Role and regulation of ferritin-like proteins in iron homeostasis and oxidative stress survival of Caulobacter crescentus

Autor(es)

de Castro Ferreira, Ivan Goncalves ; Rodrigues, Mirian Molnar ; da Silva Neto, Jose Freire ; Mazzon, Ricardo Ruiz ; Marques, Marilis do Valle

• Tipo de documento: Artigo Científico
• Fonte: BIOMETALS; v. 29, n. 5, p. 851-862, OCT 2016.
• Citações Web of Science: 3

Resumo

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. (AU)

• Processo FAPESP: 09/02379-1 - Estudo do papel de duas ferritinas no metabolismo de ferro de Caulobacter crescentus e sua regulação por um pequeno RNA
• Beneficiário: Mirian Molnar Rodrigues
• Modalidade de apoio: Bolsas no Brasil - Mestrado