A Conserved Motif Provides Binding Specificity to the PP2A-B56 Phosphatase

Hertz, Emil Peter Thrane; Kruse, Thomas; Davey, Norman E.; López-Méndez, Blanca; Sigurðsson, Jón Otti; Montoya, Guillermo; Olsen, Jesper V.; Nilsson, Jakob

doi:10.1016/j.molcel.2016.06.024

Cited by 254 publications

(396 citation statements)

References 28 publications

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“…This is complementary to a sequence conservation and computational prediction approach that was recently used to identify LSPI sequences (Hertz et al, 2016). By using these structures as a ‘molecular ruler’ to define the LSPIxE SLiM, we focus on identifying the most stringent B56 interactors.…”

Section: Resultsmentioning

confidence: 99%

Expanding the PP2A Interactome by Defining a B56-Specific SLiM

et al. 2016

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SUMMARY Specific interactions between proteins govern essential physiological processes including signaling. Many enzymes, especially the family of serine/threonine phosphatases (PSPs: PP1, PP2A and PP2B/calcineurin/CN), recruit substrates and regulatory proteins by binding Short Linear Motifs (SLiMs), short sequences found within intrinsically disordered regions (IDRs) that mediate specific protein:protein interactions. While tremendous progress had been made in identifying where and how SLiMs bind PSPs, especially PP1 and CN, essentially nothing is known about how SLiMs bind PP2A, a validated cancer drug target. Here we describe three structures of PP2A:SLiM interaction (B56: pS-RepoMan, B56:pS-BubR1 and B56:pSpS-BubR1), show that this PP2A-specific SLiM is defined as LSPIxE and then use this data to discover scores of likely PP2A regulators and substrates. Together, these data not only provide a powerful approach for dissecting PP2A interaction networks in cells but also for targeting PP2A diseases, such as cancer.

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Section: Resultsmentioning

confidence: 99%

Expanding the PP2A Interactome by Defining a B56-Specific SLiM

et al. 2016

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“…The binding affinity (or, more specifically, the dissociation rate) determines the residence time of a substrate on the APC/C, and, together with the enzyme catalytic rate, determines the number of ubiquitins attached per binding event (processivity). Several studies of other motif-binding domain families indicate that degeneracy of motif-binding pocket specificity permits peptides recognized by that pocket to exhibit a wide range of affinities (Roy et al, 2007; Hertz et al, 2016). In the case of the APC/C, the affinity of an individual degron has not been directly determined.…”

Section: Substrate Ordering By the Apc/cmentioning

confidence: 99%

“…Drawing analogies to motifs with similar properties (e.g. the PP2A B56 LxxIxE docking motif, which physicochemically resembles the D box) (Hertz et al, 2016), it is likely that single APC/C degrons bind with dissociation constants (K D ) in the low μM range.…”

Section: Substrate Ordering By the Apc/cmentioning

confidence: 99%

Building a Regulatory Network with Short Linear Sequence Motifs: Lessons from the Degrons of the Anaphase-Promoting Complex

2016

Self Cite

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Summary The anaphase-promoting complex or cyclosome (APC/C) is a ubiquitin ligase that polyubiquitinates specific substrates at precise times in the cell cycle, thereby triggering the events of late mitosis in a strict order. The robust substrate specificity of the APC/C prevents the potentially deleterious degradation of non-APC/C substrates, and also averts the cell cycle errors and genomic instability that could result from mistimed degradation of APC/C targets. The APC/C recognizes short linear sequence motifs, or degrons, on its substrates. The specific and timely modification and degradation of APC/C substrates is likely to be modulated by variations in degron sequence and context. We discuss the extensive affinity, specificity and selectivity determinants encoded in APC/C degrons, and we describe some of the extrinsic mechanisms that control APC/C-substrate recognition. As an archetype for protein motif-driven regulation of cell function, the APC/C-substrate interaction provides insights into the general properties of post-translational regulatory systems.

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“…Crucially, the activity of PP2A-B55d fluctuates during the cell cycle, via the PP2A-B55d/ENSA/Greatwall pathway, and is high in interphase and low in mitosis [18][19][20]. More recent work suggests that PP2A-B56 achieves its functional specificity by binding to a LxxIxE short linear motif (SLiM) in which Glu (E) at position 6 is crucial, but position 1 (Leu) and position 4 (Ile) can be replaced by other hydrophobic residues, and phosphorylation or the enrichment of acidic residues within and downstream from the motif can increase PP2A-B56 binding [25][26][27]. In contrast, PP2A-B56 has been shown to be active during mitosis.…”

Section: Introductionmentioning

confidence: 99%

PP2A‐B56 binds to Apc1 and promotes Cdc20 association with the APC/C ubiquitin ligase in mitosis

Fujimitsu

Yamano

2019

EMBO Reports

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Cell cycle progression and genome stability are regulated by a ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C). Cyclin-dependent kinase 1 (Cdk1) has long been implicated in APC/ C activation; however, the molecular mechanisms of governing this process in vivo are largely unknown. Recently, a Cdk1-dependent phosphorylation relay within Apc3-Apc1 subunits has been shown to alleviate Apc1-mediated auto-inhibition by which a mitotic APC/ C co-activator Cdc20 binds to and activates the APC/C. However, the underlying mechanism for dephosphorylation of Cdc20 and APC/C remains elusive. Here, we show that a disordered loop domain of Apc1 (Apc1-loop 500 ) directly binds the B56 regulatory subunit of protein phosphatase 2A (PP2A) and stimulates Cdc20 loading to the APC/C. Using the APC/C reconstitution system in Xenopus egg extracts, we demonstrate that mutations in Apc1loop 500 that abolish B56 binding decrease Cdc20 loading and APC/ C-dependent ubiquitylation. Conversely, a non-phosphorylatable mutant Cdc20 can efficiently bind the APC/C even when PP2A-B56 binding is impeded. Furthermore, PP2A-B56 preferentially dephosphorylates Cdc20 over the Apc1 inhibitory domain. These results indicate that Apc1-loop 500 plays a role in dephosphorylating Cdc20, promoting APC/C-Cdc20 complex formation in mitosis.

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A Conserved Motif Provides Binding Specificity to the PP2A-B56 Phosphatase

Cited by 254 publications

References 28 publications

Expanding the PP2A Interactome by Defining a B56-Specific SLiM

Expanding the PP2A Interactome by Defining a B56-Specific SLiM

Building a Regulatory Network with Short Linear Sequence Motifs: Lessons from the Degrons of the Anaphase-Promoting Complex

PP2A‐B56 binds to Apc1 and promotes Cdc20 association with the APC/C ubiquitin ligase in mitosis

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