Fate of Labeled Hydroxamates During Iron Transport from Hydroxamate-Iron Chelates
AUTOR(ES)
Arceneaux, Jean E. L.
RESUMO
The fate of the hydroxamic acid-iron transport cofactors during iron uptake from the 59Fe3+ chelates of the 3H-labeled hydroxamates schizokinen and aerobactin was studied by assay of simultaneous incorporation of both 59Fe3+ and 3H. In the schizokinen-producing organism Bacillus megaterium ATCC 19213 transport of 59Fe3+ from the 3H-schizokinen-59Fe3+ chelate at 37 C was accompanied by rapid uptake and release (within 2 min) of 3H-schizokinen, although 3H-schizokinen discharge was temperature-dependent and did not occur at 0 C. In the schizokinen-requiring strain B. megaterium SK11 similar release of 3H-schizokinen occurred only at elevated concentrations of the double-labeled chelate; at lower chelate concentrations, 3H-schizokinen remained cell-associated. Temperature-dependent uptake of deferri (iron-free) 3H-schizokinen to levels equivalent to those incorporated from the chelate form was noted in strain SK11, but strain ATCC 19213 showed only temperature-independent binding of low concentrations of deferri 3H-schizokinen. These results indicate an initial temperature-independent binding of the ferric hydroxamate which is followed rapidly by temperature-dependent transport of the chelate into the cell and an enzyme catalyzed separation of iron from the chelate. The resulting deferri hydroxamate is discharged from the cell only when a characteristic intracellular concentration of the hydroxamate is exceeded, which happens in the schizokinen-requiring strain only at elevated concentrations of the chelate. This strain also appears to draw the deferri hydroxamate into the cell by a temperature-dependent mechanism. The aerobactin-producing organism Aerobacter aerogenes 62-1 also demonstrated rapid initial uptake and temperature-dependent discharge of 3H-aerobactin during iron transport from 3H-aerobactin-59Fe3+, suggesting a similar ferric hydroxamate transport system in this organism.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=246337Documentos Relacionados
- Hydroxamate Recognition During Iron Transport from Hydroxamate-Iron Chelates
- Hydroxamate-mediated transport of iron controlled by ColV plasmids.
- Selective absorption of iron from iron chelates by soybean plants 1
- Ferric hydroxamate transport without subsequent iron utilization in Bacillus megaterium.
- Identification and Characterization of a Membrane Permease Involved in Iron-Hydroxamate Transport in Staphylococcus aureus
