(A) The spacer and the C-terminus of p107 are intrinsically disordered (IUPred2a web interface, Sievers et al., 2011). (B) Clustal W alignment of conserved amino acid sequences of the p107 spacer …
Uncropped replicates of western blot images and PVDF membranes stained with Coomassie Blue used to quantitate B55α binding to conserved regions in the p107 spacer (top bar graph).
B55α signal was normalized to the GST-fusion protein signal (selected bands are marked with dashed white boxes and corrected for background from a band-less identical area).
Uncropped replicates of western blot images and PVDF membranes stained with Coomassie Blue or Ponceau S used to quantitate binding to B55α of conserved regions in the p107 R1–R2 construct (top bar graph) and R/K point mutant variants of p107 R1–R2 (lower bar graph).
Only the R/K mutants labeled blue were included in the quantitation.
(A) Complete Clustal W alignment of conserved amino acid sequences of the p107 spacer from different species. Three highly conserved regions within the spacer were identified, which are highlighted …
(A) ConSurf depiction of PP2A/B55α mapping amino acid conservation (where amino acids are color-coded by conservation). (B) Electrostatic predictions mapped to the surface of the PP2A/B55α structure …
Upper, middle, and lower western blot membranes for Figure 2D (replicate 1).
Western blot membranes for replicates 1–3.
All replicates were used for the quantitation shown in Figure 2E. The legends indicate the B55α variants used in this set of replicates. Relevant proteins and IgG (in the IP membranes) are indicated.
Western blot membranes for replicates 1–2 used for the quantitation shown in Figure 2E.
The legend indicates the B55α variants used in this set of replicates. Relevant proteins and IgG (in the IP membranes) are indicated.
(A) Structure of the PP2A/B55α holoenzyme (PDB:3DW8). (B) Table depicting complete list of Myc-tagged B55α mutants generated, as well as summarizing the effect on binding to p107 and PP2A/A or …
Western blot membranes for replicates used for the quantitation of Flag-pRB:Myc-B55α binding ratios shown in Figure 2—figure supplement 1 (middle).
The legends indicate the B55α variants used in this set of replicates. Relevant proteins and IgG (in the IP membranes) are indicated.
Western blot membranes for replicates used for the quantitation of Flag-pRB:Myc-B55α binding ratios shown in Figure 2—figure supplement 1 (middle).
The legends indicate the B55α variants used in this set of replicates. Relevant proteins and IgG (in the IP membranes) are indicated.
Western blot membranes for replicates used for the quantitation of Flag-pRB:Myc-B55α binding ratios shown in Figure 2—figure supplement 1 (middle).
The legends indicate the B55α variants used in this set of replicates. Relevant proteins and IgG (in the IP membranes) are indicated.
Upper, middle, and lower western blot membranes for Figure 2—figure supplement 1, bottom.
Boxes indicate approximate area shown in the figure. Relevant proteins are indicated.
(A) Dephosphorylation of GST-p107 R1R2 was performed using approximately 10 ng purified PP2A/B55α. The indicated time points were collected and samples were resolved via SDS-PAGE. Proteins were …
Uncropped blots and Coomassie-stained gels for Figure 3A-C.
Images in Figure 3A were generated from the boxed regions in each PVDF membrane. Comparable experiments are shown in Figure 4. Images in Figure 3B were generated from the boxed regions in replicate 1. Replicates 1–3 show comparable dephosphorylation of WT and MT p107 R1R2 by Coomassie Blue staining. The gel image in Figure 3C was generated form representative replicate 1, and the bands cut out for mass spectrometry are boxed.
(A) Phosphorylation of purified GST-p107 R1R2 was performed using 0.25 μg recombinant cyclin A/CDK2 and 5 μCi γ–32P. The indicated time points were collected and samples were resolved via SDS-PAGE. …
Uncropped Coomassie-stained gel, Phosphorimager exposure and western blots for Figure 3—figure supplement 1.
