Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P43026 (lipopolysaccharide)
 62,215 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have determined that gene HI#1181 of Haemophilus influenzae is a homolog of Escherichia coli gmhA (previously designated lpcA) (J. S. Brooke and M. A. Valvano, J. Biol. Chem. 271:3608-3614, 1996), which encodes a phosphoheptose isomerase catalyzing the first step of the biosynthesis of ADP-L-glycero-D-manno heptose. Mutations in this gene are associated with a heptoseless core lipopolysaccharide which determines an increased outer membrane permeability to hydrophobic compounds. The cloned H. influenzae gmhA restored the synthesis of a complete core in the gmhA-deleted E. coli strain chi711. Amino acid sequence comparisons of the GmhA proteins of E. coli and H. influenzae with other proteins in the databases revealed the existence of a novel family of phosphosugar a1do-keto isomerases.
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PMID:Molecular cloning of the Haemophilus influenzae gmhA (lpcA) gene encoding a phosphoheptose isomerase required for lipooligosaccharide biosynthesis. 865 17

A total of 117 consecutive patients with primary antibody deficiencies were followed for up to 5 years with regard to acute respiratory tract infections. Nontypeable Haemophilus influenzae (NTHI) was the sole pathogen in 61% (202/330) of the samples from which a potential pathogen was recovered. Common variable immunodeficiency (CVI) was the most prevalent condition (27/39 patients) in the group where H. influenzae was isolated. In patients where H. influenzae was not found only 9/78 patients had CVI. 49 of these 78 patients had isolated IgG3 or IgA deficiency. Both of these entities seemed to be associated with a lower prevalence of NTHI infections. 13 of 18 patients with at least 2 isolates of NTHI were colonized with the same strain from 3 to 43 months as shown by total genomic DNA-fingerprinting. Recurrent symptomatic infections occurred in these patients despite substitution therapy with gammaglobulins and repeated antibiotic treatments. All but 2 of the 224 H. influenzae isolates were beta-lactamase negative and sensitive to ampicillin. The use of 10 lipopolysaccharide-specific monoclonal antibodies in a whole cell ELISA showed that the LPS-epitopes on the 224 H. influenzae isolates from the hypogammaglobulinemic group were very similar to 499 NTHI isolates from immunocompetent patients with respiratory infections. One may therefore conclude that i) patients with CVI, were prone to be permanently colonized with NTHI, and ii) the colonizing bacteria were ordinary strains showing the same LPS-phenotypes as those strains that cause acute respiratory tract infections in immunocompetent individuals.
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PMID:Characterization of Haemophilus influenzae isolates from the respiratory tract of patients with primary antibody deficiencies: evidence for persistent colonizations. 865 61

The whole genome sequence (1.83 Mbp) of Haemophilus influenzae strain Rd was searched to identify tandem oligonucleotide repeat sequences. Loss or gain of one or more nucleotide repeats through a recombination-independent slippage mechanism is known to mediate phase variation of surface molecules of pathogenic bacteria, including H. influenzae. This facilitates evasion of host defenses and adaptation to the varying microenvironments of the host. We reasoned that iterative nucleotides could identify novel genes relevant to microbe-host interactions. Our search of the Rd genome sequence identified 9 novel loci with multiple (range 6-36, mean 22) tandem tetranucleotide repeats. All were found to be located within putative open reading frames and included homologues of hemoglobin-binding proteins of Neisseria, a glycosyltransferase (lgtC gene product) of Neisseria, and an adhesin of Yersinia. These tetranucleotide repeat sequences were also shown to be present in two other epidemiologically different H. influenzae type b strains, although the number and distribution of repeats was different. Further characterization of the lgtC gene showed that it was involved in phenotypic switching of a lipopolysaccharide epitope and that this variable expression was associated with changes in the number of tetranucleotide repeats. Mutation of lgtC resulted in attenuated virulence of H. influenzae in an infant rat model of invasive infection. These data indicate the rapidity, economy, and completeness with which whole genome sequences can be used to investigate the biology of pathogenic bacteria.
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PMID:DNA repeats identify novel virulence genes in Haemophilus influenzae. 885 19

