scholarly journals YLMY Tyrosine Residue within the Cytoplasmic Tail of Newcastle Disease Virus Fusion Protein Regulates Its Surface Expression to Modulate Viral Budding and Pathogenicity

2021 ◽  
Vol 9 (3) ◽  
Author(s):  
Yawen Bu ◽  
Qingyuan Teng ◽  
Delan Feng ◽  
Lu Sun ◽  
Jia Xue ◽  
...  
Keyword(s):  
Cell Surface ◽  
Fusion Protein ◽  
Surface Expression ◽  
Protein Processing ◽  
Cell Surface Expression ◽  
Tyrosine Residue ◽  
F Protein ◽  
Tyrosine Residues ◽  
Amino Terminal ◽  
Viral Budding

The amino-terminal cytoplasmic domains of paramyxovirus fusion glycoproteins include trafficking signals that influence protein processing and cell surface expression. This study clarified that tyrosine residues at different positions in the YLMY motif in the cytoplasmic region of the F protein regulate F protein transportation, thereby affecting viral replication and pathogenicity.

scholarly journals Importance of Endocytosis for the Biological Activity of Cedar Virus Fusion Protein

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2054 ◽  
Author(s):  
Kerstin Fischer ◽  
Martin H. Groschup ◽  
Sandra Diederich
Keyword(s):  
Biological Activity ◽  
Cell Surface ◽  
Nipah Virus ◽  
Cytoplasmic Tail ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Highly Pathogenic ◽  
Proteolytic Activation ◽  
F Protein

Endocytosis plays a particular role in the proteolytic activation of highly pathogenic henipaviruses Hendra (HeV) and Nipah virus (NiV) fusion (F) protein precursors. These proteins require endocytic uptake from the cell surface to be cleaved by cellular proteases within the endosomal compartment, followed by recycling to the plasma membrane for incorporation into budding virions or mediation of cell-cell fusion. This internalization largely depends on a tyrosine-based consensus motif for endocytosis present in the cytoplasmic tail of HeV and NiV F. Given the large number of tyrosine residues present in the F protein cytoplasmic domain of Cedar virus (CedV), a closely related but low pathogenic henipavirus, we aimed to investigate whether CedV F protein undergoes signal-mediated endocytosis from the cell surface controlled by tyrosine-based motifs present in its cytoplasmic tail and whether endocytosis is relevant for its biological activity. Therefore, tyrosine-based signals were mutated, and mutations were assessed for their effect on F cell surface expression, endocytosis, and biological activity. A membrane-proximal YXXΦ motif and a C-terminal di-tyrosine motif are of particular importance for cell surface expression and endocytosis rate. Furthermore, our data strongly indicate the pivotal role of endocytosis for the biological activity of the CedV F protein.

Acidic amino acids increase fusion activity in the specific fusion domain of Newcastle disease virus fusion protein

2013 ◽  
Vol 59 (9) ◽  
pp. 641-644 ◽  
Author(s):  
Guijie Ren ◽  
Yunlong Zhuang ◽  
Keli Tian ◽  
Huiyu Li ◽  
Xueqin Diao ◽  
...  
Keyword(s):  
Amino Acids ◽  
Cell Surface ◽  
Cell Fusion ◽  
Newcastle Disease ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Fusion Activity ◽  
Wild Type ◽  
F Protein ◽  
Fusion Domain

To explore the effects of amino acids Gln and Asn within the specific fusion domain of fusion (F) protein on the specific membrane fusion in Newcastle disease virus (NDV), the mutants Q204E–Q205E and N245D were constructed in the specific fusion domain of F protein. The mutant genes were co-expressed with homologous or heterologous hemagglutinin–neuraminidase (HN) in BHK21 cells. Cell fusion functions of mutants were analyzed with Giemsa staining and reporter gene methods. Cell surface expression efficiency was analyzed with immunofluorescence assay and fluorescence-activated cell sorter analysis. Co-immunoprecipitation was performed to analyze the interaction of mutant F proteins with the homotypic HN protein. Both Q204E–Q205E and N245D mutations caused increased cell–cell fusion activity when they were co-expressed with homotypic HN protein. The mutant F proteins had slight changes in cell surface expression compared with that of wild-type F protein. The interactions of Q204E–Q205E or N245D with their homotypic HN increased significantly (P < 0.01) compared with the wild-type F protein. Neither Q204–Q205E nor N245D caused cell fusion in the presence of heterologous HN protein. Our data suggested that the residues Q204, Q205, and N245 play a critical role in the regulation of cell fusion. They may decrease the interaction of wild-type NDV F and NDV HN to suppress the fusion activity for survival of the infected host, which may enable a persistent virus infection and long-term virus reproduction and spread.

scholarly journals The Amino Terminal Lectin-Like Domain of Thrombomodulin Is Required for Constitutive Endocytosis

Blood ◽  
1997 ◽  
Vol 89 (2) ◽  
pp. 652-661 ◽  
Author(s):  
Edward M. Conway ◽  
Saskia Pollefeyt ◽  
Desiré Collen ◽  
Marta Steiner-Mosonyi
Keyword(s):  
Cell Surface ◽  
Protein C ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Immunogold Electron Microscopy ◽  
Wild Type ◽  
Hydrophobic Region ◽  
Cos Cells ◽  
Amino Terminal ◽  
Terminal Domain

Abstract Thrombomodulin (TM) is a multidomain protein that serves as a cofactor in a major natural anticoagulant system. To further characterize the structure-function of TM, we have transfected COS cells with different truncated forms of TM. In the first form, COS cells expressing TM that lacks the putative signal peptide (17 residues); the lectin-like, hydrophobic N-terminal domain (226 residues); and 12 residues of the first epidermal growth factor (EGF )-like repeat (COSdel.238 cells) were found to function normally with respect to TM transport to the cell surface and thrombin-dependent protein C activation. However, in contrast to wild-type TM, as visually studied by immunofluorescence and immunogold electron microscopy, the COSdel.238 cells did not constitutively internalize anti-TM–TM or thrombin-TM complexes. To identify the region responsible for mediating the endocytic process, deletant forms of TM lacking either the lectin-like region (residues 2-155) or the hydrophobic region of the N-terminal domain (residues 161-202) were expressed in COS cells (COSdel.2-155 and COSdel.161-202, respectively). Protein C cofactor activity was maintained in both cells. Although the COSdel.161-202 cells behaved similarly to wild-type TM-transfected cells, visual studies showed a lack of constitutive internalization of thrombin-TM or anti-TM–TM complexes in the COSdel.2-155 cells. We conclude that the lectin-like domain of human TM serves to regulate cell surface expression of TM via the endocytic route and therefore may also play a major physiologic role in controlling intracellular and extracellular accumulation of thrombin in a variety of biologic systems.

Persistent HIV Transcription Induces Sialyl-Lewis-X Glyco-Antigen Cell-Surface Expression

2020 ◽  
Author(s):  
Florent Colomb ◽  
Leila B. Giron ◽  
Leticia Kuri Cervantes ◽  
Tongcui Ma ◽  
Samson Adeniji ◽  
...  
Keyword(s):  
Cell Surface ◽  
Surface Expression ◽  
Sialyl Lewis X ◽  
Cell Surface Expression ◽  
Lewis X ◽  
Hiv Transcription ◽  
Sialyl Lewis
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