Dashed boxes correspond to the areas shown in Figure 3—figure supplement 1 (top). The 7.5’ sample was loaded after the 15” sample in error. The lane was omitted in the figure for clarity and the omitted lane marked with an asterisk.
(A) Approximately 10 ng of purified PP2A/B55α was used to dephosphorylate wildtype GST-p107 R1R2 or mutant constructs (GST-p107 R621A K623A and GST-p107 RxK K657A R659A) in a time-course experiment. …
Uncropped Coomassie-stained gels and blots for Figure 4A and B.
Images in Figure 4A were generated from the boxed regions in replicate 1 PVDF membrane and the Coomassie Blue-stained gel. Quantifications shown in Figure 4A of the ‘phospho’-p107 band were obtained from Coomassie Blue-stained gel replicates 1–3. Images in Figure 4B were generated from the boxed regions in replicate 1. A comparable experiment using an R1 peptide (R1-627TDS-AAA) variant that binds B55α (Figure 5B) showed delayed phosphorylation as R1, while R1-R621A and R2, which do not bind B55α (Figure 5A and C), did not inhibit dephosphorylation.
(A) PP2A/B55α purified from 293T-Flag-B55α cells was preincubated with synthetic p107 peptides and then used in pull-down assays with GST-p107 R1R2 constructs. Proteins were resolved via SDS-PAGE …
Uncropped upper membrane (anti-B55α) and lower membrane (anti-GST) western blots for Figure 5A and B.
Images in Figure 4A and B were generated from the boxed regions in replicate 1 PVDF membranes. B55α band intensities were normalized to the corresponding full-length GST-R1R2 band intensities.
Uncropped upper membrane (anti-B55α) and lower membrane (anti-GST) western blots for Figure 5B, C (three replicates) were used to quantitate peptide competition of B55α binding to GST-R1R2.
B55α band intensities were normalized to the corresponding full-length GST-R1R2 band intensities.
(A) Representative pulldowns were performed using purified PP2A/B55α (PP2A) and GST-p107 R1R2 with preincubations using mutant p107-derived synthetic peptides, phosphopeptides, and control peptides, …
Uncropped western blot images for panel B.
All the replicates for panel A are shown in Figure 5—source data 2.
(A) GFP-p107 R1 wildtype and mutant constructs were co-transfected with Myc-B55α wildtype and B55α-D197K mutant constructs into 293T cells and used for IPs with anti-GFP agarose conjugate. Input …
Uncropped upper membranes for Figure 6A and replicate experiments of endogenous B55α interaction with wildtype, but not mutant, GFP-R1-SLiM.
Mass spectrometry dataset used to generate the volcano plot shown in Figure 6.
Uncropped upper and lower membranes for Figure 6C and D (representative replicate 1 was selected for the C and D panels).
In (C), B55α-mediated dephosphorylation was quantitated using the pCDK substrate vs. Flag-p107 signal using the corresponding bands in the dashed boxes.
(Right) Quantification of Flag-p107/HA-E2F4 rations is shown.
(A) The ‘two-fragment’ model depicting B55α and PP2A/C with two modeled peptide fragments. Distances between the OE1/OE2 atoms of Glu and the NH1/NH2 atoms of Arg are shown in center. (B) A closer …
PyMOL session source data for Figure 7A.
PyMOL session source data for Figure 7B.
PyMOL session source data for Figure 7C and D.
PyMOL session source data for Figure 7E.
PyMOL session source data for Figure 7F.
(A) Density plot of distances between OE1/2 of Glu and NH1/2 of Arg in 520 peptide structures with the consensus sequence EPXXXPR. The red dot is the distance between OE1/2 of Glu and NH1/2 of Arg …
Distances between OE1/2 and NH1/2 for 520 peptide structures with the consensus sequence EPXXXPR retrieved from PDB.
R script file to generate density plots for Figure 7—figure supplement 1A and B.
PyMOL session source data for Figure 7—figure supplement 1B.
Distances of OE1/2 and NH1/2 between each peptide and two reference fragments for Figure 7—figure supplement 1C.
PyMOL session source data for Figure 7—figure supplement 1D.
