Characterization of a proteasome α-chain from Giardia lamblia

Emmerlich, Vera; Scholze, Henning; Gillin, Frances D.; Bakker-Grunwald, Tilly

doi:10.1007/s004360000332

Cited by 7 publications

(4 citation statements)

References 10 publications

(15 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Western blotting of protein extracts corresponding to these time points also indicated that there was no detectable change in the levels of the protein (Figure 6 b). This observation is consistent with the lack of change in the expression of the CP subunits during encystation [ 35 ]. Thus, based on analyses of the gene expression and protein levels in trophozoites and encysting trophozoites, it may be concluded that the decreased localization of GlRpn10 at the flagellar pore regions during encystation is likely to involve redistribution of the protein from these locations, rather than decreased gene expression or protein degradation.…”

Section: Resultssupporting

confidence: 89%

A reduced VWA domain-containing proteasomal ubiquitin receptor of Giardia lamblia localizes to the flagellar pore regions in microtubule-dependent manner

et al. 2015

View full text Add to dashboard Cite

BackgroundGiardia lamblia switches its lifecycle between trophozoite and cyst forms and the proteasome plays a pivotal role in this switching event. Compared to most model eukaryotes, the proteasome of this parasite has already been documented to have certain variations. This study was undertaken to characterize the ubiquitin receptor, GlRpn10, of the 19S regulatory particle of the Giardia proteasome and determine its cellular localization in trophozoites, encysting trophozoites and cysts.MethodSequence alignment and domain architecture analyses were performed to characterize GlRpn10. In vitro ubiquitin binding assay, functional complementation and biochemical studies verified the protein’s ability to function as ubiquitin receptor in the context of the yeast proteasome. Immunofluorescence localization was performed with antibody against GlRpn10 to determine its distribution in trophozoites, encysting trophozoites and cysts. Real-time PCR and Western blotting were performed to monitor the expression pattern of GlRpn10 during encystation.ResultGlRpn10 contained a functional ubiquitin interacting motif, which was capable of binding to ubiquitin. Although it contained a truncated VWA domain, it was still capable of partially complementing the function of the yeast Rpn10 orthologue. Apart from localizing to the nucleus and cytosol, GlRpn10 was also present at flagellar pores of trophozoites and this localization was microtubule-dependent. Although there was no change in the cellular levels of GlRpn10 during encystation, its selective distribution at the flagellar pores was absent.ConclusionGlRpn10 contains a noncanonical VWA domain that is partially functional in yeast. Besides the expected nuclear and cytosolic distribution, the protein displays microtubule-dependent flagellar pore localization in trophozoites. While the protein remained in the nucleus and cytosol in encysting trophozoites, it could no longer be detected at the flagellar pores. This absence at the flagellar pore regions in encysting trophozoites is likely to involve redistribution of the protein, rather than decreased gene expression or selective protein degradation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-0737-1) contains supplementary material, which is available to authorized users.

show abstract

Section: Resultssupporting

confidence: 89%

A reduced VWA domain-containing proteasomal ubiquitin receptor of Giardia lamblia localizes to the flagellar pore regions in microtubule-dependent manner

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Confocal microscopy analysis demonstrated that the giardial 20S core complex and 19S cap structure were associated with ESV membranes during early encystation until at least 7 h after induction. As noted previously, the expression of proteasome subunits is not upregulated in encysting cells [ 47 ]. The confocal microscopy data indicated a relocalization from more peripheral sites in the cytoplasm to the vicinity of ESVs, indicating a high rate of retrotranslocation of organelle proteins destined for degradation.…”

Section: The Role Of Proteasomes In Parasite Biology and Virulencesupporting

confidence: 52%

“…A study of the seven genes that encode the α subunits of the G. duodenalis proteasome indicated that the α -proteasome gene family evolved quickly from a single gene in the Archaea to seven or more genes in Eukarya [ 46 ]. The G. duodenalis 20S proteasome appears to be similar to that described in eukaryotic cells, containing a divergent set of α subunits [ 47 ]. Proteomics approaches performed to discover novel proteins associated with the stage-specific, Golgi-like encystation-specific vesicles (ESV) identified cytoplasmic and luminal factors of the endoplasmic reticulum quality-control system, that is, several structural ( α ) and catalytic ( β ) proteasome subunits.…”

