• BMB Reports
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• v.32 no.4
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• pp.405-408
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• 1999

The transactivation potential of HIV-1 Vpu was identified from the yeast two-hybrid screening process. The helix II domain of HIV-1 Vpu protein and mutant Vpu protein lacking the transmembrane domain exhibited transactivation of the LacZ and Leu2 reporter genes carrying LexA upstream activating sequences, but full-length HIV-1 Vpu and the helix I domain of HIV-1 Vpu did not. The helix II domain of HIV-1 Vpu consists of a number of acidic amino acids, and is especially rich in glutamic acid, a characteristic of many transcription factors. This result suggests that protein-protein interaction may occur through the acidic helix II domain of HIV-1 Vpu.

• Journal of Microbiology and Biotechnology
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• v.12 no.2
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• pp.286-291
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• 2002

Histone deacetylase I (HDAC1) works as one of the components in a nucleosome remodeling (NuRD) complex that consists of several proteins, including metastasis-associated protein 1 (MTA1). Since the protein-protein interaction of HDAC1 and MTA1 would appear to be important for both the integrity and functionality of the HDAC1 complex, the interruption of the HDAC1 and MTA1 interaction may be an efficient way to regulate the biological function of the HDAC1 complex. Based on this idea, a yeast two-hybrid system was constructed with HDAC1 and MTA1 expressing vectors in the DNA binding and activation domains, respectively. To verify the efficiency of the assay system, 3,500 microbial metabolite libraries were tested using the paper disc method, and KB0699 was found to inhibit the HDAC1 and MTA1 interaction without any toxicity to the wild-type yeast. Furthermore, KB0699 blocked the interaction of HDAC1 and MTA1 in an in vitro GST pull down assay and induced morphological changes in B16/BL6 melanoma cells, indicating the interruption of the HDAC1 complex function. Accordingly, these results demonstrated that the yeast assay strain developed in this study could be a valuable tool for the isolation of a HDAC1 complex disruptor.

• Proceedings of the Korean Society of Life Science Conference
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• 2005.04a
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• pp.23-36
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• 2005

Bax, a mammalian pro-apoptotic member of the Bcl-2 family, induces cell death when expressed In yeast. To investigate whether .Bax expression can induce cell death in plant, we produced transgenic Arabidopsis plants that contained murine Bax cDNA under control of a glucocorticoid-inducible promoter. Transgenic plants treated with dexamethasone, a strong synthetic glucocorticoid, induced Bax accumulation and cell death, suggesting that some elements of cell death mechanism by Bax may be conserved among various orgarusms. Therefore, we developed novel yeast genetic system, and cloned several Plant Bax Inhibitors (PBIs). Here, we report the function of two PBIs In detail. PBIl is ascorbate peroxidase (sAPX). Fluorescence method of dihydrorhodamine123 oxidation revealed that expression of Bax in yeast cells generated reactive oxygen species (ROS), and which was greatly reduced by co-expression with sAPX. These results suggest that sAPX inhibits the generation of ROS by Bax, which in turn suppresses Bax-induced cell death in yeast. PBI2 encodes nucleoside diphosphate kinase (NDPK). ROS stress strongly induces the expression of the NDPK2 gene in Arabidopsis thaliana (AtNDPK2). Transgenic plants overexpressing AtNDPK2 have lower lovels of ROS than wildtype plants. Mutants lacking AtNDPK2 had higher levels of ROS than wildtype. H$_{2O2}$ treatment induced the phosphorylation of two endogenous proteins whose molecular weights suggested they are AtMPK3 and AtMPK6. In the absence of H2O2 treatment, phosphorylation of these proteins was slightly elevated in plants overexpressing AtNDPK2 but markedly decreased In the AtNDPK2 deletion mutant. Yeast two-hybrid and in vitro protein pull-down assays revealed that AtNDPK2 specifically interacts with AtMPK3 and AtMPK6. Furthermore, AtNDPK2 also enhances the MBP phosphorylation activity of AtMPK3 i'n vitro. Finally, constitutive overexpression of AtNDPK2 in Arabidopsis plants conferred an enhanced tolerance to multiple environmental stresses that elicit ROS accumulation In situ. Thus, AtNDPK2 appears to play a novel regulatory role in H2O2-mediated MAPK signaling in plants.