A novel lipopolysaccharide (LPS) biosynthesis gene, lic2B, which is required for the biosynthesis of a phase-variable LPS structure expressed by Haemophilus influenzae RM7004 is described. The product of this gene is homologous to Lic2A and the recently described LPS biosynthetic enzymes, LgtB from Neisseria gonorrhoea and LgtE from Neisseria meningitidis, and LpsA from Pasteurella haemolytica. Of this family of enzymes only Lic2A contains the repetitive tetrapeptide motif (SINQ)(n) encoded by multiple tandem repeats of 5'-CAAT-3'. This observation suggested that (SINQ)(n) might not be a prerequisite for the catalytic activity of this protein. To address this hypothesis, we deleted the 5'-CAAT-3' repeats from lic2A so that the protein encoded by the modified gene was analogous to Lic2B. This mutation had no apparent effect on the overall apparent molecular weight of LPS as judged by Tricine-SDS-PAGE and did not affect ability to react with monoclonal antibody 4C4. It was therefore concluded that (SINQ)(n) is not a prerequisite for the enzymatic function of Lic2A and that the 5'-CAAT-3' repeats in lic2A function solely as a mechanism for generating phase variation. This observation suggested that wide variation in the number of 5'-CAAT-3' repeats might be tolerated in lic2A, and this was confirmed by surveying the number of 5'-CAAT-3' repeats in a range of different H. influenzae strains. The predicted secondary structure of (SINQ)(n) indicates that it forms a highly flexible random coiled structure, which is unlikely to impede formation of the domains that may be required for catalytic activity. This characteristic is also a feature of repetitive tetrapeptides encoded by other tetrameric repeats located within coding sequences present on the chromosome of H. influenzae Rd.
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PMID:Tandem repeats of the tetramer 5'-CAAT-3' present in lic2A are required for phase variation but not lipopolysaccharide biosynthesis in Haemophilus influenzae. 886 Dec 14

The tetrameric repeat units 5'-CAAT-3' and 5'-GCAA-3' are associated with phase variable expression of lipopolysaccharide biosynthetic genes in Haemophilus influenzae. Four other tetrameric repeat units have also been reported from H. influenzae strain Rd, 5'-CAAC-3', 5'-GACA-3', 5'-AGCT-3', and 5'-TTTA-3', which are also associated with putative virulence factors. Using oligonucleotide probes corresponding to five tandem copies of each of these tetramers, we have screened three strains of Neisseria meningitidis and one each of Neisseria gonorrhoeae, Neisseria lactamica, Haemophilus parainfluenzae, Bordetella pertussis, Bordetella parapertussis, Bordetella bronchiceptica and Moraxella catarrhalis for the presence of these motifs. We have demonstrated the presence of multiple copies of the 5'-GCAA-3' motif in all the Neisseria strains tested, and also the repeated motif 5'-CAAC-3' in M. catarrhalis. We have further demonstrated by Southern blot analysis that the 5'-CAAC-3' repeats detected in M. catarrhalis are probably associated with the same genes as in H. influenzae, but that the 5'-GCAA-3' motifs in N. meningitidis are not. The use of characterised tetrameric DNA sequences as hybridisation probes may prove useful in the identification of novel phase variable virulence determinants in organisms other than H. influenzae.
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PMID:Tetrameric repeat units associated with virulence factor phase variation in Haemophilus also occur in Neisseria spp. and Moraxella catarrhalis. 893 64

