scholarly journals Destabilization of EpCAM dimer is associated with increased susceptibility towards cleavage by TACE

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11484
Author(s):  
Tomaž Žagar ◽  
Miha Pavšič ◽  
Aljaž Gaber
Keyword(s):  
Surface Protein ◽  
Cleavage Sites ◽  
Monomeric Form ◽  
Oligomeric State ◽  
Nuclear Signaling ◽  
Regulated Intramembrane Proteolysis ◽  
Promising Therapeutic Target ◽  
Dimerization Interface ◽  
Dimeric Form ◽  
Factor Α

The cell-surface protein EpCAM is a carcinoma marker utilized in diagnostics and prognostics, and a promising therapeutic target. It is involved in nuclear signaling via regulated intramembrane proteolysis (RIP). Many aspects of this process are not fully understood, including the events at the molecular level leading to the exposure of cleavage sites, buried at the dimerization interface. To investigate the effect of dimer stability on cleavage susceptibility we prepared two mutants of human EpCAM ectodomain: a monomeric form, and a disulfide-stabilized dimeric form. We show that the disulfide-stabilized dimer is resistant to tumor necrosis factor-α-converting enzyme (TACE) cleavage, while the monomeric form is more susceptible than the predominantly dimeric wild type. This provides experimental evidence that the oligomeric state of EpCAM is a determinant in RIP and demonstrates the usefulness of the oligomeric state-specific mutants in investigations of EpCAM biological function.

scholarly journals Cryo-EM Structure of a Tetrameric Photosystem I from Chroococcidiopsis TS-821, a Thermophilic, Non-heterocyst-forming Cyanobacteria

2020 ◽  
Author(s):  
Dmitry Semchonok ◽  
Jyotirmoy Mondal ◽  
Connor Cooper ◽  
Katrina Schlum ◽  
Meng Li ◽  
...  
Keyword(s):  
Excitation Energy ◽  
Photosystem I ◽  
Bioinformatics Analysis ◽  
Oxygenic Photosynthesis ◽  
Monomeric Form ◽  
Oligomeric State ◽  
Unicellular Cyanobacterium ◽  
Photosynthetic Organisms ◽  
Conserved Regions ◽  
Evolutionary Step

Abstract Photosystem I (PSI) is one of two the photosystems involved in oxygenic photosynthesis. PSI of cyanobacteria exists in monomeric, trimeric, and tetrameric forms, which is in contrast to the strictly monomeric form of PSI in plants and algae. The tetrameric organization raises questions about its structural, physiological, and evolutional significance. Here we report the ~3.9 Å resolution cryo-EM structure of tetrameric PSI from the thermophilic, unicellular cyanobacterium Chroococcidiopsis sp. TS-821. The structure resolves all 44 subunits and 448 cofactor molecules. We conclude that the tetramer is arranged via two different interfaces resulting from a dimer-of-dimers organization. The localization of chlorophyll molecules permits an excitation energy pathway within and between adjacent monomers. Bioinformatics analysis reveals conserved regions in PsaL subunit that correlate with the oligomeric state. Tetrameric PSI may function as a key evolutionary step between the trimeric and monomeric forms of PSI organization in photosynthetic organisms.

scholarly journals Structure of the merozoite surface protein 1 from Plasmodium falciparum

2021 ◽  
Vol 7 (23) ◽  
pp. eabg0465
Author(s):  
Patricia M. Dijkman ◽  
Tanja Marzluf ◽  
Yingyi Zhang ◽  
Shih-Ying Scott Chang ◽  
Dominic Helm ◽  
...  
Keyword(s):  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Coiled Coils ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Merozoite Surface Protein 1 ◽  
Dimerization Interface ◽  
Structural Insights ◽  
Promising Vaccine Candidate

The merozoite surface protein 1 (MSP-1) is the most abundant protein on the surface of the erythrocyte-invading Plasmodium merozoite, the causative agent of malaria. MSP-1 is essential for merozoite formation, entry into and escape from erythrocytes, and is a promising vaccine candidate. Here, we present monomeric and dimeric structures of full-length MSP-1. MSP-1 adopts an unusual fold with a large central cavity. Its fold includes several coiled-coils and shows structural homology to proteins associated with membrane and cytoskeleton interactions. MSP-1 formed dimers through these domains in a concentration-dependent manner. Dimerization is affected by the presence of the erythrocyte cytoskeleton protein spectrin, which may compete for the dimerization interface. Our work provides structural insights into the possible mode of interaction of MSP-1 with erythrocytes and establishes a framework for future investigations into the role of MSP-1 in Plasmodium infection and immunity.