• Journal of Life Science
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• v.27 no.6
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• pp.673-679
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• 2017

Microtubules are long rods in the cytoplasm of cells that plays a role in cell motility and intracellular transport. Microtubule-based transport by motor proteins is essential in intracellular transport. Kinesin 1 is a molecular motor protein that mediates the intracellular transport of various membranous vesicles, mRNAs, and proteins along microtubules. It is comprised of two heavy chains (KHCs, also called KIF5s) and two light chains (KLCs). KIF5s bear a motor domain in their amino (N)-terminal regions and interact with various cargoes through the cargo-binding domain in their carboxyl (C)-terminal regions. To identify proteins interacting with KIF5B, yeast two-hybrid screening was performed, and a specific interaction with the cytoplasmic linker protein 170 (CLIP-170), a plus end microtubule-binding protein, was found. The coiled-coil domain of CLIP-170 is essential for interactions with KIF5B in the yeast two-hybrid assay. CLIP-170 bound to the cargo-binding domain of KIF5B. Also, other KIF5s, KIF5A and KIF5C, interacted with CLIP-170 in the yeast two-hybrid assay. In addition, glutathione S-transferase (GST) pull-downs showed that KIF5s specifically interacted with CLIP-170. An antibody to KIF5B specifically co-immunoprecipitated CLIP-170 associated with KIF5B from mouse brain extracts. These results suggest that kinesin 1 motor protein may transport CLIP-170 in cells.

• The Plant Pathology Journal
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• v.31 no.2
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• pp.108-114
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• 2015

Curvularia lunata is an important maize foliar fungal pathogen that distributes widely in maize growing area in China, and several key pathogenic factors have been isolated. An yeast two-hybrid (Y2H) library is a very useful platform to further unravel novel pathogenic factors in C. lunata. To construct a high-quality full length-expression cDNA library from the C. lunata for application to pathogenesis-related protein-protein interaction screening, total RNA was extracted. The SMART (Switching Mechanism At 5' end of the RNA Transcript) technique was used for cDNA synthesis. Double-stranded cDNA was ligated into the pGADT7-Rec vector with Herring Testes Carrier DNA using homologous recombination method. The ligation mixture was transformed into competent yeast AH109 cells to construct the primary cDNA library. Eventually, a high qualitative library was successfully established according to an evaluation on quality. The transformation efficiency was about $6.39{\times}10^5$ transformants/$3{\mu}g$ pGADT7-Rec. The titer of the primary cDNA library was $2.5{\times}10^8cfu/mL$. The numbers for the cDNA library was $2.46{\times}10^5$. Randomly picked clones show that the recombination rate was 88.24%. Gel electrophoresis results indicated that the fragments ranged from 0.4 kb to 3.0 kb. Melanin synthesis protein Brn1 (1,3,8-hydroxynaphthalene reductase) was used as a "bait" to test the sufficiency of the Y2H library. As a result, a cDNA clone encoding VelB protein that was known to be involved in the regulation of diverse cellular processes, including control of secondary metabolism containing melanin and toxin production in many filamentous fungi was identified. Further study on the exact role of the VelB gene is underway.

• Molecules and Cells
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• v.26 no.3
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• pp.291-298
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• 2008

Human karyopherin ${\beta}3$, highly homologous to a yeast protein secretion enhancer (PSE1), has often been reported to be associated with a mediator of a nucleocytoplasmic transport pathway. Previously, we showed that karyopherin ${\beta}3$ complemented the PSE1 and KAP123 double mutant. Our research suggested that karyopherin beta has an evolutionary function similar to that of yeast PSE1 and/or KAP 123. In this study, we performed yeast two-hybrid screening to find a protein which would interact with karyopherin ${\beta}3$ and identified apolipoprotein A-I (apo A-I), a secretion protein with a primary function in cholesterol transport. By using in vitro binding assay, co-immunoprecipitation, and colocalization studies, we defined an interaction between karyopherin ${\beta}3$ and apo A-I. In addition, overexpression of karyopherin ${\beta}3$ significantly increased apo A-I secretion. These results suggest that karyopherin ${\beta}3$ plays a crucial role in apo A-I secretion. These findings may be relevant to the study of a novel function of karyopherin ${\beta}3$ and coronary artery diseases associated with apo A-I.