PyMOL session source data for Figure 7—figure supplement 1E.
Model code.
(A) Comparison of the flexibility of the PP2A/A scaffold upon binding to the catalytic subunit and B subunits of the four distinct holoenzymes. B55/B is colored red, B56/B′ is colored yellow, …
PyMOL session source data for Figure 7—figure supplement 2A.
PyMOL session source data for Figure 7—figure supplement 2B.
Scaffold variation source data without regulatory subunit for Figure 7—figure supplement 2C.
Scaffold variation source data with B56 subunits for Figure 7—figure supplement 2D.
(A) Schematic of our proposed hypothetical consensus groove SLiM, p[ST]-P-x(4,10)-[RK]-V-x-x-[VI]-R, for TAU, MAP2, and the conserved p107 family member, p130, each of which contain residues that …
The bar graph represents the percent of proteins with a degenerate version of the SLiM, [ST]-P-x(4,10)-[RK]-[VIL]-x(2)-[VILM] in the proteome and in a dataset of B55α interactors (Hertz et al., 2016)…
Table of proteins containing the [ST]-P-x(4,10)-[RK]-[VIL]-x(2)-[VILM] sequence in a dataset of B55α interactors (Hertz et al., 2016) and potential in vitro B55α mitotic substrates (Kruse et al., 2020).
Two replicates of the experiment showed comparable results.
B55a binding to GST-R1R2 was determined in the presence or absence of OA to prevent dephosphorylation. Proteins were resolved via SDS-PAGE and detected by western blotting using anti-B55α and GST …
Expression of indicated proteins and phospho pRB was determined by western blot analysis.
Reagent type (species) or resource | Designation | Source or reference | Identifiers | Additional information |
---|---|---|---|---|
Antibody | CDK2(rabbit polyclonal) | Santa Cruz | sc-163 | WB(1:1000) |
Antibody | Cyclin A(mouse monoclonal) | Santa Cruz | sc-271682 | WB(1:1000) |
Antibody | Flag(mouse monoclonal) | Sigma | A8592-.2MG | WB(1:2500, 1:10,000) |
Antibody | Flag(mouse monoclonal) | GenScript | A00187 | IP (1 µg/mL) |
Antibody | GFP(rabbit monoclonal) | CST | 2956S | WB(1:1000) |
Antibody | GST(mouse monoclonal) | Santa Cruz | sc-138 | WB(1:1000) |
Antibody | PP2A Aβ subunit(goat polyclonal) | Santa Cruz | sc-6113 | WB(1:2000) |
Antibody | PP2A B subunit(100C1)(rabbit monoclonal) | CST | 2290S | WB(1:2000) |
Antibody | PP2A C subunit (1D6) (mouse monoclonal) | Millipore | 05-421 | WB(1:5000) |
Antibody | Phospho-CDK Substrate Motif(rabbit monoclonal) | CST | 9477S | WB(1:1000) |
Antibody | ECL Rabbit IgG, HRP-linked whole Ab (from donkey) | GE Healthcare | NA934V | WB/secondary antibody(1:10,000) |
Antibody | HA (12CA5)(mouse monoclonal) | Roche/Sigma | 11583816001 | WB(1:500) |
Antibody | ECL Mouse IgG, HRP-linked whole Ab (from donkey) | GE Healthcare | NA931V | WB/secondary antibody(1:10,000) |
Antibody | Mouse anti-goat IgG-HRP | Santa Cruz | sc-2354 | WB/secondary antibody(1:10,000) |
Antibody | Monoclonal ANTI-FLAG M2 antibody produced in mouse, ANTI-FLAG M2 Affinity Agarose Gel | Sigma | A2220 | IP (10 μL) |
Antibody | Anti-c-Myc Agarose Affinity Gel antibody produced in rabbit (polyclonal) | Sigma | A7470 | IP (10 μL) |
Antibody | GFP-Trap agarose beads | Chromotek | gta-10 | IP (5 μL) |
