Journal: bioRxiv
Article Title: Cross-species interactome analysis uncovers a conserved selective autophagy mechanism for protein quality control in plants
doi: 10.1101/2024.09.08.611708
Figure Lengend Snippet: (A) CESAR has a conserved CUE domain. Protein domain architecture of MpCESAR. The CUE and ELKS-Rab6-interacting/CAST family member 1 (ELKS) domains are highlighted in purple and green, respectively. A schematic representation of the conservation-mapped AF2-predicted model for the CUE domain shown in Fig. S19A is highlighted. (B) MpCESAR binds ubiquitin in vitro . S. cerevisiae (Sc) VPS9 was used as positive control. (C-D) MpCESAR CUE domain is necessary for ubiquitin binding. MpCESAR ΔCUE =MpCESAR 47–987 . Bacterial lysates containing recombinant protein were mixed and pulled down with glutathione magnetic agarose beads. Input and bound proteins were visualized by immunoblotting with anti-GST or anti-MBP antibodies. (E) MpCESAR CUE binds different ubiquitin chain linkages with similar affinities. Halo-tagged MpCESAR CUE coupled to HaloLink resin was incubated with tetra-ubiquitin (Ub4) of the indicated linkage types. The captured materials were separated on 4-12% SDS-PAGE gel and silver stained. The asterisk indicates non-specific bands from Halo-MpCESAR CUE which have a similar electrophoretic mobility as K63-Ub4 chains. (F-G) Proteotoxic stress enhances AtCESAR2 association with TUBEs. 5-d-old A. thaliana seedlings expressing GFP-EV (GFP) or AtCESAR2-GFP in wild -type (Col-0) background were incubated in liquid ½ MS medium with 1% sucrose for 4h at 21°C (Control, C) or 37°C (Heat stress, HS) followed by 4h recovery phase at 21°C (panel F) or for 1h at 21°C in DMSO (D)-supplemented or 5 µM Bortezomib (B)-supplemented media followed by 1h recovery phase in fresh media (panel G) and used for co-immunoprecipitation. Plant lysates were incubated with Magne® HaloTag ® Beads conjugated with HaloTag-TUBE. Input and bound proteins were detected by immunoblotting using the respective antibodies as indicated. Total protein loading control was analysed by Amidoblack (AB) staining. Immunoblotting for bait is shown in Fig. S19E (related to ) and Fig. S19F (related to ). (H-I) Proteotoxic stress enhances AtCESAR1 association with TUBEs. 5-d-old A. thaliana seedlings expressing mCherry-EV (mCherry) or AtCESAR1-mCherry in wild -type (Col-0) background were incubated in liquid ½ MS medium with 1% sucrose for 4h at 21°C (Control, C) or 37°C (Heat stress, HS) followed by 4h recovery phase at 21°C (panel H) or for 1h at 21°C in DMSO (D)-supplemented or 5 µM Bortezomib (B)-supplemented media followed by 1h recovery phase in fresh media (panel I) and used for co-immunoprecipitation. Plant lysates were incubated with Magne® HaloTag ® Beads conjugated with HaloTag-TUBE. Input and bound proteins were detected by immunoblotting using the respective antibodies as indicated. Total protein loading control was analysed by Amidoblack (AB) staining. Immunoblotting for bait is shown in Fig. S19G (related to ) and Fig. S19H (related to ). (J-K) HS increases CESAR localization to the insoluble fraction. 5-d-old A. thaliana seedlings expressing either GFP-EV (GFP) or AtCESAR2-GFP (panel J), either mCherry-EV (mCherry) or AtCESAR1-mCherry (panel K) in wild -type (Col-0) background were incubated in liquid ½ MS medium with 1% sucrose for 4h at 21°C (Control, C) or 37°C (Heat stress, HS) followed by 4h recovery phase at 21°C. Soluble and pellet fractions were separated by centrifugation and normalized before immunoblotting using the respective antibodies as indicated. Total protein loading control was analysed by Amidoblack (AB) staining. (L) CESAR partitioning to the insoluble fraction is reversible. 5-d-old A. thaliana seedlings expressing AtCESAR1-mCherry in wild -type (Col-0) background were incubated in liquid ½ MS medium with 1% sucrose for 4h at 37°C followed by a 4 - hour recovery phase at 21°C. Soluble (input) and pellet fractions were separated by centrifugation, and pellet fraction was further sonicated in a water bath before immunoblotting using the respective antibodies as indicated. (M) TUBE interactors are differentially enriched in atg5 and cesar1 cesar2 . Protein abundance pattern represented by a heatmap as (Log2 (PSM+0.1) – mean PSM value per protein) for the 16 and 13 proteins belonging to clusters 8 and 3 in Fig. S20B, respectively. A full caption of the heatmap is shown in Fig. S20C. Rows were clustered using Euclidean distance and resulting dendrograms are omitted from the figures. (N) Insoluble proteins accumulate in the pellet fraction upon heat stress recovery. Dot plot representing protein abundance as Log2 (Fold change) for the ratio of two pairwise comparisons, cesar1 cesar2 vs. WT (x-axis) and atg5 vs. WT (y-axis). Dot size is mapped to reflect significant enrichment in atg5 represented as – Log10 (Adjusted P value). Enriched proteins in cesar1 cesar2 vs. WT or atg5 vs. WT are colored in purple and yellow, respectively. (O) Comparison between atg5 and cesar1 cesar2 pellet-enriched fractions. Venn diagram of the two overlapping pairwise comparisons in comparing proteins enriched in atg5 (yellow circle) or cesar1 cesar2 (purple circle) pellet fractions. (P-R) Analysis of protein features in the pellet-enriched fractions of atg5 and cesar1 cesar2 . Boxplots representing protein size (P), isoelectric point (Q) and relative aromaticity (R) of the indicated genotypes. TAIR10 proteome was used as a reference. Horizontal white lines within the boxes indicate the median and the top and bottom edges of the boxes represent the 3 rd and 1 st quartile, respectively. Vertical colored dashed lines indicate 1.5x the interquartile range. P values derived from pairwise comparisons by Wilcoxon-Mann-Whitney test are shown. ns, not significant. (S) Enriched proteins in cesar1 cesar2 pellets are highly hydrophobic. Line plots representing the hydrophobicity profiles along the protein sequence of pellet-enriched proteins in the indicated genotypes. The solid line represents the mean hydrophobicity and the shaded are represents the standard deviation. TAIR10 proteome was used as a reference. Protein hydrophobicity levels as defined by the Kyle-Doolittle scale is shown on the y-axis and proteins as defined by percentiles of its total sequence length are shown on the x-axis.
Article Snippet: For protein content analysis upon Bortezomib treatment, 7-d-old seedlings were incubated in liquid media with either DMSO or 50 μM of Bortezomib (Santa Cruz; CAS 179324-69-7) for 4 hours under control conditions, followed by a 1 to 4-hour recovery in fresh media.
Techniques: Ubiquitin Proteomics, In Vitro, Positive Control, Binding Assay, Recombinant, Western Blot, Incubation, SDS Page, Staining, Expressing, Control, Immunoprecipitation, Centrifugation, Sonication, Quantitative Proteomics, Comparison, Derivative Assay, MANN-WHITNEY, Sequencing, Standard Deviation