Identification and expression of the protein ubiquitination system in Giardia intestinalis

Gallego, Eva; Alvarado, Magda E.; Wasserman, Moisés

doi:10.1007/s00436-007-0458-2

Cited by 30 publications

(22 citation statements)

References 26 publications

(25 reference statements)

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“…The gene encoding for ubiquitin carboxy-terminal hydrolase (EIN_243050) with a peptidase C19 motif was up-regulated at 8 to 120 h with a 67-fold peak expression at 24 h. A gene encoding for Ub-specific protease (EIN_107760) was also up-regulated at 24 to 48 h of encystation (Table S3). These de-ubiquitinating enzymes are likely required to process Ub-conjugated products, negatively regulate ubiquitination, and regenerate free Ub [49]. …”

Section: Resultsmentioning

confidence: 99%

Transcriptome Analysis of Encystation in Entamoeba invadens

et al. 2013

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Encystation is an essential differentiation process for the completion of the life cycle of a group of intestinal protozoa including Entamoeba histolytica, the causative agent of intestinal and extraintestinal amebiasis. However, regulation of gene expression during encystation is poorly understood. To comprehensively understand the process at the molecular level, the transcriptomic profiles of E . invadens , which is a related reptilian species that causes an invasive disease similar to that of E. histolytica, was investigated during encystation. Using a custom-generated Affymetrix platform microarray, we performed time course (0.5, 2, 8, 24, 48, and 120 h) gene expression analysis of encysting E . invadens . ANOVA analysis revealed that a total of 1,528 genes showed ≥3 fold up-regulation at one or more time points, relative to the trophozoite stage. Of these modulated genes, 8% (116 genes) were up-regulated at the early time points (0.5, 2 and 8h), while 63% (962 genes) were up-regulated at the later time points (24, 48, and 120 h). Twenty nine percent (450 genes) are either up-regulated at 2 to 5 time points or constitutively up-regulated in both early and late stages. Among the up-regulated genes are the genes encoding transporters, cytoskeletal proteins, proteins involved in vesicular trafficking (small GTPases), Myb transcription factors, cysteine proteases, components of the proteasome, and enzymes for chitin biosynthesis. This study represents the first kinetic analysis of gene expression during differentiation from the invasive trophozoite to the dormant, infective cyst stage in Entamoeba . Functional analysis on individual genes and their encoded products that are modulated during encystation may lead to the discovery of targets for the development of new chemotherapeutics that interfere with stage conversion of the parasite.

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Section: Resultsmentioning

confidence: 99%

Transcriptome Analysis of Encystation in Entamoeba invadens

et al. 2013

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“…Although Giardia has a proteasome (Paugam et al, 2003), and an active ubiquitin conjugation system (Gallego et al, 2007), Giardia cyclin B is not regulated by ubiquitin-mediated degradation in contrast to all mitotic cyclins characterized to date. Though Sacchoromyces cerevisiae strains have been engineered to complete anaphase and progress to telophase in the absence of an APC (Thornton and Toczyski, 2003) this is the first example of a eukaryotic organism that naturally progresses through the cell cycle without an APC.…”

Section: Introductionmentioning

confidence: 99%

The Giardia cell cycle progresses independently of the Anaphase Promoting Complex

Gourguechon

Holt

Cande

2013

Journal of Cell Science

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SummaryMost cell cycle regulation research has been conducted in model organisms representing a very small part of the eukaryotic domain. The highly divergent human pathogen Giardia intestinalis is ideal for studying the conservation of eukaryotic pathways. Although Giardia has many cell cycle regulatory components, its genome lacks all anaphase-promoting complex (APC) components. In the present study, we show that a single mitotic cyclin in Giardia is essential for progression into mitosis. Strikingly, Giardia cyclin B lacks the conserved N-terminal motif required for timely degradation mediated by the APC and ubiquitin conjugation. Expression of Giardia cyclin B in fission yeast is toxic, leading to a prophase arrest, and this toxicity is suppressed by the addition of a fission yeast degradation motif. Cyclin B is degraded during mitosis in Giardia cells, but this degradation appears to be independent of the ubiquitination pathway. Other putative APC substrates, aurora and polo-like kinases, also show no evidence of ubiquitination. This is the first example of mitosis not regulated by the APC and might reflect an evolutionary ancient form of cell cycle regulation.

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“…By searching the GiardiaDB, we identified a SUMO gene with products that are highly homologous to SUMO-1 isoforms and SMT3C of yeast, a gene that encodes for a putative gSP, and two proteins, putative gSAE2 and putative Ubc9, with high identity and homology to the SUMOylation enzymes, presumed to function in both the SUMOylation and the ubiquitination pathways [5,8,52]. The over-expression of SUMO in Giardia and in the mAbs produced, enabled us to describe the localization of SUMO in wild-type and transgenic trophozoites and the presence of potential SUMO conjugates.…”

Section: Discussionmentioning

confidence: 99%

SUMOylation in Giardia lamblia: A Conserved Post-Translational Modification in One of the Earliest Divergent Eukaryotes

et al. 2012

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Post-translational modifications are able to regulate protein function and cellular processes in a rapid and reversible way. SUMOylation, the post-translational modification of proteins by the addition of SUMO, is a highly conserved process that seems to be present in modern cells. However, the mechanism of protein SUMOylation in earlier divergent eukaryotes, such as Giardia lamblia , is only starting to become apparent. In this work, we report the presence of a single SUMO gene encoding to SUMO protein in Giardia . Monoclonal antibodies against recombinant Giardia SUMO protein revealed the cytoplasmic localization of native SUMO in wild-type trophozoites. Moreover, the over-expression of SUMO protein showed a mainly cytoplasmic localization, though also neighboring the plasma membrane, flagella, and around and even inside the nuclei. Western blot assays revealed a number of SUMOylated proteins in a range between 20 and 120 kDa. The genes corresponding to putative enzymes involved in the SUMOylation pathway were also explored. Our results as a whole suggest that SUMOylation is a process conserved in the eukaryotic lineage, and that its study is significant for understanding the biology of this interesting parasite and the role of post-translational modification in its evolution.

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Identification and expression of the protein ubiquitination system in Giardia intestinalis

Cited by 30 publications

References 26 publications

Transcriptome Analysis of Encystation in Entamoeba invadens

Transcriptome Analysis of Encystation in Entamoeba invadens

The Giardia cell cycle progresses independently of the Anaphase Promoting Complex

SUMOylation in Giardia lamblia: A Conserved Post-Translational Modification in One of the Earliest Divergent Eukaryotes

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