Peptide, recombinant protein | Synthetic peptides for competition assays | Biomatik | Custom | Sequence variant described in this paper |
Peptide, recombinant protein | DYKDDDDK peptide | GenScript | RP10586 | |
Peptide, recombinant protein | Recombinant cyclin A/CDK2 | Thermo Fisher | PV3267 | |
Peptide, recombinant protein | Purified recombinant B55α/PP2A holoenzyme | Zhao et al., 2019 | Trimeric Flag-B55α/PP2A holoenzyme purified from 293T cells. | |
Strain, strain background (Escherichia coli) | BL21-Gold (DE3) cells | Agilent | 230132 | To generate GST-Fusion proteins |
Cell line (Homo sapiens) | 293T cells | ATCC | CRL-3216 | Transient transfections and source of cell lysates |
Cell line (H. sapiens) | U-2 OS cells | ATCC | HTB-96 | Transient transfections |
Cell line (H. sapiens) | Expi293F cells | Thermo Fisher | A14528 | Purification of recombinant B55α |
Transfected construct (human) | Flag-B55α 293T cells | Zhao et al., 2019 | 293T cells stably transfected with pCPP-Flag-B55α and selected with puromycin | |
Commercial assay or kit | (AminoLink Plus Immobilization Kit) | Thermo Fisher Scientific | 44894 | |
Commercial assay or kit | Ser/Thr phosphatase assay kit | EMD Millipore | 17-127 | |
Commercial assay or kit | QuikChange II | Agilent | 200521 | |
Recombinant DNA reagent | pBOS GFP-H2B plasmid | Kanda et al., 1998 | ||
Recombinant DNA reagent | pcDNA3.4-K-GFP-RP1B | This paper | His6-green fluorescent protein-tag, a TEV cleavage | |
Recombinant DNA reagent | pTHMT | Peti and Page, Protein Expr. Purif. 51, 1–10 (2007) | N-terminal His6-Maltose Binding Protein (MBP)-tag, a TEV cleavage | |
Recombinant DNA reagent | pCPP-Flag-B55α | Zhao et al., 2019 | ||
Recombinant DNA reagent | pMSCV-puro-Myc-B55α | Jayadeva et al., 2010 | ||
Recombinant DNA reagent | pMSCV-puro-Myc-B55α variants | This paper | Generated by site-directed mutagenesis (primer sequences provided in Appendix table) | |
Recombinant DNA reagent | pCDNA5/FRT/TO-GFP-p107-R1 | This paper | Inserting wild-type or mutant p107-R1 gBlock Gene Fragments (IDT) into the pCDNA5/FRT/TO-GFP vector via the BamHI/Not sites | |
Recombinant DNA reagent | pGEX-2T-p107 spacer | Jayadeva et al., 2010 | ||
Recombinant DNA reagent | pGEX-2T-p107 spacer variants | This paper | Generated by site-directed mutagenesis (primer sequences provided in Appendix table) | |
Recombinant DNA reagent | pCDNA5/FRT/TO-GFP-p107-R1 | This paper | Inserting a gblock in pCDNA5/FRT/TO-GFP containing 4 copies of R1 | |
Recombinant DNA reagent | pCDNA5/FRT/TO-GFP-p107-R1-H/AxR/AV/AxxV/A | This paper | Inserting a gblock in pCDNA5/FRT/TO-GFP containing four mutant copies of R1. (gblock sequences provided in Appendix table) | |
Recombinant DNA reagent | pSG5-puro-Flag-p107 | Kurimchak et al., 2013 | ||
Recombinant DNA reagent | pCMV-Flag-p107 | Voorhoeve et al., 1999 | ||
Recombinant DNA reagent | pCMV-HA-E2F4 | Ginsberg et al., 1994 | ||
Recombinant DNA reagent | pRC-cyclin E | Addgene | #8963 | |
Software, algorithm | ConSurf | ConSurfAshkenazy et al., 2010 | ||
Software, algorithm | ImageJ software | |||
Software, algorithm | FlowJo v10 software | BD Biosciences | v10.8 | |
Software, algorithm | Clustal Omega | Sievers et al., 2011 |