| ironjustice@aol.com 2006-06-04, 9:21 am |
| Burkholderia cenocepacia utilizes ferritin as an iron source.
Whitby PW, Vanwagoner TM, Springer JM, Morton DJ, Seale TW, Stull TL
J Med Microbiol. 2006 Jun ; 55(Pt 6): 661-8
Burkholderia cenocepacia is a member of the Burkholderia cepacia
complex, a group of genetically similar species that inhabit a number
of environmental niches, including the lungs of patients with cystic
fibrosis (CF). To colonize the lung, this bacterium requires a source
of iron to satisfy its nutritional requirements for this important
metal. Because of the high potential for damage in lung tissue
resulting from oxygen-iron interactions, this metal is sequestered by a
number of mechanisms that render it potentially unavailable to invading
micro-organisms. Such mechanisms include the intracellular and
extracellular presence of the iron-binding protein ferritin. Ferritin
has a highly stable macromolecular structure and may contain up to 4500
iron atoms per molecule. To date, there has been no known report of a
pathogenic bacterial species that directly utilizes iron sequestered by
this macromolecule. To examine the ability of ferritin to support
growth of B. cenocepacia J2315, iron-deficient media were supplemented
with different concentrations of ferritin and the growth kinetics
characterized over a 40 h period. The results indicated that B.
cenocepacia J2315 utilizes iron bound by ferritin. Further studies
examining the mechanisms of iron uptake from ferritin indicated that
iron utilization results from a proteolytic degradation of this
otherwise stable macromolecular structure. Since it is known that the
ferritin concentration is significantly higher in the CF lung than in
healthy lungs, this novel iron-acquisition mechanism may contribute to
infection by B. cenocepacia in people with CF.
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