Mouse monoclonal antibodies MAHI 4 and MAHI 10 reactive with Haemophilus influenzae lipopolysaccharide (LPS), were generated by fusing mouse myeloma cells with spleen cells of mice immunized with H. influenzae strain RM.7004-XP-1. The antibody MAHI 4 reacted in whole-cell enzyme immunoassay (EIA) and colony-dot-immunoblotting with 20 of 123 H. influenzae strains and to a few other human Haemophilus spp. and Neisseria spp., but not to any Bordetella pertussis, B. parapertussis, Aeromonas spp. or Moraxella catarrhalis strains tested. This suggests a specific epitope accessible to recognition in just a few strains. This conclusion was supported by the data on binding of MAHI 4 to only three of 18 H. influenzae LPSs tested, but not to any Haemophilus ducreyi or enterobacterial LPSs. The antibody MAHI 10 bound to 80 of 123 strains of H. influenzae and to a few strains of Neisseria spp. and M. catarrhalis as evaluated by EIA and colony-dot-immunoblotting, which suggests an epitope accessible to recognition in 65% of the H. influenzae strains tested. The antibody MAHI 10 reacted with 10 of 18 H. influenzae LPSs as determined by EIA. By using polysaccharides, obtained after both mild acidic hydrolysis, strong alkali treatment, and dephosphorylation, as inhibitors of the antibodies binding to H. influenzae LPS antigens it was shown that phosphate groups were essential for the binding of MAHI 10 to LPS but they did not affect antigenic recognition by MAHI 4. None of the monoclonal antibodies bound to isolated lipid A, but the aggregation caused by the fatty acids of lipid A was essential for optimum epitope recognition. Enzymatic treatment of homologous LPSs with galactose-oxidase led to products which were between 20 to 30 times less effective as inhibitors of the binding of the MAHI 4 than the native LPSs. Taken together the results indicate that MAHI 4 has the following pentasaccharide as the epitope Gal beta 1-->2 Hep alpha 1-->2Hep alpha 1-->3Hep alpha 1--> Kdo(P). These results emphasize the importance of the terminal beta-Gal residue in the definition of the MAHI 4 specificity, and of the terminal phosphorylated saccharide residues of some of the Haemophilus LPSs for the MAHI 10 specificity.
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PMID:Monoclonal antibodies against Haemophilus influenzae lipopolysaccharides: clone MAHI 4 binding to a pentasaccharide containing terminal beta-Gal residues and clone MAHI 10 recognizing terminal phosphorylated saccharide residues. 893 39

The availability of the complete 1.83-megabase-pair sequence of the Haemophilus influenzae strain Rd genome has facilitated significant progress in investigating the biology of H.influenzae lipopolysaccharide (LPS), a major virulence determinant of this human pathogen. By searching the H. influenzae genomic database, with sequences of known LPS biosynthetic genes from other organisms, we identified and then cloned 25 candidate LPS genes. Construction of mutant strains and characterization of the LPS by reactivity with monoclonal antibodies, PAGE fractionation patterns and electrospray mass spectrometry comparative analysis have confirmed a potential role in LPS biosynthesis for the majority of these candidate genes. Virulence studies in the infant rat have allowed us to estimate the minimal LPS structure required for intravascular dissemination. This study is one of the first to demonstrate the rapidity, economy and completeness with which novel biological information can be accessed once the complete genome sequence of an organism is available.
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PMID:Use of the complete genome sequence information of Haemophilus influenzae strain Rd to investigate lipopolysaccharide biosynthesis. 897 16

Choline, although not a nutritional requirement for Haemophilus influenzae, is taken up from the growth medium and incorporated into its lipopolysaccharide (LPS). Incorporated choline is in the form of phosphorylcholine (ChoP) based on the reactivity with the monoclonal antibody with specificity for this structure, TEPC-15. Incorporation of [3H]choline from the growth medium and expression of the TEPC-15 epitope undergo high-frequency phase variation, characteristic of other LPS structures in this species. The expression and phase variation of ChoP require a previously identified locus involved in LPS biosynthesis, lic1. The first gene in lic1, licA, contains a translational switch based on variation in the number of intragenic tandem repeats of the sequence 5'-CAAT-3'. The full-length LicA polypeptide resembles choline kinases of eucaryotes, suggesting that the pathway for choline incorporation into the H. influenzae glycolipid has similarities to the pathway for choline incorporation in eucaryotic lipid synthesis. The display of ChoP, a host-like structure, renders the organism more rather than less susceptible to the bactericidal activity of human serum. The increased serum sensitivity of variants with ChoP correlates with higher serum immunoglobulin G titers to LPS containing this structure. ChoP appears to be a cell surface feature common to a number of pathogens of the human respiratory tract, including Streptococcus pneumoniae and mycoplasmas. In the case of H. influenzae, its primary contribution to pathogenesis does not appear to be antigenic variation to evade host humoral clearance mechanisms.
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PMID:Decoration of lipopolysaccharide with phosphorylcholine: a phase-variable characteristic of Haemophilus influenzae. 903 1

