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Overexpression of FurA in Anabaena sp. PCC 7120 Reveals New Targets for This Regulator Involved in Photosynthesis, Iron Uptake and Cellular Morphology

González, Andrés ; Bes, M. Teresa ; Barja, François ; Peleato, M. Luisa ; Fillat, María F.

In: Plant and Cell Physiology, 2010, vol. 51, no. 11, p. 1900-1914

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    Titre
    • Overexpression of FurA in Anabaena sp. PCC 7120 Reveals New Targets for This Regulator Involved in Photosynthesis, Iron Uptake and Cellular Morphology
    Auteur
    • González, Andrés. Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, 50009 Zaragoza, Spain
    • Bes, M. Teresa. Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, 50009 Zaragoza, Spain
    • Barja, François. Laboratory of Bioenergetics and Microbiology, University of Geneva, CH-1254 Jussy, Geneva, Switzerland
    • Peleato, M. Luisa. Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, 50009 Zaragoza, Spain
    • Fillat, María F.. Department of Biochemistry and Molecular and Cell Biology, and Biocomputation and Complex Systems Physics Institute (BiFi), University of Zaragoza, 50009 Zaragoza, Spain
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Plant and Cell Physiology, 2010, vol. 51, no. 11, p. 1900-1914. Oxford University Press
    Autre version électronique
    Identifiant OAI-PMH
    • oai:doc.rero.ch:290823
    Summary
    Previous genomic analyses of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 have identified three ferric uptake regulator (Fur) homologs with low sequence identities and probably different functions in the cell. FurA is a constitutive protein that shares the highest homology with Fur from heterotrophic bacteria and appears to be essential for invitro growth. In this study, we have analysed the effects of FurA overexpression on the Anabaena sp. phenotype and investigated which of the observed alterations were directly operated by FurA. Overexpression of the regulator led to changes in cellular morphology, resulting in shorter filaments with rounded cells of different sizes. The furA-overexpressing strain showed a slower photoautotrophic growth and a marked decrease in the oxygen evolution rate. Overexpression of the regulator also decreased both catalase and superoxide dismutase activities, but did not lead to an increase in the levels of intracellular reactive oxygen species. By combining phenotypic studies, reverse transcription-PCR analyses and electrophoretic mobility shift assays, we identified three novel direct targets of FurA, including genes encoding a siderophore outer membrane transporter (schT), bacterial actins (mreBCD) and the PSII reaction center protein D1 (psbA). The affinity of FurA for these novel targets was markedly affected by the absence of divalent metal ions, confirming previous evidence of a critical role for the metal co-repressor in the function of the regulator invivo. The results unravel new cellular processes modulated by FurA, supporting its role as a global transcriptional regulator in Anabaena sp. PCC 7120