PP2A holoenzyme assembly: in cauda venenum (the sting is in the tail)

Janssens, Veerle; Longin, Sari; Goris, Jozef

doi:10.1016/j.tibs.2007.12.004

Cited by 365 publications

(435 citation statements)

References 76 publications

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“…It is highly conserved in eukaryotes, including yeast, Drosophila, mice, and humans (Janssens and Goris, 2001;Janssens et al, 2008). The holoenzyme consists of three subunits: two regulatory subunits A and B and a catalytic subunit C. The regulatory subunit A1 plays an important role in a wide range of physiological processes in both plants (DeLong, 2006) and animals (Janssens et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

Tseng

Briggs

2010

The Plant Cell

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Phototropins (phot) sense blue light through the two N-terminal chromophore binding LOV domains and activate the C-terminal kinase domain. The resulting phototropin autophosphorylation is essential for biological activity. We identified the A1 subunit of Ser/Thr protein phosphatase 2A (PP2A) as interacting with full-length phot2 in yeast and also interacting with phot2 in an in vitro protein binding assay. Phenotypic characterizations of a phot1-5 rcn1-1 (for root curling in n-naphthylphthalamic acid1) double mutant, in which phot2 is the only functional phototropin and PP2A activity is reduced, showed enhanced phototropic sensitivity and enhanced blue light-induced stomatal opening, suggesting that PP2A activity is involved in regulating phot2 function. When treated with cantharidin, a chemical inhibitor of PP2A, the phot1-5 mutant exhibited enhanced phot2-mediated phototropic responses like those of the phot1-5 rcn1-1 double mutant. Immunoblot analysis to examine phot2 endogenous phosphorylation levels and in vitro phosphorylation assays of phot2 extracted from plants during dark recovery from blue light exposure confirmed that phot2 is more slowly dephosphorylated in the reduced PP2A activity background than in the wild-type PP2A background, suggesting that phosphorylated phot2 is a substrate of PP2A activity. While reduced PP2A activity enhanced the activity of phot2, it did not enhance either phot1 dephosphorylation or the activity of phot1 in mediating phototropism or stomatal opening.

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Section: Discussionmentioning

confidence: 99%

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

Tseng

Briggs

2010

The Plant Cell

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“…In general, the PP2A heterotrimeric holoenzyme consists of a catalytic C subunit, a type A regulatory subunit, and a type B regulatory subunit (Terol et al, 2002). Whereas the A regulatory subunits are composed of tandem HEAT repeats that form a hook-like architecture for binding the catalytic and regulatory B subunits, and are hence also known as the scaffold subunits or structural subunits, the type B regulatory subunits of PP2A are diverse (Farkas et al, 2007;Janssens et al, 2008). The catalytic subunits of PP2A (PP2Ac), PP4 (PP4c), and PP6 (PP6c) are most closely related, based on their sequence homology (54 to 64% identities); therefore, they are considered to be PP2A-like phosphatases (Moorhead et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

A PP6-Type Phosphatase Holoenzyme Directly Regulates PIN Phosphorylation and Auxin Efflux in Arabidopsis

