scholarly journals SNX27 suppresses SARS-CoV-2 infection by inhibiting viral lysosome/late endosome entry

2022 ◽  
Vol 119 (4) ◽  
pp. e2117576119
Author(s):  
Bo Yang ◽  
Yuanyuan Jia ◽  
Yumin Meng ◽  
Ying Xue ◽  
Kefang Liu ◽  
...  
Keyword(s):  
Cell Surface ◽  
Host Cell ◽  
Viral Entry ◽  
Complex Structure ◽  
Pdz Domain ◽  
Late Endosome ◽  
Endocytic Pathway ◽  
Cell Surface Receptor ◽  
Binding Motif ◽  
Type I

After binding to its cell surface receptor angiotensin converting enzyme 2 (ACE2), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the host cell through directly fusing with plasma membrane (cell surface pathway) or undergoing endocytosis traveling to lysosome/late endosome for membrane fusion (endocytic pathway). However, the endocytic entry regulation by host cell remains elusive. Recent studies show ACE2 possesses a type I PDZ binding motif (PBM) through which it could interact with a PDZ domain-containing protein such as sorting nexin 27 (SNX27). In this study, we determined the ACE2-PBM/SNX27-PDZ complex structure, and, through a series of functional analyses, we found SNX27 plays an important role in regulating the homeostasis of ACE2 receptor. More importantly, we demonstrated SNX27, together with retromer complex (the core component of the endosomal protein sorting machinery), prevents ACE2/virus complex from entering lysosome/late endosome, resulting in decreased viral entry in cells where the endocytic pathway dominates. The ACE2/virus retrieval mediated by SNX27–retromer could be considered as a countermeasure against invasion of ACE2 receptor-using SARS coronaviruses.

scholarly journals A Single-Pass Type I Membrane Protein from the Apicomplexan Parasite Cryptosporidium parvum with Nanomolar Binding Affinity to Host Cell Surface

2021 ◽  
Vol 9 (5) ◽  
pp. 1015
Author(s):  
Tianyu Zhang ◽  
Xin Gao ◽  
Dongqiang Wang ◽  
Jixue Zhao ◽  
Nan Zhang ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cell Surface ◽  
Host Cell ◽  
Binding Affinity ◽  
Cryptosporidium Parvum ◽  
Host Cells ◽  
Watery Diarrhea ◽  
Type I ◽  
Single Pass ◽  
Host Cell Surface

Cryptosporidium parvum is a globally recognized zoonotic parasite of medical and veterinary importance. This parasite mainly infects intestinal epithelial cells and causes mild to severe watery diarrhea that could be deadly in patients with weakened or defect immunity. However, its molecular interactions with hosts and pathogenesis, an important part in adaptation of parasitic lifestyle, remain poorly understood. Here we report the identification and characterization of a C. parvum T-cell immunomodulatory protein homolog (CpTIPH). CpTIPH is a 901-aa single-pass type I membrane protein encoded by cgd5_830 gene that also contains a short Vibrio, Colwellia, Bradyrhizobium and Shewanella (VCBS) repeat and relatively long integrin alpha (ITGA) N-terminus domain. Immunofluorescence assay confirmed the location of CpTIPH on the cell surface of C. parvum sporozoites. In congruence with the presence of VCBS repeat and ITGA domain, CpTIPH displayed high, nanomolar binding affinity to host cell surface (i.e., Kd(App) at 16.2 to 44.7 nM on fixed HCT-8 and CHO-K1 cells, respectively). The involvement of CpTIPH in the parasite invasion is partly supported by experiments showing that an anti-CpTIPH antibody could partially block the invasion of C. parvum sporozoites into host cells. These observations provide a strong basis for further investigation of the roles of CpTIPH in parasite-host cell interactions.

scholarly journals Heparan Sulfate Facilitates Spike Protein-Mediated SARS-CoV-2 Host Cell Invasion and Contributes to Increased Infection of SARS-CoV-2 G614 Mutant and in Lung Cancer

2021 ◽  
Vol 8 ◽  
Author(s):  
Jingwen Yue ◽  
Weihua Jin ◽  
Hua Yang ◽  
John Faulkner ◽  
Xuehong Song ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Host Cell ◽  
Host Cells ◽  
Cell Surface Receptor ◽  
Spike Protein ◽  
Effective Prevention ◽  
Heparin Derivatives ◽  
Host Cell Surface

