Aspergillus fumigatus / Iron

Discussion in 'Health and medical' started by Doe, Feb 27, 2004.

  1. Doe

    Doe Guest

    Infect Immun. 2004 Mar;72(3):1402-8. Related Articles, Links

    Survival of Aspergillus fumigatus in Serum Involves Removal of Iron from Transferrin: the Role of
    Siderophores.

    Hissen AH, Chow JM, Pinto LJ, Moore MM.

    Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A
    1S6, Canada.

    Aspergillus fumigatus is a filamentous fungus which can cause invasive disease in immunocompromised
    individuals. A. fumigatus can grow in medium containing up to 80% human serum, despite very low
    concentrations of free iron. The purpose of this study was to determine the mechanism by which A.
    fumigatus obtains iron from the serum iron-binding protein transferrin. In iron-depleted minimal
    essential medium (MEM), A. fumigatus growth was supported by the addition of holotransferrin
    (holoTf) or FeCl(3) but not by the addition of apotransferrin (apoTf). Proteolytic degradation of
    transferrin by A. fumigatus occurred in MEM-serum; however, transferrin degradation did not occur
    until late logarithmic phase. Moreover, transferrin was not degraded by A. fumigatus incubated in
    MEM-holoTf. Urea polyacrylamide gel electrophoresis showed that in MEM-holoTf, holoTf was completely
    converted to apoTf by A. fumigatus. In human serum, all of the monoferric transferrin was converted
    to apoTf within 8 h. Siderophores were secreted by A. fumigatus after 8 h of growth in MEM-serum and
    12 h in MEM-holoTf. The involvement of small molecules in iron acquisition was confirmed by the fact
    that transferrin was deferrated by A. fumigatus even when physically separated by a 12-kDa-cutoff
    membrane. Five siderophores were purified from A. fumigatus culture medium, and the two major
    siderophores were identified as triacetylfusarinine C and ferricrocin. Both triacetylfusarinine C
    and ferricrocin removed iron from holoTf with an affinity comparable to that of ferrichrome. These
    data indicate that A. fumigatus survival in human serum in vitro involves siderophore-mediated
    removal of iron from transferrin. Proteolytic degradation of transferrin may play a secondary role
    in iron acquisition.

    PMID: 14977945 [PubMed - in process]

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