PMID:24600024

Citation	Bhubhanil, S, Chamsing, J, Sittipo, P, Chaoprasid, P, Sukchawalit, R and Mongkolsuk, S (2014) Roles of Agrobacterium tumefaciens membrane-bound ferritin (MbfA) in iron transport and resistance to iron under acidic conditions. Microbiology (Reading, Engl.) 160:863-71
Abstract	Agrobacterium tumefaciens membrane-bound ferritin (MbfA) is a member of the erythrin (Er)-vacuolar iron transport family. The MbfA protein has an Er or ferritin-like domain at its N terminus and has been predicted to have five transmembrane segments in its C-terminal region. Analysis of protein localization using PhoA and LacZ reporter proteins supported the view that the N-terminal di-iron site is located in the cytoplasm whilst the C-terminal end faces the periplasm. An A. tumefaciens mbfA mutant strain had 1.5-fold higher total iron content than the WT strain. Furthermore, multi-copy expression of mbfA reduced total iron content two- and threefold in WT and mbfA mutant backgrounds, respectively. These results suggest that MbfA may function as an iron exporter rather than an iron storage protein. The mbfA mutant showed 10-fold increased sensitivity to the iron-activated antibiotic streptonigrin, implying that the mutant had increased accumulation of intracellular free iron. Growth of the mbfA mutant was reduced in the presence of high iron under acidic conditions. The expression of mbfA was induced highly in cells grown in iron-replete medium at pH 5.5, further supporting the view that mbfA is involved in the response to iron under acidic conditions. A. tumefaciens MbfA may play a protective role against increased free iron in the cytoplasm through iron binding and export, thus preventing iron-induced toxicity via the Fenton reaction.
Links	PubMed Online version:10.1099/mic.0.076802-0
Keywords	Agrobacterium tumefaciens/drug effects; Agrobacterium tumefaciens/genetics; Agrobacterium tumefaciens/growth & development; Agrobacterium tumefaciens/metabolism; Cell Membrane/metabolism; Drug Resistance, Bacterial; Ferritins/genetics; Ferritins/metabolism; Gene Deletion; Hydrogen-Ion Concentration; Iron/metabolism; Iron/toxicity; Membrane Transport Proteins/genetics; Membrane Transport Proteins/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AGRFC:Q7CWA3		GO:0006879: cellular iron ion homeostasis	ECO:0000315:		P		Figure 2 shows that mbfA mutant has higher levels of total iron content than WT(specifically part a of the figure)	complete

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