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)

We have purified to homogeneity a peptidoglycan-associated protein from Haemophilus influenzae. Our purification process used differential extraction of cell envelopes with nondenaturing detergents. Solubilization of this protein was accomplished by heating a peptidoglycan-enriched subcellular fraction in the presence of one of several nondenaturing detergents at 55-60 degrees C. The purified protein migrated as a single band, with a Mr approximately 15,000, following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein contains covalently linked fatty acids, is rich in tyrosine, but lacks methionine and tryptophan. Amino acid analysis also revealed the presence of glycerylcysteine, which has been shown to be the site of fatty acylation in other bacterial lipoproteins. Over 87% of the primary structure has been determined by sequencing high pressure liquid chromatography purified fragments derived from several endoproteinase digests. This protein belongs to a family of proteins, known as peptidoglycan associated lipoproteins, which appear to be components of the outer membranes of most Gram-negative bacteria.
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PMID:Purification and characterization of a peptidoglycan-associated lipoprotein from Haemophilus influenzae. 329 Feb 14

Nutritional mutants of Haemophilus influenzae requiring l-serine for growth were shown to be deficient in their capacity to synthesize serine-phosphate from 3-phosphoglycerate. On the basis of the correlation between this block and the requirement for an exogenous supply of the amino acid, it was concluded that the "phosphorylated" pathway is the only pathway used by H. influenzae for serine biosynthesis. Serine inhibits serine-phosphate production, thereby regulating its own synthesis in a manner analagous to the Enterobacteriaceae. A mutant strain that required either serine or tryptophan for growth was normal in serine-phosphate synthesis and regulation. It was concluded that this strain probably has a tryptophan synthetase with an increased Michaelis constant for serine.
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PMID:Serine biosynthesis and regulation in Haemophilus influenzae. 530 3

A total of 260 samples of cerebrospinal fluid received from Egypt, the United States, Canada, and South America were examined by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC) for tuberculous and other forms of lymphocytic meningitis. Thirty-four of the specimens were culture positive for M. tuberculosis, and four cerebrospinal fluid specimens of herpes meningitis were established by immunological techniques. The compound, 3-(2'-ketohexyl)-indoline, was found in about 60% of the Egyptian tuberculous specimens and none of the culture-positive American specimens. the carboxylic and hydroxy acid FPEC-GLC profiles were used effectively in conjunction with other clinical data to make the diagnosis even in the absence of 3-(2'-ketohexyl)indoline. Herpes meningitis and mixed infections of Myeobacterium tuberculosis-herpes, M. tuberculosis-leptospira, and M. tuberculosis-Haemophilus influenzae produced profiles different from each other and from pure culture cases. The color test for tuberculous meningitis was evaluated, and free tryptophan was eliminated as the source of color reaction. Indications are that 3-(2'-ketohexyl)indoline, in most cases, is not responsible for the positive color reaction. Differences in the clinical and FPEC-GLC data obtained from samples from different geographical regions are discussed.
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PMID:Frequency-pulsed electron capture gas-liquid chromatography and the tryptophan color test for rapid diagnosis of tuberculous and other forms of lymphocytic meningitis. 722 7

The adk gene from the Gram-negative pathogen Bordetella pertussis was cloned by complementing the thermosensitive Escherichia coli adk strain CR341T28. B. pertussis adenylate kinase is a 218-amino-acid protein that has high similarity with adenylate kinase from Escherichia coli and Hemophilus influenzae (57%). A distinct characteristic of enzyme from B. pertussis, not found in other bacterial adenylate kinases, is the presence of a tryptophan residue at position 185. Although distant from the catalytic site, this single tryptophan serves as a convenient probe for monitoring the binding of nucleotide substrates or analogs to the enzyme. Differential scanning calorimetry and equilibrium unfolding experiments in guanidine.HCl indicate similar stabilities for adenylate kinase from B. pertussis and E. coli. An extensive comparison between physico-chemical properties of adenylate kinase from B. pertussis and the enzyme from E. coli showed that the kinetic and structural properties of the two enzymes are very similar. However, infrared spectroscopy has allowed to identify small but significant differences in the secondary structure of the two proteins.
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PMID:Structural and physico-chemical characteristics of Bordetella pertussis adenylate kinase, a tryptophan-containing enzyme. 828 44

