Isolation and subunit composition of the 20S proteasome of Giardia lamblia

Emmerlich, Vera; Santarius, Ute; Bakker-Grunwald, Tilly; Scholze, Henning

doi:10.1016/s0166-6851(99)00022-5

Cited by 18 publications

(15 citation statements)

References 18 publications

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“…Such activity was increased with the addition of exogenous ubiquitin, an ATP-regenerating system and a deubiquitinating enzyme inhibitor. Our results support those of Emmerlich et al (1999). They also confirm the active presence of a ubiquitin/proteasome system as a pathway for selective and specific protein degradation in G. intestinalis.…”

Section: Discussionsupporting

confidence: 89%

Identification and expression of the protein ubiquitination system in Giardia intestinalis

2007

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Giardia intestinalis is a single-cell eukaryotic microorganism, regarded as one of the earliest divergent eukaryotes and thus an attractive model to study the evolution of regulatory systems. Giardia has two different forms throughout its life cycle, cyst and trophozoite, and changes from one to the other in response to environmental signals. The two differentiation processes involve a differential gene expression as well as a quick and specific protein turnover that may be mediated by the ubiquitin/proteasome system. The aim of this work was to search for unreported components of the ubiquitination system and to experimentally demonstrate their expression in the parasite and during the two differentiation processes. We found activity of protein ubiquitination in G. intestinalis trophozoites and analyzed the transcription of the ubiquitin gene, as well as that of the activating (E1), conjugating (E2), and ligase (E3) ubiquitin enzymes during encystation and excystation. A constant ubiquitin expression persisted during the parasite's differentiation processes, whereas variation in transcription was observed in the other genes under study.

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Section: Discussionsupporting

confidence: 89%

Identification and expression of the protein ubiquitination system in Giardia intestinalis

2007

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“…Even so, G. lamblia is so far unique in that it has only a single monoubiquitin gene (Krebber et al 1994), and we interpret this to be an original rather than a regressed feature. However, judging from the pattern of protein spots on a 2D gel, the 20S proteasome of G. lamblia seems to have a complexity similar to that of other eukaryotes (Emmerlich et al 1999). As a further step in the characterization of the G. lamblia proteasome, we now report the sequence and expression of one of its noncatalytic subunits, a3.…”

Section: Introductionmentioning

confidence: 91%

“…Eurogentec). Puri®cation of the 20S proteasome of G. lamblia, SDS-PAGE and 2D-PAGE were as described by Emmerlich et al (1999). Western analysis was performed with 20 lg antigen per lane.…”

Section: Screening Of a Genomic Librarymentioning

confidence: 99%

Characterization of a proteasome α-chain from Giardia lamblia

Emmerlich

Scholze

Gillin

et al. 2001

Parasitology Research

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To begin to characterize the components of the 20S proteasome of Giardia lamblia, we have cloned a genomic sequence encoding an alpha-chain (type alpha3/C9, predicted size 244 amino acid residues). Southern analysis indicated that a single gene codes for this protein, and a Northern blot exhibited a single signal at 850 nt. An antiserum against a C-terminal fragment of the alpha-chain expressed in Escherichia coli reacted with a single protein band of Mr 27,000 that was present at constant levels in trophozoites and encysting cells. On a 2D blot of the purified 20S proteasome, we identified the cross-reacting component as a single protein of IEP 6.0, in agreement with the IEP predicted by the coding sequence. Our data confirm that the G. lamblia 20S proteasome is typically eukaryotic in containing a set of diverged alpha-subunits.

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“…Archaea have the simplest proteasome, consisting of two alpha and two beta heptamers, while the eukaryotic 20S proteasome contains seven different alpha and seven different beta subunits organized in a manner similar to the Archaea. Since G. lamblia has certain similarities to the Archaea but other eukaryotic features, it is of interest that the 20S proteasome of Giardia demonstrates a distinctly eukaryotic pattern with 14 subunits (77). Proteins are targeted to the proteasomes by ubiquitin, which appears to be present in Giardia as a single-copy gene, in contrast to the multiple gene copies found in other eukaryotes (168).…”

Section: Protein Transport and Degradationmentioning

confidence: 99%

Biology ofGiardia lamblia

2001

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Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5′ and 3′ untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism

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Isolation and subunit composition of the 20S proteasome of Giardia lamblia

Cited by 18 publications

References 18 publications

Identification and expression of the protein ubiquitination system in Giardia intestinalis

Identification and expression of the protein ubiquitination system in Giardia intestinalis

Characterization of a proteasome α-chain from Giardia lamblia

Biology ofGiardia lamblia

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