Iron-uptake in the Euryarchaeon Halobacterium salinarum.
Iron-uptake is well studied in a plethora of pro- and eukaryotic organisms with the exception of Archaea, which thrive mainly in extreme environments. In this study, the mechanism of iron transport in the extremely halophilic Euryarchaeon Halobacterium salinarum strain JW 5 was analyzed. Under low-iron growth conditions no siderophores were detectable in culture supernatants. However, various xenosiderophores support growth of H. salinarum. In [55Fe]-[14C] double-label experiments, H. salinarum displays uptake of iron but not of the chelator citrate. Uptake of iron was inhibited by cyanide and at higher concentrations by Ga. Furthermore, a K(M) for iron uptake in cells of 2.36 microM and a Vmax of approximately 67 pmol Fe/min/mg protein was determined. [55Fe]-uptake kinetics were measured in the absence and presence of Ga. Uptake of iron was inhibited merely at very high Ga concentrations. The results indicate an energy dependent iron uptake process in H. salinarum and suggest reduction of the metal at the membrane level.
Hubmacher
Dirk
D
Department of Anatomy and Cell Biology, McGill University of Montreal, 3640 University Street, Montreal, QC, Canada H3A 2B2.
Matzanke
Berthold F
BF
Anemüller
Stefan
S
D019843:Archaeal Proteins / Q000378:metabolism; D001692:Biological Transport; D019617:Halobacterium salinarum / Q000378:metabolism*; D007501:Iron / Q000737:chemistry / Q000378:metabolism*; D010084:Oxidation-Reduction; D017262:Siderophores / Q000378:metabolism
D019843:Archaeal Proteins; D017262:Siderophores; D007501:Iron