Section: The Role Of Proteasomes In Parasite Biology and Virulencementioning

confidence: 99%

Role of the Ubiquitin-Proteasome Systems in the Biology and Virulence of Protozoan Parasites

Muñoz

Francisco

Gutiérrez

et al. 2015

BioMed Research International

View full text Add to dashboard Cite

In eukaryotic cells, proteasomes perform crucial roles in many cellular pathways by degrading proteins to enforce quality control and regulate many cellular processes such as cell cycle progression, signal transduction, cell death, immune responses, metabolism, protein-quality control, and development. The catalytic heart of these complexes, the 20S proteasome, is highly conserved in bacteria, yeast, and humans. However, until a few years ago, the role of proteasomes in parasite biology was completely unknown. Here, we summarize findings about the role of proteasomes in protozoan parasites biology and virulence. Several reports have confirmed the role of proteasomes in parasite biological processes such as cell differentiation, cell cycle, proliferation, and encystation. Proliferation and cell differentiation are key steps in host colonization. Considering the importance of proteasomes in both processes in many different parasites such as Trypanosoma, Leishmania, Toxoplasma, and Entamoeba, parasite proteasomes might serve as virulence factors. Several pieces of evidence strongly suggest that the ubiquitin-proteasome pathway is also a viable parasitic therapeutic target. Research in recent years has shown that the proteasome is a valid drug target for sleeping sickness and malaria. Then, proteasomes are a key organelle in parasite biology and virulence and appear to be an attractive new chemotherapeutic target.

show abstract

“…Thus it is not unlikely that this protein would be associated with S/MARs and have DNA binding properties. There have been reports on the proteasome 20 S of Giardia lamblia [47,48], where Emmerlich et al showed the 14 subunits making up this proteasome structure. Though the annotated genome of Giardia shows the presence of several of the proteasome 26 S subunits, no detailed analysis has been done on these proteins in Giardia .…”

Section: Discussionmentioning

confidence: 99%

Identification of scaffold/Matrix Attachment (S/MAR) like DNA element from the gastrointestinal protozoan parasite Giardia lamblia

Padmaja¹,

Jagannathan²,

Gupta³

et al. 2010

BMC Genomics

View full text Add to dashboard Cite

BackgroundChromatin in the nucleus of all eukaryotes is organized into a system of loops and domains. These loops remain fastened at their bases to the fundamental framework of the nucleus, the matrix or the scaffold. The DNA sequences which anchor the bases of the chromatin loops to the matrix are known as Scaffold/Matrix Attachment Regions or S/MARs. Though S/MARs have been studied in yeast and higher eukaryotes and they have been found to be associated with gene organization and regulation of gene expression, they have not been reported in protists like Giardia. Several tools have been discovered and formulated to predict S/MARs from a genome of a higher eukaryote which take into account a number of features. However, the lack of a definitive consensus sequence in S/MARs and the randomness of the protozoan genome in general, make it a challenge to predict and identify such sequences from protists.ResultsHere, we have analysed the Giardia genome for the probable S/MARs predicted by the available computational tools; and then shown these sequences to be physically associated with the nuclear matrix. Our study also reflects that while no single computational tool is competent to predict such complex elements from protist genomes, a combination of tools followed by experimental verification is the only way to confirm the presence of these elements from these organisms.ConclusionThis is the first report of S/MAR elements from the protozoan parasite Giardia lamblia. This initial work is expected to lay a framework for future studies relating to genome organization as well as gene regulatory elements in this parasite.

show abstract

Characterization of a proteasome α-chain from Giardia lamblia

Cited by 7 publications

References 10 publications

A reduced VWA domain-containing proteasomal ubiquitin receptor of Giardia lamblia localizes to the flagellar pore regions in microtubule-dependent manner

A reduced VWA domain-containing proteasomal ubiquitin receptor of Giardia lamblia localizes to the flagellar pore regions in microtubule-dependent manner

Role of the Ubiquitin-Proteasome Systems in the Biology and Virulence of Protozoan Parasites

Identification of scaffold/Matrix Attachment (S/MAR) like DNA element from the gastrointestinal protozoan parasite Giardia lamblia

Contact Info

Product

Resources

About