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

Although Haemophilus influenzae requires heme for growth, the source of heme during invasive infections is not known. We compared heme, lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin as sources of heme for growth in defined media. The minimum concentration of heme permitting unrestricted growth of strain E1a, an H. influenzae type b isolate from cerebrospinal fluid, was 0.02 micrograms/ml. Using molar equivalents of heme as lactoperoxidase, catalase, cytochrome c, myoglobin, and hemoglobin, we determined that myoglobin and hemoglobin permitted unrestricted growth at this concentration. To determine the ability of host defenses to sequester heme from H. influenzae, we used affinity chromatography to purify human haptoglobin and hemopexin, serum proteins which bind hemoglobin and heme. Plate assays revealed that 12 strains of H. influenzae acquired heme from hemoglobin, hemoglobin-haptoglobin, heme-hemopexin, and heme-albumin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of outer membrane proteins of strain E1a grown in heme-replete and heme-restricted conditions revealed a heme-repressible outer membrane protein with an apparent molecular mass of 38 kilodaltons. These results demonstrated that, unlike Escherichia coli, H. influenzae may acquire heme from hemoglobin-haptoglobin. H. influenzae also may acquire heme from hemopexin and albumin, which have not been previously investigated. The role of outer membrane proteins in the acquisition of heme is not yet clear.
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PMID:Protein sources of heme for Haemophilus influenzae. 302 98

Binding of biotinylated human hemoglobin to Haemophilus influenzae was detected when organisms were grown in heme-deplete, but not heme-replete, conditions. Hemoglobin binding was completely inhibited by a 100-fold excess of unlabelled human hemoglobin or human hemoglobin complexed with human haptoglobin. Binding was only partially inhibited by rat hemoglobin, bovine hemoglobin, human globin, and bovine globin, and not at all by heme, human serum albumin, bovine serum albumin, human transferrin, or myoglobin. Hemoglobin binding was saturable at 16-20 ng of hemoglobin per 10(9) cfu. Binding of human hemoglobin was detected in serotypes a-f and serologically non-typable strains of H. influenzae, as well as Haemophilus haemolyticus but not Haemophilus parainfluenzae, Haemophilus aphrophilus, Haemophilus parahaemolyticus, or Escherichia coli.
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PMID:Binding of human hemoglobin by Haemophilus influenzae. 802 Jul 48

The output from the molecular biology revolution has grown steadily and logarithmically from the first protein sequence, insulin (Ryle AP et al 1955 Biochem J 60:541-556), the first three-dimensional atomic structure of a macromolecule, myoglobin (Kendrew JC et al 1960 Nature 185:422-427), the first DNA gene sequence, phi X174 gene J (Sanger F et al 1977 Nature 265:687-695) and the first genome sequence for a free-living organism, Haemophilus influenzae (Fleischmann RD et al 1995 Science 269:496-512) to the current situation where the output rate is close to one new gene sequence every few minutes, several new three-dimensional structures a day and a new (bacterial) genome completed every few months. Those working in this field must readjust their horizons to this changing situation every year or two. In the area of three-dimensional structure of macromolecules and macromolecular assemblies, the methods of X-ray crystallography, nuclear magnetic resonance and electron microscopy have combined to produce powerful insights into how these molecular machines work. In this paper, I present three examples of molecular machines whose structure tells us a lot about how they work. These are the light-driven proton pump bacteriorhodopsin, the ATP synthetase molecule which contains a tiny motor and generator, and the flagellar rotary motor which provides the thrust to power physical movement of the bacterial cell. The structure itself in three-dimensional detail is thus often seen to provide the most important single insight into how things work, reducing biology to chemistry and physics. The reductionist approach in this field seems to be limited only by the accuracy by which it is possible to describe inter- and intra-molecular interactions in terms of hydrogen bonds, van der Waals interactions and electrostatic forces. At present, there is no fundamental limit in sight.
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PMID:Macromolecular structure and self-assembly. 965 14

Haemophilus influenzae has an absolute growth requirement for heme. One potential in vivo source of heme is the protein myoglobin which is found at low levels in human serum. No tested H. influenzae strain was able to use myoglobin as a heme source. However, all strains were able to utilize the heme from myoglobin when myoglobin was complexed with haptoglobin. Utilization of the haptoglobin-myoglobin complex was shown to be mediated by the previously described hemoglobin/hemoglobin-haptoglobin-binding proteins of H. influenzae.
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PMID:Utilization of myoglobin as a heme source by Haemophilus influenzae requires binding of myoglobin to haptoglobin. 1664 May 79