Ubiquitination dynamics in the early-branching eukaryote Giardia intestinalis
Article first published online: 23 APR 2013
© 2013 The Authors. Microbiology Open published by John Wiley & Sons Ltd.
This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Volume 2, Issue 3, pages 525–539, June 2013
How to Cite
MicrobiologyOpen 2013; 2(3): 525–439
- Issue published online: 7 JUN 2013
- Article first published online: 23 APR 2013
- Manuscript Accepted: 12 MAR 2013
- Manuscript Revised: 11 MAR 2013
- Manuscript Received: 12 DEC 2012
- Universidad Nacional de Colombia research division. Grant Numbers: 8003322, 8003244
- Associazione Italiana per la Ricerca sul Cancro
- EMBO Young Investigator Program
- European Community. Grant Numbers: 100601, 201012
- Universidad Nacional de Colombia
- Giardia ;
Ubiquitination is a highly dynamic and versatile posttranslational modification that regulates protein function, stability, and interactions. To investigate the roles of ubiquitination in a primitive eukaryotic lineage, we utilized the early-branching eukaryote Giardia intestinalis. Using a combination of biochemical, immunofluorescence-based, and proteomics approaches, we assessed the ubiquitination status during the process of differentiation in Giardia. We observed that different types of ubiquitin modifications present specific cellular and temporal distribution throughout the Giardia life cycle from trophozoites to cyst maturation. Ubiquitin signal was detected in the wall of mature cysts, and enzymes implicated in cyst wall biogenesis were identified as substrates for ubiquitination. Interestingly, inhibition of proteasome activity did not affect trophozoite replication and differentiation, while it caused a decrease in cyst viability, arguing for proteasome involvement in cyst wall maturation. Using a proteomics approach, we identified around 200 high-confidence ubiquitinated candidates that vary their ubiquitination status during differentiation. Our results indicate that ubiquitination is critical for several cellular processes in this primitive eukaryote.