Haemophilus influenzae is an important human pathogen. The lipooligosaccharide (LOS) of H. influenzae has been implicated as a virulence determinant. To better understand the assembly of LOS in nontypeable H. influenzae (NtHi), we have cloned and characterized the rfaD and rfaF genes of NtHi 2019, which encode the ADP-L-glycero-D-manno-heptose-6-epimerase and heptosyltransferase II enzymes, respectively. This cloning was accomplished by the complementation of Salmonella typhimurium lipopolysaccharide (LPS) biosynthesis gene mutants. These deep rough mutants are novobiocin susceptible until complemented with the appropriate gene. In this manner, we are able to use novobiocin resistance to select for specific NtHi LOS inner core biosynthesis genes. Such a screening system yielded a plasmid with a 4.8-kb insert. This plasmid was able to complement both rfaD and rfaF mutants of S. typhimurium. The LPS of these complemented strains appeared identical to the wild-type Salmonella LPS. The genes encoding the rfaD and rfaF genes from NtHi 2019 were sequenced and found to be similar to the analogous genes from S. typhimurium and Escherichia coli. The rfaD gene encodes a polypeptide of 35 kDa and the rfaF encodes a protein of 39 kDa, as demonstrated by in vitro transcription-translation studies. Isogenic mutants which demonstrated truncated LOS consistent with inner core biosynthesis mutants were constructed in the NtHi strain 2019. Primer extension analysis demonstrated the presence of a strong promoter upstream of rfaD but suggested only a very weak promoter upstream of rfaF. Complementation studies, however, suggest that the rfaF gene does have an independent promoter. Mass spectrometric analysis shows that the LOS molecules expressed by H. influenzae rfaD and rfaF mutant strains have identical molecular masses. Additional studies verified that in the rfaD mutant strain, D-glycero-D-manno-heptose is added to the LOS molecule in place of the usual L-glycero-D-manno-heptose. Finally, the genetic organizations of the inner core biosynthesis genes of S. typhimurium, E. coli, and several strains of H. influenzae were examined, and substantial differences were uncovered.
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PMID:Identification of the ADP-L-glycero-D-manno-heptose-6-epimerase (rfaD) and heptosyltransferase II (rfaF) biosynthesis genes from nontypeable Haemophilus influenzae 2019. 911 77

The phosphorylcholine (PC) determinant in Streptococcus pneumoniae is known to be linked to the cell wall polysaccharides (C-Ps) and to the lipoteichoic acid (LTA) (Forssman antigen) of the plasma membrane. Western blotting with two PC specific murine monoclonal antibodies (MAbs) designated 145,F-2 (IgM) and 147,A-1 (IgA) showed a similar ladder-like pattern for all examined strains of S. pneumoniae and Streptococcus mitis. Purified antigens run in parallel indicated that this ladder pattern is due to the PC of LTA. Unlike other techniques, Western blotting thus enables the identification of only one of the streptococcal structures carrying the PC epitope. Gram-negative organisms were also examined, and six of 11 Haemophilus influenzae strains reacted with the MAbs. For this species, unlike the streptococci, only one fast moving band was detected. Analyses by thin-layer chromatography (TLC) detected the PC epitope in lipopolysaccharide (LPS) fraction from H. influenzae. Some strains of the Neisseriaceae family were also positive by Western blotting, but TLC and immunostaining did not detect the PC determinant in LPS.
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PMID:Detection of the phosphorylcholine epitope in streptococci, Haemophilus and pathogenic Neisseriae by immunoblotting. 918 87


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