Journal: Frontiers in microbiology

Article Title: Expression of Human ACE2 N-terminal Domain, Part of the Receptor for SARS-CoV-2, in Fusion With Maltose-Binding Protein, E. coli Ribonuclease I and Human RNase A.

doi: 10.3389/fmicb.2021.660149

Figure Lengend Snippet: FIGURE 1 | SDS-PAGE analysis of maltose binding protein-angiotensin converting enzyme 2 N-terminal domain (MBP-ACE2NTD) fusion. (A) A schematic diagram of the fusion protein. (B) Total cellular proteins from IPTG-induced cells (NEB Express) containing the MBP-ACE2NTD fusion. Nine out of 11 clones tested here expressed the fusion (except #1 and #4). Clone #8 was chosen for further study. (C) MBP-ACE2NTD fusion expressed from IPTG induced cells (T7 Shuffle, lanes 1–4). Lane 1, total cellular protein; lane 2, flow-through from an amylose column; lane 3, eluted MBP-ACE2NTD protein from an amylose column; lane 4, MBP-ACE2NTD protein found in the pellet (inclusion body); lane 5, refolded MBP-ACE2NTD fusion protein from cell pellet (NEB Express); M, protein size marker (10–200 kDa, NEB). Arrows indicate the MBP-ACE2NTD protein, a truncated protein, and host MBP. (D) Purified MBP-ACE2NTD protein by amylose magnetic beads. Lane 1, refolded fusion; lanes 2 and 3, protein eluted in a Tris–HCl buffer (20 mM, pH 7.5) and sodium phosphate buffer (0.1 M, pH 8.0) with 10 mM maltose.

Article Snippet: Ab Mouse monoclonal anti-ACE2 Ab (catalog number #74512) and mouse anti-His tag Ab (catalog number 70796-3) were purchased from Cell Signaling Technologies (CST, MA) and EMC Millipore (Germany), respectively.

Techniques: SDS Page, Binding Assay, Clone Assay, Marker, Magnetic Beads

Journal: Frontiers in microbiology

Article Title: Expression of Human ACE2 N-terminal Domain, Part of the Receptor for SARS-CoV-2, in Fusion With Maltose-Binding Protein, E. coli Ribonuclease I and Human RNase A.

doi: 10.3389/fmicb.2021.660149

Figure Lengend Snippet: FIGURE 5 | SDS-PAGE and Western blot analysis of RNase I-ACE2NTD fusion and activity assays. (A) Schematic diagram of RNase I-ACENTD (6×His) fusion. (B) Western blot analysis of RNase I-ACE2NTD in total protein, supernatant (soluble), and refolded protein using anti-His mAb. (C) Same as in (B), except using anti-ACE2 mAb. (D) SDS-PAGE analysis of the refolded RNase I-ACE2NTD fusion and further purified protein by Ni magnetic beads and Ni spin column. (E) RNase I-ACE2NTD (refolded) ribonuclease activity on fluorescein (FL)-labeled RNA (300 nt) in NEB buffer 3. RNase I (6×His) and MBP-RNase I were used as positive controls. (F) Ribonuclease activity of RNase I-ACE2NTD (purified by Ni magnetic beads or Ni spin column) on SARS-CoV-2 RNA (50 mer). RNase If, a positive control. FAM-S, FAM-labeled substrate; FAM-P, FAM labeled cleavage product(s).

Article Snippet: Ab Mouse monoclonal anti-ACE2 Ab (catalog number #74512) and mouse anti-His tag Ab (catalog number 70796-3) were purchased from Cell Signaling Technologies (CST, MA) and EMC Millipore (Germany), respectively.

Techniques: SDS Page, Western Blot, Activity Assay, Magnetic Beads, Labeling, Positive Control

Journal: Frontiers in microbiology

Article Title: Expression of Human ACE2 N-terminal Domain, Part of the Receptor for SARS-CoV-2, in Fusion With Maltose-Binding Protein, E. coli Ribonuclease I and Human RNase A.

doi: 10.3389/fmicb.2021.660149

Figure Lengend Snippet: FIGURE 6 | Expression of hRNase A-ACE2NTD150 in T7 Express LysY/lacIq (C3013). (A) Schematic diagram of the fusion protein. (B) SDS-PAGE analysis of five isolates of hRNase A-ACE2NTD150 (five isolates with MBP signal peptide, five clones without MBP signal peptide). Total cell lysate of pET21b serves as a negative control. (C,D) Western blot analysis of the fusion proteins (soluble fraction/supernatant) by anti-His mAb and anti-ACE2 mAb.