et al. 2012

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The directional transport of the phytohormone auxin depends on the phosphorylation status and polar localization of PIN-FORMED (PIN) auxin efflux proteins. While PINIOD (PID) kinase is directly involved in the phosphorylation of PIN proteins, the phosphatase holoenzyme complexes that dephosphorylate PIN proteins remain elusive. Here, we demonstrate that mutations simultaneously disrupting the function of Arabidopsis thaliana FyPP1 (for Phytochrome-associated serine/threonine protein phosphatase1) and FyPP3, two homologous genes encoding the catalytic subunits of protein phosphatase6 (PP6), cause elevated accumulation of phosphorylated PIN proteins, correlating with a basal-to-apical shift in subcellular PIN localization. The changes in PIN polarity result in increased root basipetal auxin transport and severe defects, including shorter roots, fewer lateral roots, defective columella cells, root meristem collapse, abnormal cotyledons (small, cup-shaped, or fused cotyledons), and altered leaf venation. Our molecular, biochemical, and genetic data support the notion that FyPP1/3, SAL (for SAPS DOMAIN-LIKE), and PP2AA proteins (RCN1 [for ROOTS CURL IN NAPHTHYLPHTHALAMIC ACID1] or PP2AA1, PP2AA2, and PP2AA3) physically interact to form a novel PP6-type heterotrimeric holoenzyme complex. We also show that FyPP1/3, SAL, and PP2AA interact with a subset of PIN proteins and that for SAL the strength of the interaction depends on the PIN phosphorylation status. Thus, an Arabidopsis PP6-type phosphatase holoenzyme acts antagonistically with PID to direct auxin transport polarity and plant development by directly regulating PIN phosphorylation. INTRODUCTIONAuxin is a fundamental plant hormone that regulates almost every aspect of plant growth and development, including embryogenesis, organogenesis, apical dominance, tissue regeneration, and tropisms (reviewed in Bennett and Scheres, 2010;Grunewald and Friml, 2010;Peris et al., 2010). Auxin is transported from its sites of biosynthesis to its sites of action by a polarized auxin transport system. Molecular genetic studies in Arabidopsis thaliana have lead to the identification and functional characterization of several key players of the polarized auxin transport system, such as the auxin uptake carriers AUXIN RESISTANT1/LIKE AUX1 (AUX1/ LAX) (Swarup et al., 2008), the auxin efflux carriers, including PIN-FORMED (PIN) family proteins Chen et al., 1998;Müller et al., 1998;Friml et al., 2002;Petrásek et al., 2006), and P-glycoprotein auxin transporters ABCB1 (for ATP BINDING CASSETTE PROTEIN SUBFAMILY B1), ABCB4, and ABCB19 (Terasaka et al., 2005;Bouchard et al., 2006;Blakeslee et al., 2007;Lin and Wang, 2005). PIN proteins are asymmetrically targeted to the plant cell plasma membranes, resulting in distinct polar subcellular localization in a given tissue. For example, PIN1 is localized in the basal (rootward, lower) plasma membrane of stele cells and xylem cells in the vascular system, which is required for long-distance auxin flow from the shoot apex to the root tip Friml e...

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“…17 Protein phosphatase 2A (PP2A) is a heterotrimeric serine/threonine phosphatase comprised of two regulatory subunits (A and B) and a single catalytic subunit (C). [20][21][22][23] B subunits direct substrate specificity and subcellular location and are necessary for PP2A to interact with and dephosphorylate a variety of substrates. [22][23][24] Mammalian PP2A is known to regulate multiple stages of the cell cycle.…”

Section: Introductionmentioning

confidence: 99%

“…[20][21][22][23] B subunits direct substrate specificity and subcellular location and are necessary for PP2A to interact with and dephosphorylate a variety of substrates. [22][23][24] Mammalian PP2A is known to regulate multiple stages of the cell cycle. Cell cycle substrates include the retinoblastoma family of pocket proteins, 25 multiple cell factors required for mitotic exit 26,27 and the shugosin protein involved in sister chromosome segregation.…”

Section: Introductionmentioning

confidence: 99%

PP2A^Cdc55regulates G₁cyclin stability

et al. 2013

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PP2A holoenzyme assembly: in cauda venenum (the sting is in the tail)

Cited by 365 publications

References 76 publications

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

A PP6-Type Phosphatase Holoenzyme Directly Regulates PIN Phosphorylation and Auxin Efflux in Arabidopsis

PP2A^Cdc55regulates G₁cyclin stability

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PP2A holoenzyme assembly: in cauda venenum (the sting is in the tail)

Cited by 365 publications

References 76 publications

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

The Arabidopsis rcn1-1 Mutation Impairs Dephosphorylation of Phot2, Resulting in Enhanced Blue Light Responses

A PP6-Type Phosphatase Holoenzyme Directly Regulates PIN Phosphorylation and Auxin Efflux in Arabidopsis

PP2ACdc55regulates G1cyclin stability

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PP2A^Cdc55regulates G₁cyclin stability