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   Mol Microbiol 1999 Apr;32(2):403-14
   
The Yfe system of Yersinia pestis transports iron and manganese and is required
for full virulence of plague.

    Bearden SW, Perry RD
    
   Department of Microbiology and Immunology, MS415 Chandler Medical
   Center, University of Kentucky, Lexington, KY 40536-0084, USA.
   
   Iron acquisition in Yersinia pestis is fundamental to the success of
   plague pathogenesis. We have previously identified an approximately
   5.6 kb region (yfe) of Y. pestis genomic DNA, capable of restoring
   iron-deficient growth but not siderophore production to an Escherichia
   coli mutant (SAB11) incapable of synthesizing the siderophore,
   enterobactin. The yfe locus of Y. pestis, found in both pigmented
   (Pgm+) and nonpigmented (Pgm-) strains, comprises five genes arranged
   in two distinct operons (yfeA-D and yfeE ). The larger of these,
   yfeABCD, encodes an ABC transport system, whose expression is iron and
   Fur regulated and is repressed in cells grown in the presence of
   manganese. Cells from a Pgm-, Yfe- (DeltayfeAB ) mutant strain of Y.
   pestis exhibited reduced transport of both 55Fe and 54Mn. Furthermore,
   cells containing an intact yfe locus showed reduced 55Fe uptake when
   competing amounts of MnCl2 or ZnCl2 were present, whereas 54Mn uptake
   was inhibited by FeCl3 but not by ZnCl2. Similarly, yfe mutants of Y.
   pestis exhibited growth defects on media supplemented with the iron
   chelators 2,2'-dipyridyl or conalbumin. These growth defects were not
   relieved by supplementation with MnCl2. A ybt-, DeltayfeAB mutant of
   Y. pestis was completely avirulent in mice infected intravenously
   (LD50 > 1.7 x 107 cfu) compared with its parental ybt-, yfe+ strain,
   which had an LD50 of < 12. In addition, compared with its ybt+, yfe+
   parent, a ybt+, DeltayfeAB mutant of Y. pestis had an approximately
   100-fold increase in the LD50 from a subcutaneous route of infection.
   These data suggest that the Yfe and Ybt systems may function
   effectively to accumulate iron during different stages of the
   infectious process of bubonic plague.
   
   PMID: 10231495, UI: 99248418
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   Mikrobiol Zh 1989 Jan-Feb;51(1):13-8
   
[Iron assimilation by Yersinia pestis on iron-deficient media].

   [Article in Russian]
   
    Rublev BD, Kagramanov VS, Bursha OS, Ryzhkov VI
    
   The growth of plague bacteria may be limited by the level of iron
   concentration in the nutrient medium. The virulent strains of the
   plague microbe possess the more pronounced mechanism of iron
   assimilation as compared to the vaccine strain. The iron ions are
   extracted by the virulent and vaccine strains only under the cell
   surface contact with the iron-saturated transferrin. The iron-sorbing
   function is peculiar to the plague microbe cell walls which is
   pronounced more strongly in the virulent strains.
   
   PMID: 2524638, UI: 89261403
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