Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: a Immunofluorescence images and quantification (n = 20) of SUMO1 (green) and SUMO2/3 (red) conjugation in RAW264.7 cells with or without STM 14028S infection (4 hpi). Scale bar, 10 µm. b Core SUMO cycle enzymes and their corresponding primary genes (blue). c, d Transcriptomic and proteomic analyses of SUMO cycle enzyme expression in RAW264.7 cells infected with STM 14028S vs uninfected controls (4 hpi; n = 3). e UBC9 mRNA expression in RAW264.7 cells during STM 14028S infection (0-6 hpi; n = 3). f Immunoblot analysis and quantification of UBC9 protein levels in STM 14028S-infected RAW264.7 cells (0-6 hpi; n = 3). *P < 0.05; ***P < 0.001; ns, not significant.

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Immunofluorescence, Conjugation Assay, Infection, Expressing, Western Blot

Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: a Schematic of the Y2H screening workflow and pairwise interaction validation strategy. b Representative positive colonies on selective plates; four colonies (blue arrows) correspond to Ube2i (encoding UBC9). c Sequencing analysis of positive clones showing that four independent clones encode Ube2i (orange). d Pairwise interaction assay validating the interaction between SseK1 and UBC9. e Co-IP in HEK293T cells confirming the interaction between SseK1 and UBC9. f In vitro pull-down assay demonstrating direct binding between purified SseK1 and UBC9. g BLI analysis showing the binding kinetics between SseK1 and UBC9 in vitro .

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Biomarker Discovery, Sequencing, Clone Assay, Co-Immunoprecipitation Assay, In Vitro, Pull Down Assay, Binding Assay, Purification

Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: a HEK293T cells expressing Flag-UBC9 were infected with STM WT or Δ sseK1 , followed by immunoprecipitation and immunoblot analysis of UBC9 Arg-GlcNAcylation. b In vitro enzymatic assays showing Arg-GlcNAcylation of bacterially expressed 6×His-UBC9, detected by immunoblotting. c MS/MS spectrum of Arg-GlcNAcylated Flag-UBC9 peptides. Corresponding b and y ions are indicated along the peptide sequence above the spectrum. d Immunoblot analysis and quantification (normalized to Coomassie-stained protein, n = 3) of Arg-GlcNAcylation of UBC9 and UBC9 R17A. **P < 0.01.

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Expressing, Infection, Immunoprecipitation, Western Blot, In Vitro, Tandem Mass Spectroscopy, Sequencing, Staining

Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: a Crystal structure of the UBC9-SUMO1 complex (PDB: 2UYZ). b Predicted structure of the UBC9-SUMO2 complex generated using AlphaFold3. Enlarged views of the UBC9-SUMO1 and UBC9-SUMO2 interfaces are highlighted in black boxes. Residues forming hydrogen bonds with UBC9 R17 are shown in stick representation. c Purification of 6×His-UBC9 from E. coli BL21(DE3) co-expressing pSseK1 and pUBC9, followed by immunoblot analysis of UBC9 Arg-GlcNAcylation. d Purification of SUMO1 and SUMO2 proteins from E. coli BL21(DE3) harboring pSUMO1 or pSUMO2, respectively. M, molecular weight marker. e, f MST analysis of the binding affinities between SUMO1 or SUMO2 and unmodified UBC9 or Arg-GlcNAcylated UBC9.

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Generated, Purification, Expressing, Western Blot, Molecular Weight, Marker, Binding Assay

Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: a Immunoblot analysis of UBC9 Arg-GlcNAcylation mediated by SseK1, SseK2, or SseK3. b AlphaFold-predicted structures of SseK1 (aa 29-336, red), SseK2 (aa 29-348, yellow), and SseK3 (aa 29-335, green), shown with structural alignment using PyMOL. c AlphaFold-modeled structure of the SseK1-UBC9 complex. The enlarged view of the lid-domain region is boxed in black. Residues in the SseK1 lid domain forming hydrogen bonds with UBC9 are shown in stick representation. d Sequence alignment of SseK1, SseK2, and SseK3 generated using ESPript 3.0. e Immunoblot analysis of UBC9 Arg-GlcNAcylation mediated by SseK1, SseK1 A332_Q336del, SseK3, and SseK3 R332delinsARHVQ. f Immunoblot analysis of SUMO2/3 conjugation in RAW264.7 cells infected with STM Δ sseK1 , STM Δ sseK1 complemented with SseK1, or STM Δ sseK1 complemented with either SseK1 D223_D225delinsAAA or SseK1 A332_Q336del (4 hpi). g Phylogenetic analysis of Salmonella Typhimurium SseK1 homologs. Protein sequences homologous to SseK1 (UniProt accession: A0A0H3NK84) were identified using BLASTP analysis against the UniProtKB reference proteomes and Swiss-Prot databases. Sequences with an E-value < 0.05 were selected for phylogenetic analysis. The phylogenetic tree was constructed and visualized using the Interactive Tree of Life (iTOL) online tool.

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Western Blot, Sequencing, Generated, Conjugation Assay, Infection, Construct

Journal: bioRxiv

Article Title: A bacterial effector blocks SUMOylation by steric occlusion of UBC9 via arginine-GlcNAcylation

doi: 10.64898/2026.03.06.710069

Figure Lengend Snippet: Approximately two hours after entering macrophages, Salmonella activates its T3SS-2 to deliver effector proteins, including SseK1, SseK2 and SseK3, into the cytoplasm. Among these effectors, SseK1 uniquely engages UBC9 through its unique lid domain and catalyzes arginine-GlcNAcylation of UBC9 at residue R17. This modification prevents UBC9 from forming the UBC9-SUMO thioester intermediate, thereby blocking SUMO conjugation onto a broad set of antimicrobial substrates and impairing their activity, stability or localization. By blocking this SUMO-dependent arm of the host immune response, Salmonella evades host antimicrobial defenses, thereby promoting its survival and enhancing virulence.

Article Snippet: Unique primary antibodies used in this study included UBC9 (CST, #4786), SUMO1 (Proteintech, 67557-1-lg), SUMO2/3 (Proteintech, 67154-1-lg), arginine-GlcNAcylation antibody (Abcam, EPR18251), Myd88 (Proteintech, 67969-1-lg), HSPA8 (Proteintech, 10654-1-AP), PDCD4 (Proteintech, 84162-3-RR).

Techniques: Residue, Modification, Blocking Assay, Conjugation Assay, Activity Assay

Journal: BMC Cancer

Article Title: FOXL2 + cancer-associated fibroblasts enhances epithelial ovarian cancer development via TGFβ/Smad signaling

doi: 10.1186/s12885-025-15364-6

Figure Lengend Snippet: FOXL2 SUMOylation intricately regulates increased expression in CAFs. ( A ) SUMOylation sites of FOXL2 was analyzed by SUMOplot™ analysis. Shown are the top 7 predicted lysine residues; ( B ) In vitro sumoylation assay was employed to confirm the predicted SUMOylation sites using HA-tagged wild-type (WT), or the K25R, K87R, K114R, K150R, and 4KR (where K25, K87, K114 and K150 were all mutated to R). Shown is a representative blot and densitometry analysis of SUMOylated-FOXL2/Total FOXL2; ( C ) The association between SUMOylation and FOXL2 stability was determined by western blotting in HEK-293T cells using α-HA. Cells were transfected with either HA-FOXL2-WT or HA-FOXL2-K25/87R (double mutant, 2KR). The membrane was stripped and re-probed with GAPDH to confirm equivalent loading. Shown is a representative blot and densitometry analysis of three technical replicates; ( D ) Cells were transfected with HA-FOXL2-WT or, HA-FOXL2-2KR ± His-SUMO1. CHX (100 µg/ml) was added to inhibit translation allowing tracking of FOXL2 stability in the presence and absence of His-SUMO1. Blots were probed with α-HA and re-probed with GAPDH to confirm equivalent loading. Shown is a representative blot and densitometry analysis of three technical replicates; ( E ) DMSO (control), MG132 (proteasome inhibitor) or chloroquine (lysosome inhibitor) were added into HEK-293T cells transfected with HA-FOXL2-WT or HA-FOXL2-2KR, before CHX (100 µg/ml) was added. Blots were probed with α-HA and re-probed with GAPDH to confirm equivalent loading. Shown is a representative blot; ( F ) IP assay was used to test the association between FOXL2 SUMOylation and ubiquitination. Lysates obtained from HEK-293T cells transfected with HA-FOXL2-WT or HA-FOXL2-2KR, along with FLAG-UBC9, were immunoprecipitated using α-HA antibody and then probed with α-FLAG antibody. Shown is a representative blot; *, *** P < 0.05, P < 0.001

