Interaction of β-Giardin with the Bop1 Protein in Giardia lamblia

Kim, J.; Goo, Sung Young; Chung, Hyun Kee; Yang, Hea-Eun; Yong, Tai Soon; Lee, K. H.; Park, Soon‐Jung

doi:10.1007/s00436-005-0040-8

Cited by 6 publications

(8 citation statements)

References 15 publications

(16 reference statements)

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“…In addition, the role of GlEB1 was assessed by complementation assays using a BIM1 mutant of Saccharomyces cerevisiae , in which proper positioning of the nucleus is abolished [13]. Through co-immunoprecipitation and yeast two-hybrid assays, block of proliferation 1 and cytoskeletal proteins such as β- and γ-giardins, were identified as EB1-interacting proteins [14], [15], [16]. However, it remains to be elucidated how GlEB1 modulates MT dynamics during the cell cycle of G. lamblia .…”

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confidence: 99%

Characterization of Microtubule-Binding and Dimerization Activity of Giardia lamblia End-Binding 1 Protein

et al. 2014

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End-binding 1 (EB1) proteins are evolutionarily conserved components of microtubule (MT) plus-end tracking protein that regulate MT dynamics. Giardia lamblia, with two nuclei and cytoskeletal structures, requires accurate MT distribution for division. In this study, we show that a single EB1 homolog gene of G. lamblia regulates MT dynamics in mitosis. The haemagglutinin-tagged G. lamblia EB1 (GlEB1) localizes to the nuclear envelopes and median bodies, and is transiently present in mitotic spindles of dividing cells. Knockdown of GlEB1 expression using the morpholinos-based anti-EB1 oligonucleotides, resulted in a significant defect in mitosis of Giardia trophozoites. The MT-binding assays using recombinant GlEB1 (rGlEB1) proteins demonstrated that rGlEB1102–238, but not rGlEB11–184, maintains an MT-binding ability comparable with that of the full length protein, rGlEB11–238. Size exclusion chromatography showed that rGlEB1 is present as a dimer formed by its C-terminal domain and a disulfide bond. In vitro-mutagenesis of GlEB1 indicated that an intermolecular disulfide bond is made between cysteine #13 of the two monomers. Complementation assay using the BIM1 knockout mutant yeast, the yeast homolog of mammalian EB1, indicated that expression of the C13S mutant GlEB1 protein cannot rescue the mitotic defect of the BIM1 mutant yeast. These results suggest that dimerization of GlEB1 via the 13th cysteine residues plays a role during mitosis in Giardia.

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Section: Introductionmentioning

confidence: 99%

Characterization of Microtubule-Binding and Dimerization Activity of Giardia lamblia End-Binding 1 Protein

et al. 2014

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“…A G. lamblia cDNA encoding a putative block of proliferation 1 (Bop1) protein was found to interact with β-giardin, a Giardia-specific cytoskeletal protein (Kim et al 2006). Yeast two-hybrid screening of a G. lamblia cDNA library with Bop1 as bait led to the isolation of endbinding (EB1) protein 1, a protein that is known to function as a microtubule (MT) plus-end-tracking protein in other organisms, suggesting a coordination between ribosome biogenesis and cell cycle-related processes such as mitosis (Kim et al 2008a).…”

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confidence: 99%

Identification of end-binding 1 (EB1) interacting proteins in Giardia lamblia

et al. 2009

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Yeast two-hybrid assays using the end-binding 1 (EB1) protein of Giardia lamblia as bait led to the isolation of four independent clones encoding gamma-giardin, a neurogenic Notch-like protein, and two hypothetical proteins. Interactions between EB1 and the isolated proteins were confirmed by co-immunoprecipitation of in vitro-synthesized candidate proteins and EB1. Localization of these isolated proteins in G. lamblia was examined by immunofluorescence assays, indicating that they were predominantly present in cytoskeletal structures of G. lamblia. These results suggest that EB1 protein functions via interaction with the cytoskeletal components of G. lamblia.

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“…; Kim et al. , ), have been shown to interact with GlEB1 through co‐immunoprecipitation and yeast two‐hybrid assays. However, few studies have examined the mechanism through which EB1 is regulated or the specific target components modulated by EB1 in G. lamblia .…”

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Phosphorylation of Serine 148 in Giardia lamblia End‐binding 1 Protein is Important for Cell Division

Kim

Lee

et al. 2016

J Eukaryotic Microbiology

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Giardia lamblia is a unicellular organism, showing a polarity with two nuclei and cytoskeletal structures. Accurate positioning of these organelles is essential for division of G. lamblia, which is poorly understood. Giardia lamblia end-binding 1 (GlEB1) protein and G. lamblia aurora kinase (GlAK) have been shown to modulate microtubule (MT) distribution during cytokinesis. A direct association between GlEB1 and GlAK was demonstrated. Like GlEB1, GlAK was also found at nuclear envelopes and median bodies of G. lamblia. In vitro kinase assays using Giardia lysates immunoprecipitated with anti-GlAK antibodies or recombinant GlAK suggested that GlEB1 is a substrate of GlAK. Site-directed mutagenesis indicated that threonine-205 in GlAK was auto-phosphorylated and that GlAK phosphorylated serine (Ser)-148 in GlEB1. Ectopic expression of a mutant GlEB1 (with conversion of Ser-148 into alanine of GlEB1) resulted in an increased number of Giardia cells with division defects. Treatment of G. lamblia with an AK inhibitor triggered cytokinesis defects, and ectopic expression of a phospho-mimetic mutant GlEB1 (with conversion of Ser-148 into aspartate) rescued the defects in Giardia cell division caused by the AK inhibitor. These results suggested that phosphorylation of GlEB1 played a role in cytokinesis in G. lamblia.

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Interaction of β-Giardin with the Bop1 Protein in Giardia lamblia

Cited by 6 publications

References 15 publications

Characterization of Microtubule-Binding and Dimerization Activity of Giardia lamblia End-Binding 1 Protein

Characterization of Microtubule-Binding and Dimerization Activity of Giardia lamblia End-Binding 1 Protein

Identification of end-binding 1 (EB1) interacting proteins in Giardia lamblia

Phosphorylation of Serine 148 in Giardia lamblia End‐binding 1 Protein is Important for Cell Division

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