Giardia intestinalis escapes oxidative stress by colonizing the small intestine: A molecular hypothesis

Authors

  • Daniela Mastronicola,

    1. Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
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    • Daniela Mastronicola and Alessandro Giuffrè contributed equally to this work.

  • Alessandro Giuffrè,

    1. Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
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    • Daniela Mastronicola and Alessandro Giuffrè contributed equally to this work.

  • Fabrizio Testa,

    1. Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
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  • Antonella Mura,

    1. Department of Biomedical Sciences, Division of Experimental and Clinical Microbiology, University of Sassari, Sassari, Italy
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  • Elena Forte,

    1. Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
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  • Eugenio Bordi,

    1. Clinical Chemistry and Microbiology Laboratory, Istituto Nazionale per le Malattie Infettive I.R.C.C.S. “Lazzaro Spallanzani,” Rome, Italy
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  • Leopoldo Paolo Pucillo,

    1. Clinical Chemistry and Microbiology Laboratory, Istituto Nazionale per le Malattie Infettive I.R.C.C.S. “Lazzaro Spallanzani,” Rome, Italy
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  • Pier Luigi Fiori,

    1. Department of Biomedical Sciences, Division of Experimental and Clinical Microbiology, University of Sassari, Sassari, Italy
    2. Center for Biotechnology Development and Biodiversity Research, University of Sassari, Sassari, Italy
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  • Paolo Sarti

    Corresponding author
    1. Department of Biochemical Sciences, CNR Institute of Molecular Biology and Pathology and Istituto Pasteur-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
    • Dipartimento di Scienze Biochimiche, Sapienza Università di Roma, Piazzale Aldo Moro 5, Roma I-00185, Italia
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    • Tel: +39-06-49910944. Fax: +39-06-4440062.


Abstract

Giardia intestinalis is the microaerophilic protozoon causing giardiasis, a common infectious intestinal disease. Giardia possesses an O2-scavenging activity likely essential for survival in the host. We report that Giardia trophozoites express the O2-detoxifying flavodiiron protein (FDP), detected by immunoblotting, and are able to reduce O2 to H2O rapidly (∼3 μM O2 × min × 106 cells at 37 °C) and with high affinity (C50 = 3.4 ± 0.7 μM O2). Following a short-term (minutes) exposure to H2O2 ≥ 100 μM, the O2 consumption by the parasites is irreversibly impaired, and the FDP undergoes a degradation, prevented by the proteasome-inhibitor MG132. Instead, H2O2 does not cause degradation or inactivation of the isolated FDP. On the basis of the elevated susceptibility of Giardia to oxidative stress, we hypothesize that the parasite preferentially colonizes the small intestine since, compared with colon, it is characterized by a greater capacity for redox buffering and a lower propensity to oxidative stress. © 2011 IUBMB IUBMB Life, 63(1): 21–25, 2011

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