title: Role and regulation of ferritin-like proteins in iron homeostasis and oxidative stress survival of Caulobacter crescentus.
abstract: Iron is an essential nutrient that is poorly available to living organisms but can be harmful when in excess due to the production of reactive oxygen species. Bacteria and other organisms use iron storage proteins called ferritins to avoid iron toxicity and as a safe iron source in the cytosol. The alpha-proteobacterium Caulobacter crescentus has two putative ferritins, Bfr and Dps, and some other proteins belonging to the ferritin-like superfamily, among them the one encoded by CC_0557. In this work, we have analyzed the role and regulation of these three putative ferritin-like proteins. Using lacZ-transcriptional fusions, we found that bfr expression is positively regulated (2.5-fold induction) by the Fe-responsive regulator Fur in iron sufficiency, as expected for an iron storage protein. Expression of dps was induced 1.5-fold in iron limitation in a Fur-independent manner, while the expression of the product of CC_0557 was unaffected by either iron supply or Fur. With respect to growth phase, while bfr expression was constant during growth, expression of dps (1.4-fold) and CC_0557 (around seven times) increased in the transition from exponential to stationary phase. Deletion mutant strains for each gene and a double dps/bfr mutant were obtained and tested for oxidative stress resistance. The dps mutant was very sensitive to H2O2, and this phenotype was not relieved by the addition of the iron chelator 2',2-dipyridyl in the conditions tested. While bfr and CC_0557 showed no phenotype as to H2O2 resistance, the double dps/bfr mutant had a similar phenotype to the dps mutation alone. These findings indicate that in C. crescentus Bfr contributes to iron homeostasis and Dps has a role in protection against oxidative stress. The role of the protein CC_0557 containing a ferritin-like fold remains unclear.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil.
authors.forename: Ivan Gonçalves
authors.initials: IG
authors.lastname: de Castro Ferreira
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil.
authors.forename: Mirian Molnar
authors.initials: MM
authors.lastname: Rodrigues
authors.affiliation: Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, SP, 14049-900, Brazil.
authors.forename: José Freire
authors.initials: JF
authors.lastname: da Silva Neto
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, PO box 476, Campus Universitário da Trindade, Florianópolis, SC, 88040-900, Brazil.
authors.forename: Ricardo Ruiz
authors.initials: RR
authors.lastname: Mazzon
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, São Paulo, SP, 05508-900, Brazil. mvmarque@usp.br.|, Lineu Prestes, 1374, São Paulo, SP, 05508-900, Brazil. mvmarque@usp.br.
authors.forename: Marilis
authors.initials: M
authors.lastname: do Valle Marques
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D016935:Caulobacter crescentus / Q000254:growth & development / Q000378:metabolism*; D005293:Ferritins / Q000378:metabolism*; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D018384:Oxidative Stress
chemical_list: D001426:Bacterial Proteins; D005293:Ferritins; D007501:Iron
keywords: Caulobacter crescentus; Ferritin; Iron homeostasis; Oxidative stress