PP2A/B55α substrate recruitment as defined by the retinoblastoma-related protein p107

eLife

Rebecca Page¹  Wolfgang Peti²  Brennan C McEwan³  Arminja N Kettenbach³  Xinru Wang⁴  Roland L Dunbrack⁵  Qifang Xu⁵  Xavier Graña⁶  Ziran Zhao⁶  Jason S Wasserman⁶  Diba Atar⁶  Mary Adeyemi⁶  Holly Fowle⁶  Alison N Kurimchak⁶  Felicity Feiser⁶ 

[1]Department Cell Biology, UConn Health, Farmington, United States

[2]Department Molecular Biology and Biophysics, UConn Health, Farmington, United States

[3]Department of Biochemistry and Cell Biology, Hitchcock Medical Center at Dartmouth, Lebanon, United States

[4]Department of Chemistry and Biochemistry, University of Arizona, Tucson, United States

[5]Fels Institute for Cancer Research and Molecular Biology, Temple University Lewis Katz School of Medicine, Philadelphia, United States

[6]Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, United States

关键词: serine-threonine phosphatase;    PP2A;    phosphorylation;    enzyme;    p107;    TAU;    E. coli;    Human;   

DOI  :  10.7554/eLife.63181

来源: eLife Sciences Publications, Ltd

【 摘 要 】

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’s mechanisms of substrate recruitment and active site engagement, and also facilitate identification and validation of new substrates, a key step towards understanding PP2A/B55α’s role in multiple cellular processes.

【 授权许可】

CC BY