Article Snippet: Ab Mouse monoclonal anti-ACE2 Ab (catalog number #74512) and mouse anti-His tag Ab (catalog number 70796-3) were purchased from Cell Signaling Technologies (CST, MA) and EMC Millipore (Germany), respectively.

Techniques: Expressing, SDS Page, Clone Assay, Negative Control, Western Blot

Journal: Science immunology

Article Title: TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes.

doi: 10.1126/sciimmunol.abc3582

Figure Lengend Snippet: Fig. 1. VSV-SARS-CoV-2 infects human small intestinal enteroids. (A) Mouse small intestinal cells were analyzed by scRNA-seq and resolved into 20 clusters based on gene expression profiles (left). Transcript levels of Cd26, Epcam, Cd44, Cd45, and Ace2 were indicated for different intestinal cell subsets. Clusters 10 and 18: intraepithelial lymphocytes; clusters 1, 2, 5, 8, 9, 17, 19, and 20: enterocytes; cluster 3: goblet cells; cluster 4: enteroendocrine cells; cluster 7: Tuft cells; cluster 11: crypt stem cells; cluster 12: Paneth cells. Each dot represents a single cell. Note that Ace2high cells are also positive for Cd26 and Epcam but negative for Cd44 and Cd45. (B) Human duodenum enteroids were cultured in the Transwell monolayer system using maintenance (MAINT) or differentiation (DIFF) conditions for 3 days. Monolayers were stained for ACE2 (red) and actin (phalloidin, white). Scale bars, 32 m. (C) Human duodenum enteroids in monolayer, cultured in either maintenance (MAINT) or differentiation (DIFF) conditions, were apically infected with 1.5 × 105 plaque-forming units (PFU) of VSV-SARS-CoV-2 [multiplicity of infection (MOI) = 0.3] for 24 hours. The expression of VSV-N was measured by RT-qPCR and normalized to that of GAPDH. p.i., post-infection. (D) Human duodenum enteroids in 3D Matrigel were cultured in maintenance (MAINT) medium or differentiation (DIFF) medium for 3 days and infected with 2.2 × 105 PFU of VSV-SARS-CoV-2 for 18 hours. Enteroids were stained for virus (green), actin (phalloidin, white), and nucleus (DAPI, blue). Scale bars, 50 m. (E) Same as (C) except that virus titers were mea- sured using a TCID50 assay instead of viral RNA levels by qPCR. (F) Same as (D) except that human ileum enteroids were used instead. Scale bars, 80 m. (G) Same as (D) except that human colon enteroids were used instead. Scale bars, 80 m. For all figures except (A), experiments were repeated at least three times with similar re- sults. (A) was performed once with small intestinal tissues pooled from three mice. Data are represented as mean ± SEM. Statistical significance is indicated (*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001).

Article Snippet: Samples were then stained with the following primary antibodies or fluorescent dyes: ACE2 (sc-390851 AF594, Santa Cruz Biotechnology), 4′,6-diamidino-2-phenylindole (DAPI) (P36962, Thermo Fisher Scientific), SARS-CoV-2 S [CR3022 human monoclonal antibody (58)], villin (sc-58897 AF488, Santa Cruz Biotechnology), and phalloidin (Alexa 647–conjugated, Thermo Fisher Scientific).

Techniques: Gene Expression, Cell Culture, Staining, Infection, Expressing, Quantitative RT-PCR, Virus, TCID50 Assay

Journal: Science immunology

Article Title: TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes.

