title: Agrobacterium tumefaciens membrane-bound ferritin plays a role in protection against hydrogen peroxide toxicity and is negatively regulated by the iron response regulator.
abstract: An Agrobacterium tumefaciens membrane-bound ferritin (mbfA) mutant was generated to assess the physiological functions of mbfA in response to iron and hydrogen peroxide (H(2) O(2) ) stresses. Wild-type and the mbfA mutant strains showed similar growth under high- and low-iron conditions. The mbfA mutant was more sensitive to H(2) O(2)  than wild-type strain. Expression of a functional mbfA gene could complement the H(2) O(2) -hypersensitive phenotype of the mbfA mutant and a rhizobial iron regulator (rirA) mutant, suggesting that MbfA protects cells from H(2) O(2)  toxicity by sequestering intracellular free iron, thus preventing the Fenton reaction. The expression of mbfA could be induced in response to iron and to H(2) O(2)  treatment. The iron response regulator (irr) also acted as a repressor of mbfA expression. An irr mutant had high constitutive expression of mbfA, which partly contributed to the H(2) O(2) -hyperresistant phenotype of the irr mutant. The data reported here demonstrate an important role of A. tumefaciens MbfA in the cellular defence against iron and H(2) O(2)  stresses.
authors.affiliation: Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand.
authors.forename: Nantaporn
authors.initials: N
authors.lastname: Ruangkiattikul
authors.forename: Sakkarin
authors.initials: S
authors.lastname: Bhubhanil
authors.forename: Jareeya
authors.initials: J
authors.lastname: Chamsing
authors.forename: Phettree
authors.initials: P
authors.lastname: Niamyim
authors.forename: Rojana
authors.initials: R
authors.lastname: Sukchawalit
authors.forename: Skorn
authors.initials: S
authors.lastname: Mongkolsuk
mesh_terms: D016960:Agrobacterium tumefaciens / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000378:metabolism*; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000633:toxicity*; D007501:Iron / Q000378:metabolism / Q000633:toxicity; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D014157:Transcription Factors; C114259:iron response regulator protein, Bacteria; D005293:Ferritins; D006861:Hydrogen Peroxide; D007501:Iron