PP2A/B55α substrate recruitment as defined by the retinoblastoma-related protein p107
- Temple University Lewis Katz School of Medicine, United States
- Fox Chase Cancer Center, United States
- University of Arizona, United States
- Hitchcock Medical Center at Dartmouth, United States
- UConn Health, United States
Abstract
Protein phosphorylation is a reversible post-translation modification essential in cell signaling. This study addresses a long-standing question as to how the most abundant serine/threonine Protein Phosphatase 2 (PP2A) holoenzyme, PP2A/B55α, specifically recognizes substrates and presents them to the enzyme active site. Here, we show how the PP2A regulatory subunit B55α recruits p107, a pRB-related tumor suppressor and B55α substrate. Using molecular and cellular approaches, we identified a conserved region 1 (R1, residues 615-626) encompassing the strongest p107 binding site. This enabled us to identify an 'HxRVxxV619-625' short linear motif (SLiM) in p107 as necessary for B55α binding and dephosphorylation of the proximal pSer-615 in vitro and in cells. Numerous B55α/PP2A substrates, including TAU, contain a related SLiM C-terminal from a proximal phosphosite, 'p[ST]-P-x(4,10)-[RK]-V-x-x-[VI]-R'. Mutation of conserved SLiM residues in TAU dramatically inhibits dephosphorylation by PP2A/B55α, validating its generality. A data-guided computational model details the interaction of residues from the conserved p107 SLiM, the B55α groove, and phosphosite presentation. Altogether these data provide key insights into PP2A/B55α mechanisms of substrate recruitment and active site engagement, and also facilitate identification and validation of new substrates, a key step towards understanding PP2A/B55α role in multiple cellular processes.
Data availability
Raw MS data for the the data depicted in Figure 6B are available at MassIVEhttps://massive.ucsd.edu/ProteoSAFe/dataset.jsp?task=9c21e08f6a524d7097e8bd45f0d2f375PXD028612.All NMR chemical shifts (Figure 1E-F) have been deposited in the BioMagResBank (BMRB: 28091).Source code folder (PeptideDock_sourceCode) for Figure 7 is a C# project, including retrieval of peptide structures from PDB and other sources such as PISCES, and calculation of distances and data analyses. https://github.com/DunbrackLab/PP2A_PeptideDock.All other data generated or analysed during this study are included in the manuscript and supporting files. Source Data files have been provided.
Article and author information
Author details
Arminja N Kettenbach
Funding
National Institute of General Medical Sciences (R01 GM117437)
- Xavier Graña
National Cancer Institute (R03 CA216134-01)
- Xavier Graña
WW Smith charitable Trust Award (no reference number)
- Xavier Graña
National Cancer Institute (P30 CA006927)
- Roland L Dunbrack Jr.
- Xavier Graña
National Cancer Institute (U54 CA221704)
- Holly Fowle
- Ziran Zhao
National Institute of General Medical Sciences (R01GM134683)
- Wolfgang Peti
National Institute of Neurological Disorders and Stroke (R01NS091336)
- Wolfgang Peti
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, Fowle et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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PP2A/B55α substrate recruitment as defined by the retinoblastoma-related protein p107
eLife 10:e63181.
https://doi.org/10.7554/eLife.63181
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