Article Snippet: The different primary antibodies used were α-SUMO1 (67559-1-Ig, 1:3000), α-UBC9 (10070-1-AP, 1:2000), α-Vimentin (10366-1-AP, 1:5000), α-N-cadherin (22018-1-AP, 1:5000), α-E-cadherin (20874-1-AP, 1:20000) (Proteintech, Wuhan, China); α-HA (A02041, 1:800), α-His (A02050, 1:800), α-Flag (A02010, 1:800) (Abbkine, Wuhan, China); α-FOXL2 (ab246511, 1:1000), α-Snail (ab216347, 1:1000) (Abcam, Cambridge, MA, USA); and, α-Smad2/3 (D7G7, 1:1000), α-p-Smad2 (Ser465/467)/Smad3 (Ser423/425) (D27F4, 1:1000) (CST, Boston, MA, USA).

Techniques: Expressing, In Vitro, Western Blot, Transfection, Mutagenesis, Membrane, Control, Ubiquitin Proteomics, Immunoprecipitation

Journal: BMC Cancer

Article Title: FOXL2 + cancer-associated fibroblasts enhances epithelial ovarian cancer development via TGFβ/Smad signaling

doi: 10.1186/s12885-025-15364-6

Figure Lengend Snippet: FOXL2 SUMOylation requires SUMO1 and UBC9/UBE2I. ( A ) Putative interaction of FOXL2 with SUMO1, SUMO2, SUMO3, and SUMO4 was detected by String analysis ( https://cn.string-db.org/ ); ( B ) In vitro sumoylation assay was employed to confirm String analysis’s prediction of SUMO1, HEK-293T cells were transfected with HA-FOXL2-WT, FLAG-UBC9, and His-SUMO1-4. In vitro SUMOylation assay using Ni 2+ -NTA pull-down determined that FOXL2 was mainly modified by SUMO1. Shown is a representative blot; ( C ) In vitro sumoylation assay was employed to determine whether UBC9 is compulsorily required for FOXL2 SUMOylation. HEK-293T cells were transfected with HA-FOXL2-WT and His-SUMO1 ± FLAG-UBC9. In vitro SUMOylation using Ni 2+ -NTA pull-down assay determined that UBC9 is required for FOXL2 SUMOylation. Shown is a representative blot; ( D ) In vitro sumoylation assay was employed to determine whether UBC9 is compulsorily required for FOXL2 SUMOylation in CAFs. CAFs were transduced using either a non-targeting control shRNA or shRNA targeting UBC9 . Transduced cells were transfected with HA-FOXL2-WT and His-SUMO1. In vitro SUMOylation using Ni 2+ -NTA pull-down assay determined that UBC9 is required for FOXL2 SUMOylation. Shown is a representative blot

Article Snippet: The different primary antibodies used were α-SUMO1 (67559-1-Ig, 1:3000), α-UBC9 (10070-1-AP, 1:2000), α-Vimentin (10366-1-AP, 1:5000), α-N-cadherin (22018-1-AP, 1:5000), α-E-cadherin (20874-1-AP, 1:20000) (Proteintech, Wuhan, China); α-HA (A02041, 1:800), α-His (A02050, 1:800), α-Flag (A02010, 1:800) (Abbkine, Wuhan, China); α-FOXL2 (ab246511, 1:1000), α-Snail (ab216347, 1:1000) (Abcam, Cambridge, MA, USA); and, α-Smad2/3 (D7G7, 1:1000), α-p-Smad2 (Ser465/467)/Smad3 (Ser423/425) (D27F4, 1:1000) (CST, Boston, MA, USA).

Techniques: In Vitro, Transfection, Modification, Pull Down Assay, Control, shRNA