Iron Storage inMycobacterium smegmatisGrown under Iron-sufficient and Iron-overload Conditions

Iron Acquisition and Metabolism by Mycobacteria

“…Siderophores are transient reservoirs of iron which bind to ferric iron during transport into the cell cytoplasm. Recent experimental evidence shows that very little intracellular iron is contained within these molecules on a long-term basis (31). In situ Mössbauer spectroscopy and electron paramagnetic resonance spectroscopy have been used to confirm these results, as signals associated with siderophore-bound iron are only observed upon short-term labeling of iron pools with 57 Fe (46,47).…”

Iron chelators from mycobacteria (1954–1999) and potential therapeutic applications

“…The presence of non-mycobactin-mediated ITMs led Ratledge to propose an iron storage role for mycobactins. 97,98 The recent evidence for and discovery of iron storage proteins such as bacterioferritin in three species of mycobacteria (M. leprae, 108,109 M. smegmatis, 110 and M. avium 111 ) may require a revision of this model. Furthermore, the previously mentioned Mössbauer and EPR studies on whole cells of M. smegmatis upon treatment with ferric citrate revealed a transient existence of the ferrimycobactin intermediate and the rise of spectroscopic signals consistent with the presence of bacterioferritin stored iron.…”

Iron Metabolism

“…For the movement of iron out of bacterioferritin, where it is stored as the crystalline ferric oxide/ hydroxide core (Chasteen 1998), it is supposed that this will be by a reductase or reductant but very little information is yet available on this subject. Ferredoxin, which has been proposed as a possible (cytosolic) storage molecule in M. smegmatis (Kikuchi et al 1994), may possibly play a role but this will probably be only in iron replete or iron overloaded cells.…”