doi: 10.1126/sciimmunol.abc3582

Figure Lengend Snippet: Fig. 2. VSV-SARS-CoV-2 and wild-type SARS-CoV-2 replicate in ACE2+ human mature enterocytes. (A) Human duodenum enteroids in monolayer, cultured in either maintenance (MAINT) or differentiation (DIFF) conditions, were apically or basolaterally infected with 1.5 × 105 PFU of VSV-SARS-CoV-2 for 24 hours. The expression of VSV-N was measured by RT-qPCR and normalized to that of GAPDH. (B) Supernatants in both apical and basal chambers were collected from (A) and were subjected to a TCID50 assay to measure the amount of infectious virus. (C) Differentiated duodenum enteroids in monolayer were apically infected with 2.5 × 105 PFU of infectious SARS-CoV-2 virus (MOI = 0.5) for 8 hours. The expression of SARS-CoV-2 N was measured by RT-qPCR using a TaqMan assay and normalized to that of GAPDH. (D) Differentiated ileum enteroids in monolayer were apically or basolaterally infected with 2.5 × 105 PFU of infectious SARS-CoV-2 virus (MOI = 0.5) for 8 hours. The expression of SARS-CoV-2 N was measured by RT-qPCR using a TaqMan assay and normalized to that of GAPDH. (E) Same as (C) except that enteroids were fixed and stained for SARS-CoV-2 S (green), ACE2 (red), and nucleus (DAPI, blue). Scale bars, 32 m. SARS-CoV-2–infected ACE2-positive cells are enlarged in the inset (yellow box). (F) SARS-CoV-2–infected duodenum monolayers were imaged along the Z stacks and sectioned for YZ planes (top) and reconstructed for 3D images (bottom). For all figures except (C) to (E), ex- periments were repeated at least three times with similar results. (C) to (E) were performed twice with technical duplicates in each experiment. Data are represented as mean ± SEM. Statistical significance is indicated (*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001).

Article Snippet: Samples were then stained with the following primary antibodies or fluorescent dyes: ACE2 (sc-390851 AF594, Santa Cruz Biotechnology), 4′,6-diamidino-2-phenylindole (DAPI) (P36962, Thermo Fisher Scientific), SARS-CoV-2 S [CR3022 human monoclonal antibody (58)], villin (sc-58897 AF488, Santa Cruz Biotechnology), and phalloidin (Alexa 647–conjugated, Thermo Fisher Scientific).

Techniques: Cell Culture, Infection, Expressing, Quantitative RT-PCR, TCID50 Assay, Virus, TaqMan Assay, Staining

Journal: Science immunology

Article Title: TMPRSS2 and TMPRSS4 promote SARS-CoV-2 infection of human small intestinal enterocytes.

doi: 10.1126/sciimmunol.abc3582

Figure Lengend Snippet: Fig. 3. TMPRSS2 and TMPRSS4, but not ST14, mediate SARS-CoV-2 S–mediated entry. (A) Bulk RNA-seq results of intestine-specific serine protease expression in HEK293, Huh7.5, H1-Hela, and HT-29 cells and human ileum enteroids. (B) HEK293 cells were transfected with pcDNA3.1-V5-ACE2, DDP4, or ANPEP for 24 hours (left), or transfected with indicated plasmid combination for 24 hours (right), and infected with 1.5 × 105 PFU of VSV-SARS-CoV-2 for 24 hours. The ex- pression of VSV-N was measured by RT-qPCR and normalized to that of GAPDH. (C) HEK293 cells stably expressing human ACE2 were transfected with SARS-CoV-2 S and TMPRSS2 or TMPRSS4 for 48 hours. Cells were treated with trypsin at 0.5 g/ml for 10 min. The levels of S and GAPDH were measured by Western blot. The intensity of bands was quantified by ImageJ and shown as percentage of the bottom band versus the top band in each lane. (D) HEK293 cells stably expressing human ACE2 were transfected with TMPRSS2 or TMPRSS4 for 24 hours, incubated with 5.8 × 105 PFU of VSV-SARS-CoV-2 on ice for 1 hour, washed with cold phosphate-buffered saline for three times, and shifted to 37°C for another hour. The expression of VSV-N was measured by RT-qPCR and normalized to that of GAPDH. (E) Wild-type (WT) or human ACE2-expressing HEK293 cells were transfected with SARS-CoV-2 S and GFP, with or without TMPRSS2 or TMPRSS4 for 24 hours. The red arrows highlight the formation of large syncytia. Scale bars, 100 m. For all figures except (A), experiments were repeated at least three times with similar results. RNA-seq in (A) was performed once with duplicate samples. Data are represented as mean ± SEM. Statistical sig- nificance is indicated (*P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001).

Article Snippet: Samples were then stained with the following primary antibodies or fluorescent dyes: ACE2 (sc-390851 AF594, Santa Cruz Biotechnology), 4′,6-diamidino-2-phenylindole (DAPI) (P36962, Thermo Fisher Scientific), SARS-CoV-2 S [CR3022 human monoclonal antibody (58)], villin (sc-58897 AF488, Santa Cruz Biotechnology), and phalloidin (Alexa 647–conjugated, Thermo Fisher Scientific).