The severe acute respiratory syndrome (SARS)-like coronavirus disease (COVID-19) is caused by SARS-CoV-2 and has been a serious threat to global public health with limited treatment. Cellular heparan sulfate (HS) has been found to bind SARS-CoV-2 spike protein (SV2-S) and co-operate with cell surface receptor angiotensin-converting enzyme 2 (ACE2) to mediate SARS-CoV-2 infection of host cells. In this study, we determined that host cell surface SV2-S binding depends on and correlates with host cell surface HS expression. This binding is required for SARS-Cov-2 virus to infect host cells and can be blocked by heparin lyase, HS antagonist surfen, heparin, and heparin derivatives. The binding of heparin/HS to SV2-S is mainly determined by its overall sulfation with potential, minor contribution of specific SV2-S binding motifs. The higher binding affinity of SV2-S G614 mutant to heparin and upregulated HS expression may be one of the mechanisms underlying the higher infectivity of the SARS-CoV-2 G614 variant and the high vulnerability of lung cancer patients to SARS-CoV-2 infection, respectively. The higher host cell infection by SARS-CoV-2 G614 variant pseudovirus and the increased infection caused by upregulated HS expression both can be effectively blocked by heparin lyase and heparin, and possibly surfen and heparin derivatives too. Our findings support blocking HS-SV2-S interaction may provide one addition to achieve effective prevention and/treatment of COVID-19.

scholarly journals Significance of thiol-disulfide balance in SARS-CoV-2 infection

2021 ◽  
Vol 72 (3) ◽  
pp. 30-36
Author(s):  
Tatjana Simić
Keyword(s):  
Cell Surface ◽  
Host Cell ◽  
Protein Interactions ◽  
Viral Entry ◽  
Molecular Mechanisms ◽  
Alkylating Agents ◽  
Protein S ◽  
Protein Protein Interactions ◽  
Virus Surface ◽  
Host Cell Surface

Studies of the molecular mechanisms regarding interaction of different viruses with receptors on the host cell surface have shown that the viral entry depends on the specific relationship between free thiol (SH) groups and disulfides on the virus surface, as well as the thiol disulfide balance on the host cell surface. The presence of oxidizing compounds or alkylating agents, which disturb the thiol-disulfide balance on the surface of the virus, can also affect its infectious potential. Disturbed thiol-disulfide balance may also influence protein-protein interactions between SARS-CoV-2 protein S and ACE2 receptors of the host cell. This review presents the basic mechanisms of maintaining intracellular and extracellular thiol disulfide balance and previous experimental and clinical evidence in favor of impaired balance in SARS-CoV-2 infection. Besides, the results of the clinical application or experimental analysis of compounds that induce changes in the thiol disulfide balance towards reduction of disulfide bridges in proteins of interest in COVID-19 infection are presented.

scholarly journals Regulation of the endosomal SNX27-retromer by OTULIN

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Aurelia Stangl ◽  
Paul R. Elliott ◽  
Adan Pinto-Fernandez ◽  
Sarah Bonham ◽  
Luke Harrison ◽  
...  
Keyword(s):  
Cell Surface ◽  
Membrane Trafficking ◽  
Pdz Domain ◽  
Binding Motif ◽  
Ubiquitin Chain ◽  
Sorting Nexin ◽  
Catalytic Function ◽  
Retromer Complex ◽  
Mass Spectrometric Identification ◽  
Affinity Interaction

Abstract OTULIN (OTU Deubiquitinase With Linear Linkage Specificity) specifically hydrolyzes methionine1 (Met1)-linked ubiquitin chains conjugated by LUBAC (linear ubiquitin chain assembly complex). Here we report on the mass spectrometric identification of the OTULIN interactor SNX27 (sorting nexin 27), an adaptor of the endosomal retromer complex responsible for protein recycling to the cell surface. The C-terminal PDZ-binding motif (PDZbm) in OTULIN associates with the cargo-binding site in the PDZ domain of SNX27. By solving the structure of the OTU domain in complex with the PDZ domain, we demonstrate that a second interface contributes to the selective, high affinity interaction of OTULIN and SNX27. SNX27 does not affect OTULIN catalytic activity, OTULIN-LUBAC binding or Met1-linked ubiquitin chain homeostasis. However, via association, OTULIN antagonizes SNX27-dependent cargo loading, binding of SNX27 to the VPS26A-retromer subunit and endosome-to-plasma membrane trafficking. Thus, we define an additional, non-catalytic function of OTULIN in the regulation of SNX27-retromer assembly and recycling to the cell surface.

scholarly journals Divergent Traits and Ligand-Binding Features of the Cytomegalovirus CD48 Gene Family