scholarly journals GroEL protein of the Leptospira spp. interacts with host proteins and induces cytokines secretion on macrophages

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Joana Dias Ho ◽  
Luiz Eduardo Massao Takara ◽  
Denize Monaris ◽  
Aline Patrícia Gonçalves ◽  
Antonio Francisco Souza-Filho ◽  
...  
Keyword(s):  
Surface Protein ◽  
Wide Distribution ◽  
Renal Tubules ◽  
Dependent Manner ◽  
Host Proteins ◽  
Host Interaction ◽  
Groel Protein ◽  
Factor Α ◽  
Dose Dependent

Abstract Background Leptospirosis is a zoonotic disease caused by infection with spirochetes from Leptospira genus. It has been classified into at least 17 pathogenic species, with more than 250 serologic variants. This wide distribution may be a result of leptospiral ability to colonize the renal tubules of mammalian hosts, including humans, wildlife, and many domesticated animals. Previous studies showed that the expression of proteins belonging to the microbial heat shock protein (HSP) family is upregulated during infection and also during various stress stimuli. Several proteins of this family are known to have important roles in the infectious processes in other bacteria, but the role of HSPs in Leptospira spp. is poorly understood. In this study, we have evaluated the capacity of the protein GroEL, a member of HSP family, of interacting with host proteins and of stimulating the production of cytokines by macrophages. Results The binding experiments demonstrated that the recombinant GroEL protein showed interaction with several host components in a dose-dependent manner. It was also observed that GroEL is a surface protein, and it is secreted extracellularly. Moreover, two cytokines (tumor necrosis factor-α and interleukin-6) were produced when macrophages cells were stimulated with this protein. Conclusions Our findings showed that GroEL protein may contribute to the adhesion of leptospires to host tissues and stimulate the production of proinflammatory cytokines during infection. These features might indicate an important role of GroEL in the pathogen-host interaction in the leptospirosis.

Tmem27 dimerization, deglycosylation, plasma membrane depletion, and the extracellular Phe-Phe motif are negative regulators of cleavage by Bace2

2012 ◽  
Vol 393 (6) ◽  
pp. 473-484 ◽  
Author(s):  
Daria Esterházy ◽  
Pinar Akpinar ◽  
Markus Stoffel
Keyword(s):  
Plasma Membrane ◽  
Mutational Analysis ◽  
Cell Mass ◽  
Surface Protein ◽  
Cysteine Residue ◽  
Cleavage Sites ◽  
Amino Acid Residues ◽  
Β Cell ◽  
Glucose Stimulation ◽  
Disease States

Abstract The pancreatic β-cell surface protein Tmem27 is promotes the preservation of functional β-cell mass. It is a selective substrate of the protease Bace2, yet the intramolecular features of Tmem27 that regulate its processing by this sheddase have not been characterized. In particular, the importance of homodimerization, glycosylation, trafficking to the plasma membrane (PM), the existence of multiple cleavage sites, and the amino acid residues that govern these features are currently unknown. Using Tmem27 mutational analysis and multiple biochemical approaches, we here show that Tmem27 dimerization is a dynamic process mediated by its intracellular cysteine residue and that prevents Tmem27 cleavage, that extracellular asparagine glycosylation is essential for Tmem27 trafficking to the PM and its processing by Bace2, that the amount of Tmem27 at the PM is proportional to its total cell levels upon glucose stimulation and Bace2 inhibition, and that the double phenylalanine motif in the Tmem27 cleavage site is an intramolecular Bace2 inhibitor. These findings define structural properties of Tmem27 that affect the susceptibility to its protease Bace2 and have implications for the efficiency with which Tmem27 and other Bace2 substrates are cleaved in normal and disease states.

