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)

To investigate the mechanisms of iron acquisition in avian haemophili, strains of Haemophilus paragallinarum and H. avium were tested for siderophore production and utilization of transferrin iron for growth. No evidence of siderophore production was detected in either of these species using a functional screening assay. H. paragallinarum, but not strains of H. avium, was able to acquire iron from 30% saturated chicken and turkey transferrins but not from human, porcine, or bovine transferrins. In response to iron limitation, H. paragallinarum expressed four iron-regulated outer-membrane proteins of 53, 62, 66, and 94 kilodaltons (kDa). Only the 53- and 94-kDa proteins were detected in the H. avium strains. Using affinity methods, the 94- and 53-kDa proteins were isolated specifically by chicken or turkey transferrin, indicating that they may be equivalent to transferrin binding proteins (TBP1 and TBP2, respectively) isolated from other bacterial species. The isolation of the 62- and 66-kDa proteins in association with TBP1 and TBP2 under less stringent washing conditions only in H. paragallinarum implicates these proteins in the iron acquisition process.
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PMID:Correlation between the ability of Haemophilus paragallinarum to acquire ovotransferrin-bound iron and the expression of ovotransferrin-specific receptors. 141 95

Haemophilus influenzae type b acquires transferrin-bound iron via a siderophore-independent mechanism involving direct contact between the human iron-binding glycoprotein and the bacterial cell surface. Evidence has accumulated to show that the transferrin receptor consists of at least two iron-regulated outer membrane transferrin-binding proteins (TBPs), of which one has a molecular mass of around 100 kDa (TBP1) and the other has a molecular mass of 60 to 90 kDa (TBP2). In H. influenzae type b strain Eagan, proteins of 76, 90, and 107 kDa appear to be involved in transferrin binding. To determine whether these TBPs are expressed during growth in vivo, strain Eagan was recovered without subculture from the intraperitoneal cavities of infected infant rats. By using a dot blot assay, outer membranes prepared from these in vivo-grown bacteria, unlike those grown in iron-sufficient broth, bound human transferrin and produced the 76-, 90-, and 107-kDa TBPs. Immunoblotting experiments using convalescent sera from infected rats also revealed the presence of antibodies to the 76- and 90-kDa strain Eagan TBPs. In addition, convalescent sera from three of four patients recovering from H. influenzae type b meningitis contained antibodies to the 90- and 105-kDa TBPs of the corresponding infecting strain. Furthermore, fresh clinical isolates of H. influenzae type b recovered from blood and cerebrospinal fluid showed constitutive expression of the TBPs, which became iron regulated only after prolonged in vitro subculture on iron-sufficient medium. This contrasted with the laboratory-adapted Eagan strain, in which the TBPs remained iron regulated even after animal passage. These findings indicate that the H. influenzae type b transferrin receptor is expressed during experimental animal and human infections.
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PMID:Evidence for in vivo expression of transferrin-binding proteins in Haemophilus influenzae type b. 161 63

The NH2-terminal amino sequence through the first 20 amino acids was obtained for transferrin-binding protein (TBP)1 from three strains of Neisseria meningitidis. These were identical except for a glutamine to a glycine substitution at residue 6 in one case. The sequences of the NH2-terminal 20 amino acids of TBP2 from the same three strains were also determined; one TBP2 had a M(r) of 68,000 and the other two of 78,000. Sequences were identical up to residue 13 in all three proteins. Peptides based on the NH2-terminal sequences of TBP1 and 2 were synthesized, linked to Keyhole Limpet haemocyanin and used to raise antibodies in rabbits. Anti-peptide antibodies cross-reacted on immunoblotting with the respective TBPs from all meningococcal strains tested, as well as with those from N. gonorrhoeae, suggesting that the NH2-terminals of these proteins are well conserved in the Neisseria. Neither anti-peptide serum reacted with the analogous TBP1 and 2 from Haemophilus influenzae, although common epitopes have previously been shown to exist.
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PMID:Antigenic relationships of transferrin-binding proteins from Neisseria meningitidis, N. gonorrhoeae and Haemophilus influenzae: cross-reactivity of antibodies to NH2-terminal peptides. 831 86