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 23
Author(s):  
Pablo Martinez-Vicente ◽  
Domènec Farré ◽  
Elena Gracia-Latorre ◽  
Pablo Engel ◽  
Ana Angulo
Keyword(s):  
Cell Surface ◽  
Nk Cell ◽  
Viral Evolution ◽  
Costimulatory Molecule ◽  
Surface Protein ◽  
Gene Families ◽  
Biochemical Properties ◽  
Cell Surface Receptor ◽  
Type I ◽  
Independent Functions

The genesis of gene families through the capture of host genes and their subsequent duplication is a crucial process in the evolution of large DNA viruses. CD48 is a cell surface protein with an ectodomain composed of two immunoglobulin (Ig) domains. Via its N-terminal Ig domain, CD48 interacts with the cell surface receptor 2B4, triggering signal transduction events that regulate leukocyte cytotoxicity. We previously reported the presence of five CD48 homologs (vCD48s) in two related cytomegaloviruses, derived from a common host CD48 ancestor gene acquired by retrotranscription. Recently, we examined one member of this family, A43, showing that it acts as a functional viral decoy receptor, binding with high affinity and stability to 2B4 and impairing NK-cell cytotoxicity. Here, we have characterized the rest of the vCD48s. We show that they are highly glycosylated type I transmembrane proteins that display remarkably distinct features: dissimilar structures (e.g., different size stalks and cytoplasmic tails), biochemical properties, locations (cell surface/soluble), and temporal kinetic classes. We found that, in contrast to A43, none of them interacts with 2B4. Consistent with this, the molecular modeling of the N-terminal Ig domains of these vCD48s evidences significant changes in the numbers and lengths of their β-strands and inter-sheet loops that participate in the interaction of CD48 with 2B4. This suggests that these vCD48s have diverged to perform new 2B4-independent functions. Interestingly, we determined that one of them, S30, tightly binds CD2, a T- and NK-cell adhesion and costimulatory molecule whose primary ligand is CD58. Thus, altogether, our results show how a key host immune receptor captured by a virus can be subsequently remodeled during viral evolution to yield new molecules with improved affinities to their cognate receptors or with shifted binding specificities to additional immune targets, expanding the repertoire of viral immunoevasins.

scholarly journals Functional scintigraphy of the adrenal gland

2002 ◽  
Vol 147 (1) ◽  
pp. 13-28 ◽  
Author(s):  
D Rubello ◽  
C Bui ◽  
D Casara ◽  
MD Gross ◽  
LM Fig ◽  
...  
Keyword(s):  
Adrenal Gland ◽  
Cell Surface ◽  
Adrenal Cortex ◽  
Cell Surface Receptor ◽  
Cell Surface Receptors ◽  
Zona Fasciculata ◽  
Type I ◽  
Surface Receptors ◽  
Meta Iodo Benzyl Guanidine ◽  
And Storage

Over the last 30 years nuclear medicine imaging of the adrenal gland and its lesions has been achieved by the exploitation of a number of physiological characteristics of this organ. By seeking and utilising features which are quantitatively or qualitatively different from those of the adjacent tissues, functional depiction of the adrenal gland and its diseases, which in most cases retain the basic physiology of their tissue of origin, including both the cortex and the medulla, are now a useful clinical reality. Agents widely used in clinical practice include: (a) uptake and storage of radiolabelled cholesterol analogues via the low density lipoprotein (LDL) receptor and cholesterol ester storage pool in the adrenal cortex ((131)I-6-beta-iodomethyl-norcholesterol, (75)Se-selenomethyl-norcholesterol); (b) catecholamine type I, presynaptic, uptake mechanism and intracellular granule uptake and storage mechanism in the adrenal medulla and extra-adrenal paraganglia ((131)I-, (123)I- and (124)I-meta-iodo-benzyl-guanidine (MIBG), (18)F-metafluoro-benzyl-guanidine); (c) cell surface receptor binding of peptides/neurotransmitters/modulators such as for the family of five subtypes of somatostatin receptors ((123)I-tyr-octreotide, (111)In-DTPA-octreotide, (111)In-DOTA-octreotide and many others); (d) although not specific for the adrenal gland, increased glycolysis by tumours, particularly the most malignant varieties, (18)F-2-fluoro-d-deoxyglucose can thus be expected to depict certain malignant lesions such as malignant pheochromocytomas (particularly the minority which are not detected by MIBG) and adrenal incidentalomas (particularly when they occur in patients with known extra-adrenal malignancies). There are a variety of adrenal tissue characteristics with potential for exploitation but which are not currently in clinical use, and which may, nevertheless, have potential as imaging agents. These include: (a) inhibitors of adrenal cortical steroid hormone synthesis enzymes (e.g. radiolabelled analogues of metyrapone); (b) radiolabelled lipoproteins which bind to adrenocortical LDL receptors; (c) inhibitors of catecholamine biosynthesis enzymes (e.g. radiolabelled analogues of tyrosine and related amino acids); (d) cell surface receptors for various peptides and hormones which may be over-expressed on adrenal cortical or adrenal medullary tumours (e.g. radiolabelled analogues of ACTH on adrenocortical cells of zona fasciculata or zona glomerulosa origin, neurotransmitter/hormone message peptides binding to cell surface receptors such as bombesin, vasoactive intestinal polypeptide, cholecystokinin and opiate peptides); (e) the adrenal cortex can also synthesise cholesterol ab initio from acetate, and preliminary studies with (11)C-acetate positron emission tomography have shown interesting results.