Expression in mammalian cell cultures reveals interdependent, but distinct, functions for Star and Rhomboid proteins in the processing of the Drosophila transforming-growth-factor-α homologue Spitz

2002 ◽  
Vol 363 (2) ◽  
pp. 347-352 ◽  
Author(s):  
John C. PASCALL ◽  
Jane E. LUCK ◽  
Kenneth D. BROWN
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Mammalian Cells ◽  
Egf Receptor ◽  
Transforming Growth Factor ◽  
Surface Protein ◽  
Immunocytochemical Staining ◽  
Transforming Growth Factor Α ◽  
Mammalian Cell Cultures ◽  
Factor Α

We report here distinct interdependent functions for two proteins, Star and Rhomboid, that are key determinants of the epidermal-growth-factor (EGF)-receptor signalling pathway in Drosophila. When we expressed the Drosophila EGF-receptor ligand Spitz in mammalian cells, the protein failed to traffic to the plasma membrane, as assessed by either cell-surface protein biotinylation or immunocytochemical staining. However, when we co-expressed Star with Spitz, trafficking of Spitz to the cell surface could be demonstrated. Only when we co-expressed Spitz, Star and Rhomboid could the release of soluble Spitz protein into the medium be shown. Taken together, our results indicate that Star is required for the intracellular trafficking of Spitz, and that Rhomboid is essential for the release of soluble Spitz protein from cells.

scholarly journals Four crystal structures of human LLT1, a ligand of human NKR-P1, in varied glycosylation and oligomerization states

2015 ◽  
Vol 71 (3) ◽  
pp. 578-591 ◽  
Author(s):  
Tereza Skálová ◽  
Jan Bláha ◽  
Karl Harlos ◽  
Jarmila Dušková ◽  
Tomáš Koval' ◽  
...  
Keyword(s):  
Natural Killer Cells ◽  
Natural Killer ◽  
Crystal Structures ◽  
Outer Part ◽  
Monomeric Form ◽  
X Ray Diffraction ◽  
Killer Cells ◽  
X Ray ◽  
Loop Region ◽  
Dimeric Form

Human LLT1 is a C-type lectin-like ligand of NKR-P1 (CD161, geneKLRB1), a C-type lectin-like receptor of natural killer cells. Using X-ray diffraction, the first experimental structures of human LLT1 were determined. Four structures of LLT1 under various conditions were determined: monomeric, dimeric deglycosylated after the firstN-acetylglucosamine unit in two forms and hexameric with homogeneous GlcNAc2Man5glycosylation. The dimeric form follows the classical dimerization mode of human CD69. The monomeric form keeps the same fold with the exception of the position of an outer part of the long loop region. The hexamer of glycosylated LLT1 consists of three classical dimers. The hexameric packing may indicate a possible mode of interaction of C-type lectin-like proteins in the glycosylated form.

scholarly journals Dimerization of SARS-CoV-2 nucleocapsid protein affects sensitivity of ELISA based diagnostics of COVID-19

2021 ◽  
Author(s):  
Wajihul Hasan Khan ◽  
Nida Khan ◽  
Avinash Mishra ◽  
Surbhi Gupta ◽  
Vikrant Bansode ◽  
...  
Keyword(s):  
Nucleocapsid Protein ◽  
Accessible Surface Area ◽  
Solvent Accessible Surface Area ◽  
Enzyme Linked Immunosorbent Assay ◽  
Monomeric Form ◽  
N Protein ◽  
Diagnostic Assays ◽  
Antigenic Properties ◽  
Dimeric Form ◽  
Accessible Surface

Diagnostics has played a significant role in effective management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nucleocapsid protein (N protein) is the primary antigen of the virus for development of sensitive diagnostic assays. Thus far, limited knowledge exists about the antigenic properties of the N protein. In this paper, we demonstrate the significant impact of dimerization of SARS-CoV-2 nucleocapsid protein on sensitivity of enzyme-linked immunosorbent assay (ELISA) based diagnostics of COVID-19. The expressed purified protein from E.coli consists of two forms, dimeric and monomeric forms, which have been further characterized by biophysical and immunological means. Indirect ELISA indicated elevated susceptibility of the dimeric form of the nucleocapsid protein for identification of protein-specific monoclonal antibody as compared to the monomeric form of the protein. These findings have also been confirmed with the modelled structure of monomeric and dimeric nucleocapsid protein via HHPred software and its solvent accessible surface area, which indicates higher stability and antigenicity of the dimeric type as compared to the monomeric form. It is evident that use of the dimeric form will increase the sensitivity of the current nucleocapsid dependent ELISA for rapid COVID-19 diagnostic. Further, the results indicate that monitoring and maintaining of the monomer-dimer composition is critical for accurate and robust diagnostics.

Sign in / Sign up

Export Citation Format

Share Document