• Journal of Life Science
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• v.26 no.6
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• pp.698-704
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• 2016

The intracellular transport of organelles and protein complexes is mediated by kinesin superfamily proteins (KIFs). The first kinesin, kinesin 1, was identified as a molecular motor protein that moves various organelles and protein complexes along the microtubule rails in cells. Kinesin 1 is a tetramer of two heavy chains (KHCs, also called KIF5s) and two kinesin light chains (KLCs). KIF5s interact with many different proteins through their tail region, but their binding proteins have not yet been fully identified. To identify the interaction proteins for KIF5A, we performed yeast two-hybrid screening and found a specific interaction with ferritin heavy chain (Frt-h), which has a role in iron storage and detoxification. Frt-h bound to the amino acid residues between 800 and 940 of KIF5A and to other KIF5s in the yeast two-hybrid assay. The coiled-coil domain of Frt-h is essential for interaction with KIF5A. In addition, ferritin light chain (Frt-l) interacted with KIF5s in the yeast two-hybrid assay. In addition, these proteins showed specific interactions in the glutathione S-transferase (GST) pull-down assay. An antibody to KHC specifically co-immunoprecipitated Frt-h and Frt-l from mouse brain extracts. These results suggest the kinesin 1 motor protein may transport the ferritin complex in cells.

• Molecules and Cells
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• v.19 no.1
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• pp.39-45
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• 2005

RPK118 is a sphingosine kinase-1-binding protein that has been implicated in sphingosine 1 phosphate-mediated signaling. It contains a PX (phox homology) domain and two pseudo-kinase domains, and co-localizes with sphingosine kinase-1 on early endosomes. In this study we identified a novel RPK118-binding protein, PRDX3 (peroxiredoxin-3), by yeast two-hybrid screening. The interaction between these proteins was confirmed by pull-down assays and co-immunoprecipitation experiments. Deletion studies showed that RPK118 interacted with PRDX3 through its pseudokinase domains, and with early endosomes through its PX domain. Double immunofluorescence experiments demonstrated that PRDX3 co-localized with RPK118 on early endosomes in COS7 cells. PRDX3 is a member of the antioxidant family of proteins synthesized in the cytoplasm and functioning in mitochondria. Our findings indicate that RPK118 is a PRDX3-binding protein that may be involved in transporting PRDX3 from the cytoplasm to its mitochondrial site of function or to other membrane structures via endosome trafficking.

• Biomedical Science Letters
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• v.13 no.1
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• pp.1-10
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• 2007

Nebulin, a giant modular protein from muscle, is thought to act as molecular ruler in sarcomere assembly. In skeletal muscle, the C-terminal ${\sim}50 kDa$ region of nebulin extends into the Z-line lattice. The most recent studies implicated highlighting its extensive isoform diversity and exciting reports revealed its expression in cardiac and non-muscle tissues containing brain. Also these novel findings are indicating that nebulin is actually a multifunctional filament system, perhaps playing roles in signal transduction, contractile regulation, and myofibril force generation, as well as other not yet defined functions. However the binding protein of nebulin and function in brain is still unknown. A novel binding partner of nebulin C-terminal region was identified by screening a human brain cDNA library using yeast two-hybrid system. Nebulin C-terminus binding protein 51 (NCBP51) was contained a RING-finger domain and identified a new isoform of RING finger protein 125 (RNF125). The interaction was confirmed using the GST pull-down assay. NCBP51 belongs to a family of the RING finger proteins and its function remains to be identified in brain. The role of nebulin and NCBP51 will be studied by loss-of-function using siRNA technique in brain.

• Development and Reproduction
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• v.16 no.2
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• pp.129-135
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• 2012

Previously, we identified that the overexpression of IEX-1 induces apoptosis in ovarian cancer cells. Herein we report a new binding partner of IEX-1, CATHEPSIN B, as a lysosomal enzyme which contributes to the various apoptotic signaling in tumor cells. To investigate how IEX-1 regulates cellular survival and death event, we performed yeast two-hybrid screening of rat ovarian cDNA library using IEX-1 as the bait and found CATHEPSIN B. In the present study, CATHEPSIN B and IEX-1 proteins were overexpressed in 293T cells and their specific association was determined by immunoprecipitation and immunoblot analysis. In addition, the endogenous interaction between CATHEPSIN B and IEX-1 was confirmed in HeLa cells. The current finding of lysosomal CATHEPSIN B as the IEX-1-binding partner implies that IEX-1 may involve in lysosome-mediated apoptotic signaling pathways.