A Haemophilus influenzae type-b capsular polysaccharide-CRM197 protein conjugate vaccine was compared with unconjugated CRM197 and diphtheria toxin, its parent molecule. Using CD and fluorescence spectroscopy, it has been possible to observe differences in structure and stability to pH and temperature due to the G52-->E mutation in CRM197 and the 'glycosylation' of CRM197 in the conjugate. CRM197 resembles the 'open' conformation of diphtheria toxin [Blewitt, M. G., Chung, L. A. & London, E. (1985) Biochemistry 24, 5458-5464] and the attachment of poly(ribosyl-ribitol phosphate) carbohydrate chains results in a still 'more open' state, although only a small decrease in the amount of ordered structure was observed. Fluorescence spectra of gel-filtration column fractions of the conjugate suggest that material of higher apparent molecular size is in the 'more open' conformation. Conjugated CRM197 begins unfolding at slightly lower temperatures (25-35 degrees C) than native material (> 35 degrees C). In the conjugate, tryptophan residues are more accessible to the non-ionic fluorescence quencher acrylamide at 35 degrees C. The conformational change observed at pH4-6 for diphtheria toxin is also observed for CRM197, but in the conjugate begins at higher pH. This may result from the presence of charged oligosaccharide residues on the surface or the conjugation methods used. The consequences of these changes in conformation and solution behaviour of the carrier protein in terms of its ability to induce a protective, T-cell-dependent response to H. influenzae polysaccharide remain to be determined.
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PMID:Comparison of the diphtheria mutant toxin, CRM197, with a Haemophilus influenzae type-b polysaccharide-CRM197 conjugate by optical spectroscopy. 920 20

Haemophilus influenzae elaborates a surface protein called Hap, which is associated with the capacity for intimate interaction with cultured epithelial cells. Expression of hap results in the production of three protein species: outer membrane proteins of approximately 155 kDa and 45 kDa and an extracellular protein of approximately 110 kDa. The 155 kDa protein corresponds to full-length mature Hap (without the signal sequence), and the 110 kDa extracellular protein represents the N-terminal portion of mature Hap (designated Haps). In the present study, we examined the mechanism of processing and secretion of Hap. Site-directed mutagenesis suggested that Hap is a serine protease that undergoes autoproteolytic cleavage to generate the 110 kDa extracellular protein and the 45 kDa outer membrane protein. Biochemical analysis confirmed this conclusion and established that cleavage occurs on the bacterial cell surface. Determination of N-terminal amino acid sequence and mutagenesis studies revealed that the 45 kDa protein corresponds to the C-terminal portion of Hap, starting at N1037. Analysis of the secondary structure of this protein (designated Hap beta) predicted formation of a beta-barrel with an N-terminal transmembrane alpha-helix followed by 14 transmembrane beta-strands. Additional analysis revealed that the final beta-strand contains an amino acid motif common to other beta-barrel outer membrane proteins. Upon deletion of this entire C-terminal consensus motif, Hap could no longer be detected in the outer membrane, and secretion of Haps was abolished. Deletion or complete alteration of the final three amino acid residues had a similar but less dramatic effect, suggesting that this terminal tripeptide is particularly important for outer membrane localization and/or stability of the protein. In contrast, isolated point mutations that disrupted the amphipathic nature of the consensus motif or eliminated the C-terminal tryptophan had no effect on outer membrane localization of Hap or secretion of Haps. These results provide insight into a growing family of Gram-negative bacterial exoproteins that are secreted by an IgA1 protease-like mechanism; in addition, they contribute to a better understanding of the structural determinants of targeting of beta-barrel proteins to the bacterial outer membrane.
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PMID:Structural determinants of processing and secretion of the Haemophilus influenzae hap protein. 940 21

Among strains of Haemophilus influenzae, the ability to catabolize tryptophan (as detected by indole production) varies and is correlated with pathogenicity. Tryptophan catabolism is widespread (70 to 75%) among harmless respiratory isolates but is nearly universal (94 to 100%) among strains causing serious disease, including meningitis. As a first step in investigating the relationship between tryptophan catabolism and virulence, we have identified genes in pathogenic H. influenzae which are homologous to the tryptophanase (tna) operon of Escherichia coli. The tna genes are located on a 3.1-kb fragment between nlpD and mutS in the H. influenzae type b (Eagan) genome, are flanked by 43-bp direct repeats of an uptake signal sequence downstream from nlpD, and appear to have been inserted as a mobile unit within this sequence. The organization of this insertion is reminiscent of pathogenicity islands. The tna cluster is found at the same map location in all indole-positive strains of H. influenzae surveyed and is absent from reference type d and e genomes. In contrast to H. influenzae, most other Haemophilus species lack tna genes. Phylogenetic comparisons suggest that the tna cluster was acquired by intergeneric lateral transfer, either by H. influenzae or a recent ancestor, and that E. coli may have acquired its tnaA gene from a related source. Genomes of virulent H. influenzae resemble those of pathogenic enterics in having an island of laterally transferred DNA next to mutS.
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PMID:The tryptophanase gene cluster of Haemophilus influenzae type b: evidence for horizontal gene transfer. 942