Techniques: RNA Sequencing, Expressing, Transfection, Plasmid Preparation, Infection, Quantitative RT-PCR, Stable Transfection, Western Blot, Incubation, Saline

Journal: Journal of Chemical Theory and Computation

Article Title: Differential Interactions between Human ACE2 and Spike RBD of SARS-CoV-2 Variants of Concern

doi: 10.1021/acs.jctc.1c00965

Figure Lengend Snippet: (A) Average force profiles of WT (red), Alpha (blue), Beta (orange), Gamma (sky blue), Epsilon (green), Kappa (pink), and Delta (gray) variants as a function of the distance between the centers of mass of RBD and ACE2. (B) Initial snapshot of WT. Residues subjected to each mutation are shown as solid sticks (N501, K417, E484, L452, and T478). RBD and ACE2 are, respectively, colored in light gray and yellow. All N-glycans, water, and ions are hidden for clarity. (C) Initial snapshot of WT with clockwise 90° rotation along the normal from (B). All N-glycans are depicted in different colors. Any other residues, water, and ions are not shown for clarity.

Article Snippet: The recombinant human ACE2 protein (GenBank accession: AF291820.1, Sino Biological 10108-H08H; Wayne, PA) was labeled with RED-NHS (second Generation) dye using the Monolith Protein Labeling Kit (NanoTemper Technologies, MO-L011, München, Germany).

Techniques: Mutagenesis

Journal: Journal of Chemical Theory and Computation

Article Title: Differential Interactions between Human ACE2 and Spike RBD of SARS-CoV-2 Variants of Concern

doi: 10.1021/acs.jctc.1c00965

Figure Lengend Snippet: Two-dimensional contact maps at D = 53 Å. (A) Interacting residue pairs between RBD WT and ACE2. RBD residues subjected to mutation are shown in colored boxes at the bottom: (B) blue for Alpha, (C) orange for Beta, and (D) green for Epsilon. The contact frequency is numbered with colors from light blue to dark blue. Dark red and yellow colors on the map, respectively, represent increased and decreased interactions between RBD and ACE2 upon mutations.

Article Snippet: The recombinant human ACE2 protein (GenBank accession: AF291820.1, Sino Biological 10108-H08H; Wayne, PA) was labeled with RED-NHS (second Generation) dye using the Monolith Protein Labeling Kit (NanoTemper Technologies, MO-L011, München, Germany).

Techniques: Mutagenesis

Journal: Journal of Chemical Theory and Computation

Article Title: Differential Interactions between Human ACE2 and Spike RBD of SARS-CoV-2 Variants of Concern

doi: 10.1021/acs.jctc.1c00965

Figure Lengend Snippet: (A) The average number of contacts between RBD residue 501 and ACE2. (B, C) Representative snapshots at D = 53 Å of (B) Alpha variant and (C) WT. (D) Average number of contacts between RBD residue 417 and ACE2 and (E, F) their interacting residue pairs at D = 53 Å of (E) Beta and (F) Alpha variants. (G) Average number of contacts between RBD residue 478 and ACE2 and (H, I) key interaction pairs at D = 78 Å of (H) Delta and (I) Epsilon variants. The overall color scheme is the same as in Figure , and each mutated residue in each variant is shown using the same colors (i.e., red for WT, blue for Alpha, orange for Beta, green for Epsilon, and gray for Delta). Interacting residues are depicted as solid sticks, and residues losing their interactions are shown as transparent sticks. RBD and ACE2 are presented in light gray and yellow, respectively.

Article Snippet: The recombinant human ACE2 protein (GenBank accession: AF291820.1, Sino Biological 10108-H08H; Wayne, PA) was labeled with RED-NHS (second Generation) dye using the Monolith Protein Labeling Kit (NanoTemper Technologies, MO-L011, München, Germany).

Techniques: Variant Assay

Journal: Journal of Chemical Theory and Computation

Article Title: Differential Interactions between Human ACE2 and Spike RBD of SARS-CoV-2 Variants of Concern

doi: 10.1021/acs.jctc.1c00965

Figure Lengend Snippet: Binding affinities between RBD variants and ACE2 and its comparison with the simulation results. K d is obtained from microscale thermophoresis experiments. F WT / F is a ratio, where F WT and F are the respective maximum pulling force of WT and of each variant obtained from the SMD simulations.

Article Snippet: The recombinant human ACE2 protein (GenBank accession: AF291820.1, Sino Biological 10108-H08H; Wayne, PA) was labeled with RED-NHS (second Generation) dye using the Monolith Protein Labeling Kit (NanoTemper Technologies, MO-L011, München, Germany).

Techniques: Binding Assay, Microscale Thermophoresis, Variant Assay