Premium
Giardia intestinalis escapes oxidative stress by colonizing the small intestine: A molecular hypothesis
Author(s) -
Mastronicola Daniela,
Giuffrè Alessandro,
Testa Fabrizio,
Mura Antonella,
Forte Elena,
Bordi Eugenio,
Pucillo Leopoldo Paolo,
Fiori Pier Luigi,
Sarti Paolo
Publication year - 2011
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.409
Subject(s) - giardia , oxidative stress , mg132 , microbiology and biotechnology , biology , proteasome , parasite hosting , small intestine , oxidative phosphorylation , biochemistry , proteasome inhibitor , world wide web , computer science
Giardia intestinalis is the microaerophilic protozoon causing giardiasis, a common infectious intestinal disease. Giardia possesses an O 2 ‐scavenging activity likely essential for survival in the host. We report that Giardia trophozoites express the O 2 ‐detoxifying flavodiiron protein (FDP), detected by immunoblotting, and are able to reduce O 2 to H 2 O rapidly (∼3 μM O 2 × min × 10 6 cells at 37 °C) and with high affinity ( C 50 = 3.4 ± 0.7 μM O 2 ). Following a short‐term (minutes) exposure to H 2 O 2 ≥ 100 μM, the O 2 consumption by the parasites is irreversibly impaired, and the FDP undergoes a degradation, prevented by the proteasome‐inhibitor MG132. Instead, H 2 O 2 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