further characterized by restriction enzyme analysis (REA) and rRNA gene restriction patterns. Total cellular DNA was extracted by a rapid, microcentrifuge-scale method and digested with BamHI, which gave a pattern of about 18 discrete bands. This confirmed the five closely related groupings suggested by SDS-PAGE. Isolates dissimilar by SDS-PAGE were also distinguishable by REA. However, there was no correlation between the degrees of similarity estimated from whole-cell polypeptide profiles and those obtained from REA for the dissimilar isolates. Therefore, inferences of genetic relatedness made on the basis of these data should be interpreted with caution. rRNA gene restriction patterns also confirmed the groupings suggested by the other two techniques. We conclude that the three methods were highly discriminatory and that whole-cell polypeptide patterns or REA with BamHI would be appropriate techniques for epidemiological studies of noncapsulate H. influenzae.
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PMID:Characterization of noncapsulate Haemophilus influenzae by whole-cell polypeptide profiles, restriction endonuclease analysis, and rRNA gene restriction patterns. 170 27

Haemophilus somnus is a gram-negative bacterium capable of causing a number of disease syndromes in cattle. This article describes the cloning and characterization of a gene coding for a 15,000-molecular-weight (15K) polypeptide which reacts strongly with antiserum against H. somnus. Analysis of plasmid-encoded polypeptides by polyacrylamide gel electrophoresis showed that the corresponding gene is the second in a transcriptional unit. The first gene codes for a protein with a molecular weight of approximately 17,000. Using antiserum against the two recombinant proteins, we could show that the natural proteins are predominantly present in purified ribosomes from H. somnus. The nucleotide sequence of both genes and flanking regions has been determined, and the deduced amino acid sequence of the two polypeptides was used to search for sequence homology in the GenBank data base. The 15K polypeptide showed 89% similarity to the Escherichia coli ribosomal protein S9, and the 17K polypeptide showed 94% similarity to the E. coli ribosomal protein L13. In E. coli, the corresponding genes constitute a bicistronic operon, with the same gene order as that found in H. somnus. A plasmid expressing the 15K protein was found to complement an E. coli rpsI mutation. When a frameshift mutation was introduced into the 15K protein gene, the resulting plasmid failed to complement this rpsI mutation, demonstrating functional homology between the 15K protein and S9 from E. coli. Downstream from the 15K protein gene is located another open reading frame, which could code for a polypeptide with a predicted molecular weight of 24,427. A protein with a similar molecular weight was detected in minicells containing the recombinant clone. This polypeptide is 69% similar to the stringent starvation protein (Ssp) of E. coli.
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PMID:Cloning, sequencing, expression, and functional studies of a 15,000-molecular-weight Haemophilus somnus antigen similar to Escherichia coli ribosomal protein S9. 172 7

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.
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PMID:Characterization of a Legionella pneumophila gene encoding a lipoprotein antigen. 176 77


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