scholarly journals An essential role for the Glut1 PDZ-binding motif in growth factor regulation of Glut1 degradation and trafficking

2009 ◽  
Vol 418 (2) ◽  
pp. 345-367 ◽  
Author(s):  
Heather L. Wieman ◽  
Sarah R. Horn ◽  
Sarah R. Jacobs ◽  
Brian J. Altman ◽  
Sally Kornbluth ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Glucose Uptake ◽  
Pdz Domain ◽  
Binding Motif ◽  
Lysosomal Degradation ◽  
Interacting Protein ◽  
Surface Localization ◽  
Cell Surface Localization ◽  
Growth Factor Regulation

Cell surface localization of the Glut (glucose transporter), Glut1, is a cytokine-controlled process essential to support the metabolism and survival of haemopoietic cells. Molecular mechanisms that regulate Glut1 trafficking, however, are not certain. In the present study, we show that a C-terminal PDZ-binding motif in Glut1 is critical to promote maximal cytokine-stimulated Glut1 cell surface localization and prevent Glut1 lysosomal degradation in the absence of growth factor. Disruption of this PDZ-binding sequence through deletion or point mutation sharply decreased surface Glut1 levels and led to rapid targeting of internalized Glut1 to lysosomes for proteolysis, particularly in growth factor-deprived cells. The PDZ-domain protein, GIPC (Gα-interacting protein-interacting protein, C-terminus), bound to Glut1 in part via the Glut1 C-terminal PDZ-binding motif, and we found that GIPC deficiency decreased Glut1 surface levels and glucose uptake. Unlike the Glut1 degradation observed on mutation of the Glut1 PDZ-binding domain, however, GIPC deficiency resulted in accumulation of intracellular Glut1 in a pool distinct from the recycling pathway of the TfR (transferrin receptor). Blockade of Glut1 lysosomal targeting after growth factor withdrawal also led to intracellular accumulation of Glut1, a portion of which could be rapidly restored to the cell surface after growth factor stimulation. These results indicate that the C-terminal PDZ-binding motif of Glut1 plays a key role in growth factor regulation of glucose uptake by both allowing GIPC to promote Glut1 trafficking to the cell surface and protecting intracellular Glut1 from lysosomal degradation after growth factor withdrawal, thus allowing the potential for a rapid return of intracellular Glut1 to the cell surface on restimulation.

scholarly journals Insertional Mutations in Herpes Simplex Virus Type 1 gL Identify Functional Domains for Association with gH and for Membrane Fusion

2009 ◽  
Vol 83 (22) ◽  
pp. 11607-11615 ◽  
Author(s):  
Qing Fan ◽  
Erick Lin ◽  
Patricia G. Spear
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Surface ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Viral Entry ◽  
Cell Surface Receptor ◽  
Cell Surface Expression ◽  
Conserved Domain ◽  
Simplex Virus

