scholarly journals Defining desmosomal plakophilin-3 interactions

2003 ◽  
Vol 161 (2) ◽  
pp. 403-416 ◽  
Author(s):  
Stefan Bonné ◽  
Barbara Gilbert ◽  
Mechthild Hatzfeld ◽  
Xinyu Chen ◽  
Kathleen J. Green ◽  
...  

Plakophilin 3 (PKP3) is a recently described armadillo protein of the desmosomal plaque, which is synthesized in simple and stratified epithelia. We investigated the localization pattern of endogenous and exogenous PKP3 and fragments thereof. The desmosomal binding properties of PKP3 were determined using yeast two-hybrid, coimmunoprecipitation and colocalization experiments. To this end, novel mouse anti-PKP3 mAbs were generated. We found that PKP3 binds all three desmogleins, desmocollin (Dsc) 3a and -3b, and possibly also Dsc1a and -2a. As such, this is the first protein interaction ever observed with a Dsc-b isoform. Moreover, we determined that PKP3 interacts with plakoglobin, desmoplakin (DP) and the epithelial keratin 18. Evidence was found for the presence of at least two DP–PKP3 interaction sites. This finding might explain how lateral DP–PKP interactions are established in the upper layers of stratified epithelia, increasing the size of the desmosome and the number of anchoring points available for keratins. Together, these results show that PKP3, whose epithelial and epidermal desmosomal expression pattern and protein interaction repertoire are broader than those of PKP1 and -2, is a unique multiprotein binding element in the basic architecture of a vast majority of epithelial desmosomes.

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
M. V. Borca ◽  
E. A. Vuono ◽  
E. Ramirez-Medina ◽  
P. Azzinaro ◽  
K. A. Berggren ◽  
...  

ABSTRACT The E2 protein in classical swine fever (CSF) virus (CSFV) is the major virus structural glycoprotein and is an essential component of the viral particle. E2 has been shown to be involved in several functions, including virus adsorption, induction of protective immunity, and virulence in swine. Using the yeast two-hybrid system, we previously identified a swine host protein, dynactin subunit 6 (DCTN6) (a component of the cell dynactin complex), as a specific binding partner for E2. We confirmed the interaction between DCTN6 and E2 proteins in CSFV-infected swine cells by using two additional independent methodologies, i.e., coimmunoprecipitation and proximity ligation assays. E2 residues critical for mediating the protein-protein interaction with DCTN6 were mapped by a reverse yeast two-hybrid approach using a randomly mutated E2 library. A recombinant CSFV mutant, E2ΔDCTN6v, harboring specific substitutions in those critical residues was developed to assess the importance of the E2-DCTN6 protein-protein interaction for virus replication and virulence in swine. CSFV E2ΔDCTN6v showed reduced replication, compared with the parental virus, in an established swine cell line (SK6) and in primary swine macrophage cultures. Remarkably, animals infected with CSFV E2ΔDCTN6v remained clinically normal during the 21-day observation period, which suggests that the ability of CSFV E2 to bind host DCTN6 protein efficiently during infection may play a role in viral virulence. IMPORTANCE Structural glycoprotein E2 is an important component of CSFV due to its involvement in many virus activities, particularly virus-host interactions. Here, we present the description and characterization of the protein-protein interaction between E2 and the swine host protein DCTN6 during virus infection. The E2 amino acid residues mediating the interaction with DCTN6 were also identified. A recombinant CSFV harboring mutations disrupting the E2-DCTN6 interaction was created. The effect of disrupting the E2-DCTN6 protein-protein interaction was studied using reverse genetics. It was shown that the same amino acid substitutions that abrogated the E2-DCTN6 interaction in vitro constituted a critical factor in viral virulence in the natural host, domestic swine. This highlights the potential importance of the E2-DCTN6 protein-protein interaction in CSFV virulence and provides possible mechanisms of virus attenuation for the development of improved CSF vaccines.


2007 ◽  
Vol 4 (5) ◽  
pp. 405-407 ◽  
Author(s):  
Fulai Jin ◽  
Larisa Avramova ◽  
Jing Huang ◽  
Tony Hazbun

2010 ◽  
Vol 9 (9) ◽  
pp. 1392-1396
Author(s):  
Zhu Tingheng ◽  
Wang Weixia ◽  
Wong Hann lin ◽  
Yang Xiao ◽  
Wang Kun ◽  
...  