In bacteria, synonymous codon usage can be considerably affected by base composition at neighboring sites. Such context-dependent biases may be caused by either selection against specific nucleotide motifs or context-dependent mutation biases. Here we consider the evolutionary conservation of context-dependent codon bias across 11 completely sequenced bacterial genomes. In particular, we focus on two contextual biases previously identified in Escherichia coli; the avoidance of out-of-frame stop codons and AGG motifs. By identifying homologues of E. coli genes, we also investigate the effect of gene expression level in Haemophilus influenzae and Mycoplasma genitalium. We find that while context-dependent codon biases are widespread in bacteria, few are conserved across all species considered. Avoidance of out-of-frame stop codons does not apply to all stop codons or amino acids in E. coli, does not hold for different species, does not increase with gene expression level, and is not relaxed in Mycoplasma spp., in which the canonical stop codon, TGA, is recognized as tryptophan. Avoidance of AGG motifs shows some evolutionary conservation and increases with gene expression level in E. coli, suggestive of the action of selection, but the cause of the bias differs between species. These results demonstrate that strong context-dependent forces, both selective and mutational, operate on synonymous codon usage but that these differ considerably between genomes.
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PMID:Evolutionary lability of context-dependent codon bias in bacteria. 1075 70

Computational comparative techniques were applied to analysis of the aromatic amino acid regulons in gamma-proteobacteria. This resulted in characterization of the TrpR and TyrR regulons in the genomes of Yersinia pestis, Haemophilus influenzae, Vibrio cholerae and other bacteria and identification of new members of the PhhR regulon in the genome of Pseudomonas aeruginosa. Candidate attenuators were constructed for all studied genomes, including the trpBA operon of the very distantly related bacterium Chlamidia trachomatis. The pheA attenuator of Y. pestis is an integration site for the insertion element IS-200. It was shown that the triplication of the DAHP-synthase genes occurred prior to the divergence of families Enterobacteriaceae, Vibrionaceae and Alteromonadaceae. The candidate allosteric control site of the DAHP-syntheases was identified. This site is deteriorated in AroH of Buchnera sp. APS. The known DAHP-synthase of Bordetella pertussis is likely to be feedback-inhibited by phenylalanine, and the DAHP-synthase of Corynebacterium glutamicum could be inhibited by tyrosine. Overall, the most extensive regulation was observed in Escherichia coli, whereas the regulation in other genomes seems to be less developed. At the extreme, the tryptophan production in the aphid endosymbiont Buchnera sp. APS is free from transcriptional, attenuation, and allosteric control.
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PMID:Regulation of aromatic amino acid biosynthesis in gamma-proteobacteria. 1154 72

In the study described here, we have taken steps to characterize the YjeE protein, an Escherichia coli protein of unknown function that is essential for bacterial viability. YjeE represents a protein family whose members are broadly conserved in bacteria, absent from eukaryotes and contain both Walker A and B motifs, characteristic of P-loop ATPases. We have revisited the dispensability of the yjeE gene in E. coli and describe efforts to probe the function of the YjeE protein with in vitro biochemistry. We have looked critically for ATPase activity in the recombinant E. coli protein and have made vigilant use of site-directed variants in the Walker A [K41A (Lys41-->Ala) and T42A] and putative Walker B (D80Q) motifs. We noted that any hydrolysis of ATP by the wild-type E. coli protein might be attributed to background ATPase, since it was not appreciably different from that of the variants. To overcome potential contaminants, we turned to crystalline pure YjeE protein from Haemophilus influenzae that was found to hydrolyse ATP at a slow rate (kcat=1 h(-1)). We have also shown high-affinity binding to YjeE by ADP using equilibrium dialysis (K(d)=32 microM) and by fluorescence resonance energy transfer from a conserved tryptophan in YjeE to a fluorescent derivative of ADP, 2'-/3'-O-(N-methylanthraniloyl)adenosine 5'-O-diphosphate (K(d)=8 microM). Walker motif variants were notably impaired for ADP binding and T42A and D80Q mutations in yjeE were incapable of complementing the yjeE deletion strain.
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PMID:Probing the active site of YjeE: a vital Escherichia coli protein of unknown function. 1532 1


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