ABSTRACT Glycoprotein L (gL) is one of four glycoproteins required for the entry of herpes simplex virus (HSV) into cells and for virus-induced cell fusion. This glycoprotein oligomerizes with gH to form a membrane-bound heterodimer but can be secreted when expressed without gH. Twelve unique gL linker-insertion mutants were generated to identify regions critical for gH binding and gH/gL processing and regions essential for cell fusion and viral entry. All gL mutants were detected on the cell surface in the absence of gH, suggesting incomplete cleavage of the signal peptide or the presence of a cell surface receptor for secreted gL. Coexpression with gH enhanced the levels of cell surface gL detected by antibodies for all gL mutants except those that were defective in their interactions with gH. Two insertions into a conserved region of gL abrogated the binding of gL to gH and prevented gH expression on the cell surface. Three other insertions reduced the cell surface expression of gH and/or altered the properties of gH/gL heterodimers. Altered or absent interaction of gL with gH was correlated with reduced or absent cell fusion activity and impaired complementation of virion infectivity. These results identify a conserved domain of gL that is critical for its binding to gH and two noncontiguous regions of gL, one of which contains the conserved domain, that are critical for the gH/gL complex to perform its role in membrane fusion.

scholarly journals Cytoplasmic short linear motifs in ACE2 and integrin β3 link SARS-CoV-2 host cell receptors to endocytosis and autophagy

2020 ◽  
Author(s):  
Johanna Kliche ◽  
Muhammad Ali ◽  
Ylva Ivarsson
Keyword(s):  
Host Cell ◽  
Pdz Domain ◽  
Binding Motif ◽  
Angiotensin Converting Enzyme 2 ◽  
Cell Receptors ◽  
Short Linear Motifs ◽  
Integrin Β3 ◽  
Cytoplasmic Tails ◽  
Linear Motifs ◽  
Clathrin Adaptor

AbstractThe spike protein of the SARS-CoV-2 interacts with angiotensin converting enzyme 2 (ACE2) and enters the host cell by receptor-mediated endocytosis. Concomitantly, evidence is pointing to the involvement of additional host cell receptors, such as integrins. The cytoplasmic tails of ACE2 and integrin β3 contain a plethora of predicted binding motifs. Here, we confirm the functionality of some of these motifs through affinity measurements. The class I PDZ binding motif in the ACE2 cytoplasmic tail binds the first PDZ domain of the scaffold protein NHERF3. The clathrin-adaptor subunit AP2 μ2 interacts with an endocytic motif in the ACE2 with low affinity and the interaction is abolished by phosphorylation of Tyr781. Furthermore, the C-terminal region of integrin b3 contains a LC3-interacting region, and its interaction with ATG8 domains is enhanced by phosphorylation. Together, our data provides possible molecular links between host cell receptors and endocytosis and autophagy.One sentence summaryAffinity measurements confirmed binding of short linear motifs in the cytoplasmic tails of ACE2 and integrin β3, thereby linking the receptors to endocytosis and autophagy.

scholarly journals Analysis of the Role of N-glycosylation in Cell-surface expression, Function and Binding Properties of SARS-CoV-2 receptor ACE2

2021 ◽  
Author(s):  
Alberto Brandariz-Nuñez ◽  
Raymond R Rowland
Keyword(s):  
Cell Surface ◽  
Viral Entry ◽  
Biological Activities ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Type I ◽  
Protein Activity ◽  
Host Cell Membrane ◽  
S Protein

Human angiotensin I-converting enzyme 2 (hACE2) is a type-I transmembrane glycoprotein that serves as the major cell entry receptor for SARS-CoV and SARS-CoV-2. The viral spike (S) protein is required for attachment to ACE2 and subsequent virus-host cell membrane fusion. Previous work has demonstrated the presence of N-linked glycans in ACE2. N-glycosylation is implicated in many biological activities, including protein folding, protein activity, and cell surface expression of biomolecules. However, the contribution of N-glycosylation to ACE2 function is poorly understood. Here, we examined the role of N-glycosylation in the activity and localization of two species with different susceptibility to SARS-CoV-2 infection, porcine ACE2 (pACE2) and hACE2. The elimination of N-glycosylation by tunicamycin (TM) treatment or mutagenesis, showed that N-glycosylation is critical for the proper cell surface expression of ACE2 but not for its carboxiprotease activity. Furthermore, nonglycosylable ACE2 localized predominantly in the endoplasmic reticulum (ER) and not at the cell surface. Our data also revealed that binding of SARS-CoV and SARS-CoV-2 S protein to porcine or human ACE2 was not affected by deglycosylation of ACE2 or S proteins, suggesting that N-glycosylation plays no role in the interaction between SARS coronaviruses and the ACE2 receptor. Impairment of hACE2 N-glycosylation decreased cell to cell fusion mediated by SARS-CoV S protein but not SARS-CoV-2 S protein. Finally, we found that hACE2 N-glycosylation is required for an efficient viral entry of SARS-CoV/SARS-CoV-2 S pseudotyped viruses, which could be the result of low cell surface expression of the deglycosylated ACE2 receptor.

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