2000 ◽  
Vol 149 (7) ◽  
pp. 1419-1432 ◽  
Author(s):  
Ute Schaeper ◽  
Niels H. Gehring ◽  
Klaus P. Fuchs ◽  
Martin Sachs ◽  
Bettina Kempkes ◽  
...  

Gab1 is a substrate of the receptor tyrosine kinase c-Met and involved in c-Met–specific branching morphogenesis. It associates directly with c-Met via the c-Met–binding domain, which is not related to known phosphotyrosine-binding domains. In addition, Gab1 is engaged in a constitutive complex with the adaptor protein Grb2. We have now mapped the c-Met and Grb2 interaction sites using reverse yeast two-hybrid technology. The c-Met–binding site is localized to a 13–amino acid region unique to Gab1. Insertion of this site into the Gab1-related protein p97/Gab2 was sufficient to confer c-Met–binding activity. Association with Grb2 was mapped to two sites: a classical SH3-binding site (PXXP) and a novel Grb2 SH3 consensus-binding motif (PX(V/I)(D/N)RXXKP). To detect phosphorylation-dependent interactions of Gab1 with downstream substrates, we developed a modified yeast two-hybrid assay and identified PI(3)K, Shc, Shp2, and CRKL as interaction partners of Gab1. In a trk-met-Gab1–specific branching morphogenesis assay, association of Gab1 with Shp2, but not PI(3)K, CRKL, or Shc was essential to induce a biological response in MDCK cells. Overexpression of a Gab1 mutant deficient in Shp2 interaction could also block HGF/SF-induced activation of the MAPK pathway, suggesting that Shp2 is critical for c-Met/Gab1-specific signaling.


2000 ◽  
Vol 350 (3) ◽  
pp. 741-746 ◽  
Author(s):  
Julian GRUSOVIN ◽  
Violet STOICHEVSKA ◽  
Keith H. GOUGH ◽  
Katrina NUNAN ◽  
Colin W. WARD ◽  
...  

munc18c is a critical protein involved in trafficking events associated with syntaxin 4 and which also mediates inhibitory effects on vesicle docking and/or fusion. To investigate the domains of munc18c responsible for its interaction with syntaxin 4, fragments of munc18c were generated and their interaction with syntaxin 4 examined in vivo by the yeast two-hybrid assay. In vitro protein–protein interaction studies were then used to confirm that the interaction between the proteins was direct. Full-length munc18c1–592, munc18c1–139 and munc18c1–225, but not munc18c226–592, munc18c1–100, munc18c43–139 or munc18c66–139, interacted with the cytoplasmic portion of syntaxin 4, Stx42–273, as assessed by yeast two-hybrid assay of growth on nutritionally deficient media and by β-galactosidase reporter induction. The N-terminal predicted helix-a-helix-b-helix-c region of syntaxin 4, Stx429–157, failed to interact with full-length munc18c1–592, indicating that a larger portion of syntaxin 4 is necessary for the interaction. The yeast two-hybrid results were confirmed by protein–protein interaction studies between Stx42–273 and glutathione S-transferase fusion proteins of munc18c. Full-length munc18c1–592, munc18c1–139 and munc18c1–225 interacted with Stx42–273 whereas munc18c1–100 did not, consistent with the yeast two-hybrid data. These data thus identify a region of munc18c between residues 1 and 139 as a minimal domain for its interaction with syntaxin 4.


2015 ◽  
Vol 12 (110) ◽  
pp. 20150573 ◽  
Author(s):  
A. Annibale ◽  
A. C. C. Coolen ◽  
N. Planell-Morell

Protein interaction networks (PINs) are popular means to visualize the proteome. However, PIN datasets are known to be noisy, incomplete and biased by the experimental protocols used to detect protein interactions. This paper aims at understanding the connection between true protein interactions and the protein interaction datasets that have been obtained using the most popular experimental techniques, i.e. mass spectronomy and yeast two-hybrid. We start from the observation that the adjacency matrix of a PIN, i.e. the binary matrix which defines, for every pair of proteins in the network, whether or not there is a link, has a special form, that we call separable. This induces precise relationships between the moments of the degree distribution (i.e. the average number of links that a protein in the network has, its variance, etc.) and the number of short loops (i.e. triangles, squares, etc.) along the links of the network. These relationships provide powerful tools to test the reliability of datasets and hint at the underlying biological mechanism with which proteins and complexes recruit each other.


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