Threonine 22 Phosphorylation Attenuates Hsp90 Interaction with Cochaperones and Affects Its Chaperone Activity

Mollapour, Mehdi; Tsutsumi, Shinji; Truman, Andrew W.; Xu, Wanping; Vaughan, Cara K.; Beebe, Kristin; Konstantinova, Anna; Vourganti, Srinivas; Panaretou, Barry; Piper, Peter W.; Trepel, Jane B.; Prodromou, Chrisostomos; Pearl, Laurence H.; Neckers, Len

doi:10.1016/j.molcel.2011.02.011

Cited by 149 publications

(177 citation statements)

References 37 publications

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“…Serine/threonine phosphorylation of Hsp90 itself is, in general, found to result in reduced affinity with clients (31)(32)(33). Client kinase release is also triggered by tyrosine phosphorylation of Cdc37 on Y298 by the Src family kinase YES, and tyrosine phosphorylation of Hsp90 on Y627 dissociates Cdk4 (21).…”

Section: Discussionmentioning

confidence: 99%

Structural and functional basis of protein phosphatase 5 substrate specificity

Oberoi

Dunn

Woodford

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The serine/threonine phosphatase protein phosphatase 5 (PP5) regulates hormone-and stress-induced cellular signaling by association with the molecular chaperone heat shock protein 90 (Hsp90). PP5-mediated dephosphorylation of the cochaperone Cdc37 is essential for activation of Hsp90-dependent kinases. However, the details of this mechanism remain unknown. We determined the crystal structure of a Cdc37 phosphomimetic peptide bound to the catalytic domain of PP5. The structure reveals PP5 utilization of conserved elements of phosphoprotein phosphatase (PPP) structure to bind substrate and provides a template for many PPP-substrate interactions. Our data show that, despite a highly conserved structure, elements of substrate specificity are determined within the phosphatase catalytic domain itself. Structure-based mutations in vivo reveal that PP5-mediated dephosphorylation is required for kinase and steroid hormone receptor release from the chaperone complex. Finally, our data show that hyper-or hypoactivity of PP5 mutants increases Hsp90 binding to its inhibitor, suggesting a mechanism to enhance the efficacy of Hsp90 inhibitors by regulation of PP5 activity in tumors.Hsp90 | PP5 | Cdc37 | chaperone | phosphatase P rotein phosphatase 5 (PP5) has pleiotropic roles in cellular signaling, including DNA damage repair, proliferation of breast cancer cells, circadian cycling, response to cytotoxic stresses, Rac-dependent potassium ion channel activity, and activation of steroid hormone receptors [e.g., glucocorticoid receptor (GR) and estrogen receptor] (1, 2). It is a member of the phosphoprotein phosphatase (PPP) family of serine/threonine phosphatases, which has members that share a highly conserved catalytic core and catalytic mechanism dependent on two metal ions, commonly Mn 2+ . Most PPP family members exhibit high, nonspecific phosphatase activity. Specificity is provided by a large cohort of regulatory and other interacting proteins that function to inhibit basal activity and recruit substrates, thereby finely tuning the enzymes (3). This combinatorial approach enables a small number of catalytic subunits to have the breadth of specificity equivalent to that seen in kinases, which are greater in number by an order of magnitude. Structures of complexes between regulatory and catalytic domains have illuminated the importance of regulatory subunits in facilitating substrate recruitment (3). However, to date, there is no structural information describing how a substrate binds at the active site of a PPP; therefore, a central question remains of how local interactions between the substrate and the catalytic domain contribute to the molecular basis of dephosphorylation.PP5 is unique among the PPP family because it has a low basal activity caused by an autoinhibitory N-terminal tetratricopeptide (TPR) domain (4). Its activity is promoted by a number of cellular factors, including fatty acids and the molecular chaperone heat shock protein 90 (Hsp90) (5), both of which release autoinhibition by interacting with the TPR...

