Ubiquitination dynamics in the early-branching eukaryote Giardia intestinalis

Authors

  • Carlos A. Niño,

    1. Laboratorio de Investigaciones Básicas en Bioquímica – LIBBIQ, Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
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  • Jenny Chaparro,

    1. Laboratorio de Investigaciones Básicas en Bioquímica – LIBBIQ, Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
    2. Facultad de Ciencias Agrarias, Universidad de Antioquia, Medellín, Colombia
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  • Paolo Soffientini,

    1. IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
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  • Simona Polo,

    Corresponding author
    1. IFOM, Fondazione Istituto FIRC di Oncologia Molecolare, Milan, Italy
    2. Dipartimento di Scienze della Salute, Universita' degli Studi di Milano, Milan, Italy
    • Laboratorio de Investigaciones Básicas en Bioquímica – LIBBIQ, Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
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  • Moises Wasserman

    Corresponding author
    • Laboratorio de Investigaciones Básicas en Bioquímica – LIBBIQ, Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
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Correspondence

Moises Wasserman, Universidad Nacional de Colombia, Unidad Camilo Torres, Calle 44 No 45-67, Bloque 10, Nivel 4, Bogotá, Colombia.

Tel/Fax: 57 1 3165000 Ext. 10617;

E-mail: mwassermannl@unal.edu.co

Simona Polo, IFOM, Via Adamello 16, 20139, Milan, Italy.

Tel: +39 02 574303242;

Fax: +39 02 574303231;

E-mail: simona.polo@ifom.eu

Abstract

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.

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