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Section: Discussionmentioning

confidence: 99%

Structural and functional basis of protein phosphatase 5 substrate specificity

Oberoi

Dunn

Woodford

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Recent reports have identified key phosphorylation sites on HSP90 that affect its ability to interact with a select subset of cochaperones, and consequently, client proteins (52,53). These findings clearly reveal that HSP90 abundance alone is not the sole determinant of its activity, because the phosphorylation of HSP90 by the yeast cell cycle-regulated kinase Swe1 implies a time-or development-specific window of HSP90 activation (53).…”

Section: Hsp90 Is Required For Proper Period Regulation Of the Circadmentioning

confidence: 96%

HSP90 functions in the circadian clock through stabilization of the client F-box protein ZEITLUPE

Kim

Fujiwara

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

111

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The autoregulatory loops of the circadian clock consist of feedback regulation of transcription/translation circuits but also require finely coordinated cytoplasmic and nuclear proteostasis. Although protein degradation is important to establish steady-state levels, maturation into their active conformation also factors into protein homeostasis. HSP90 facilitates the maturation of a wide range of client proteins, and studies in metazoan clocks implicate HSP90 as an integrator of input or output. Here we show that the Arabidopsis circadian clock-associated F-box protein ZEITLUPE (ZTL) is a unique client for cytoplasmic HSP90. The HSP90-specific inhibitor geldanamycin and RNAi-mediated depletion of cytoplasmic HSP90 reduces levels of ZTL and lengthens circadian period, consistent with ztl loss-of-function alleles. Transient transfection of artificial microRNA targeting cytoplasmic HSP90 genes similarly lengthens period. Proteolytic targets of SCF ZTL , TOC1 and PRR5, are stabilized in geldanamycin-treated seedlings, whereas the levels of closely related clock proteins, PRR3 and PRR7, are unchanged. An in vitro holdase assay, typically used to demonstrate chaperone activity, shows that ZTL can be effectively bound, and aggregation prevented, by HSP90. GIGANTEA, a unique stabilizer of ZTL, may act in the same pathway as HSP90, possibly linking these two proteins to a similar mechanism. Our findings establish maturation of ZTL by HSP90 as essential for proper function of the Arabidopsis circadian clock. Unlike metazoan systems, HSP90 functions here within the core oscillator. Additionally, F-box proteins as clients may place HSP90 in a unique and more central role in proteostasis.protein maturation | proteolysis T he circadian clock system sustains 24-h rhythmicity at the molecular and physiological level in most organisms that have been examined. A key function of the clock is to appropriately phase many essential physiological and biochemical processes in anticipation of the light/dark and temperature changes that occur each day. In both plants and animals impaired operation of the circadian clock results in reduced function and fitness, leading to increased propensity for disease and poor growth and reproductive success (1-5).The underlying basis of circadian clocks involves autoregulatory feedback loops that consist of positive activating and negative repressing elements that control gene transcription and protein activity and localization (6-8). The Arabidopsis circadian system consists of at least three interlocked feedback loops. Although more than 20 different genes are associated with circadian timing in plants, only a small subset has been incorporated into coherent interaction schemes (9, 10). Current models are based largely on transcriptional relationships, but increasingly posttranslational processes, such as regulated proteolysis, have been found to be critical for proper clock function (11-17). In Arabidopsis, the F-box protein ZEITLUPE (ZTL) is an eveningphased clock component responsible for the pro...

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“…It has been known for some time that Hsp90 is phosphorylated in mammalian cells 62,63 . Similarly, phosphorylation of S. cerevisiae Hsp90 is thought to influence its activity and hence the rate of maturation of specific client proteins 64,65 . Yeast Hsp90 is phosphorylated by Swe1 and casein kinase 2 (CK2), and is dephosphorylated by Ppt1 61,[64][65][66] .…”

Section: Post-translational Modification Of Hsp90mentioning

confidence: 99%

Fungal Hsp90: a biological transistor that tunes cellular outputs to thermal inputs

et al. 2012

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Preface Hsp90 is an essential, abundant, and ubiquitous eukaryotic chaperone that has crucial roles in protein folding and modulates the activities of key regulators. The fungal Hsp90 interactome, which includes numerous client proteins such as receptors, protein kinases and transcription factors, displays a surprisingly high degree of plasticity that depends on environmental conditions. Furthermore, although Hsp90 levels increase following environmental challenges, Hsp90 activity is tightly controlled via post-translational regulation and an autoregulatory loop involving the heat shock transcription factor, Hsf1. In this review, we discuss the roles and regulation of Hsp90. We propose that Hsp90 acts as a biological transistor that modulates the activity of fungal signalling networks in response to environmental cues via this Hsf1-Hsp90 autoregulatory loop.

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Threonine 22 Phosphorylation Attenuates Hsp90 Interaction with Cochaperones and Affects Its Chaperone Activity

Cited by 149 publications

References 37 publications

Structural and functional basis of protein phosphatase 5 substrate specificity

Structural and functional basis of protein phosphatase 5 substrate specificity

HSP90 functions in the circadian clock through stabilization of the client F-box protein ZEITLUPE

Fungal Hsp90: a biological transistor that tunes cellular outputs to thermal inputs

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