The Crystal Structure of the Carboxy-Terminal Dimerization Domain of htpG, the Escherichia coli Hsp90, Reveals a Potential Substrate Binding Site

Harris, S.F.; Shiau, Andrew K.; Agard, David A.

doi:10.1016/j.str.2004.03.020

Cited by 173 publications

(166 citation statements)

References 57 publications

(6 reference statements)

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“…The advent of the C-terminal crystal structure provided further evidence for the antiparallel dimeric architecture of Hsp90 that had been previously predicted by electron microscopy [20][21][22]. C-terminal truncations of Hsp90 abolish its ability to hydrolyze ATP, indicating that its dimeric nature is essential for its activity [13].…”

mentioning

confidence: 67%

Hsp90—From signal transduction to cell transformation

Brown

Zhu

Schmidt

et al. 2007

Biochemical and Biophysical Research Communications

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The molecular chaperone, Hsp90, facilitates the maturation and/or activation of over 100 'client proteins' involved in signal transduction and transcriptional regulation. Largely an enigma among the families of heat shock proteins, Hsp90 is central to processes broadly ranging from cell cycle regulation to cellular transformation. Here we review the contemporary body of knowledge regarding the biochemical mechanisms of Hsp90 and update the most current paradigms defining its involvement in both normal and pathological cell physiology. KeywordsHsp90; heat shock protein; molecular chaperone; ATPase; genetic capacitor Hsp90 defines a family of molecular chaperones that are highly conserved from prokaryotes to eukaryotes [1][2][3][4][5]. Nonessential for normal growth in most bacteria, Hsp90 is abundantly expressed in higher eukaryotes where it has been shown to be necessary for viability [6,7]. It functions as a homodimer that associates with co-chaperones to catalyze the maturation and/ or activation of over 100 substrate proteins that are known to be involved in cell regulatory pathways [5]. These 'client proteins' include protein kinases, nuclear hormone receptors, transcription factors, and an array of other essential proteins [8]. While much is known regarding the ATPase-driven conformational cycling of Hsp90, the precise physical effects imparted by this chaperone that serve to activate its substrates are still poorly understood [5]. Hsp90 architectureThree highly conserved domains comprise the structure of Hsp90. These include the N-terminal domain, responsible for ATP-binding, a proteolytically resistant core domain, and the Cterminal domain that facilitates homodimerization (Fig. 1a) [9]. In eukaryotes, a more variable charged region links the N-terminal domain to the core domain. The length and composition of this linker region is highly divergent among organisms [10]. As no atomic resolution structure for full-length Hsp90 is yet available, the most thorough structural analyses for Hsp90, to date, have been based on crystallographic studies of its individual domains.A mechanistic understanding of Hsp90 was nebulous until partial sequence homology was recognized between its N-terminal domain and two types of ATP-dependent proteins. These

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mentioning

confidence: 67%

Hsp90—From signal transduction to cell transformation

Brown

Zhu

Schmidt

et al. 2007

Biochemical and Biophysical Research Communications

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“…Human Hsp90␣ C-terminal domain structure model was built with the SWISS-MODEL protein homologymodeling server (10) (http:͞͞swissmodel.expasy.org) by using as a template the eight chains of the PDB ID code 1sf8, corresponding to the structure of the Escherichia coli HtpG Cterminal domain (11). Ribbon representation was obtained with the MOLMOL program (12).…”

Section: Methodsmentioning

confidence: 99%

“…We have built a model of the Hsp90␣ region spanning the mapped cysteines (Fig. 2C) based on the recently published structure of its E. coli homolog, htpG (11). In this model, the two contiguous cysteines are arranged in a ␤-chain, with the Cys 596 side chain oriented toward the domain inside, whereas Cys 597 is clearly exposed to the protein surface.…”

Section: Identification Of S-nitrosylated Cysteine Residue(s) Of Hsp9mentioning

confidence: 99%

S-nitrosylation of Hsp90 promotes the inhibition of its ATPase and endothelial nitric oxide synthase regulatory activities

Martínez‐Ruiz

Villanueva²,

Orduña³

et al. 2005

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

279

221

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Nitric oxide is implicated in a variety of signaling pathways in different systems, notably in endothelial cells. Some of its effects can be exerted through covalent modifications of proteins and, among these modifications, increasing attention is being paid to S-nitrosylation as a signaling mechanism. In this work, we show by a variety of methods (ozone chemiluminescence, biotin switch, and mass spectrometry) that the molecular chaperone Hsp90 is a target of S-nitrosylation and identify a susceptible cysteine residue in the region of the C-terminal domain that interacts with endothelial nitric oxide synthase (eNOS). We also show that the modification occurs in endothelial cells when they are treated with S-nitroso-L-cysteine and when they are exposed to eNOS activators. Hsp90 ATPase activity and its positive effect on eNOS activity are both inhibited by S-nitrosylation. Together, these data suggest that S-nitrosylation may functionally regulate the general activities of Hsp90 and provide a feedback mechanism for limiting eNOS activation.atherosclerosis ͉ nitrosation ͉ vascular wall ͉ chaperone R ecent years have witnessed an increasing interest in the roles of nitric oxide (NO) in signal transduction pathways other than its activation of the cGMP pathway. Many of these roles rely on NO's ability to alter protein function through posttranslational modifications. Among these modifications, S-nitrosylation has emerged as a potential and fundamental regulator of protein function. S-nitrosylation is a covalent modification of thiol groups by formation of a thionitrite (-S-NϭO) group, facilitated by the formation of higher nitrogen oxides (1, 2). To date, several dozens of proteins have been shown to become S-nitrosylated and, in many cases, this modification was accompanied by altered function (see table S1 of ref. 1 for review).Nitric oxide, synthesized in the endothelium by endothelial nitric oxide synthase (eNOS), plays crucial roles in the vascular wall, including the maintenance of vascular tone. The possibility that NO might modify eNOS, or elements of the complex system involved in its activation, is an attractive hypothesis, suggesting a potential autoregulatory feedback mechanism. The eNOS enzyme is regulated by several posttranslational modifications including myristoylation, palmitoylation, and phosphorylation (3). This enzyme is also tightly regulated by specific interactions with inhibitory proteins such as caveolin-1 and by positive modulation by the scaffolding protein Hsp90. These interactions have been described in detail, and a relatively complete picture is beginning to emerge (4).We have previously used a proteomic approach to identify several proteins that were S-nitrosylated after exposure of vascular endothelial cells to the physiological nitrosothiol, Snitroso-L-cysteine (CSNO) (5). Further work led to the identification of Hsp90 as a protein susceptible to S-nitrosylation. This chaperone protein, known for its functions in protein folding, degradation, and scaffolding, has attracted renewed ...

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“…This causes the displacement of ATP and functional arrest of the Hsp90 chaperone cycle (Stebbins et al, 1997;Whitesell and Lindquist, 2005). The middle domain is followed by a carboxy-terminal domain (CTD) which mediates dimerization and is less conserved in sequence (Harris et al, 2004;Minami et al, 1994). The five C-terminal residues (MEEVD motif) form a highly conserved TPR domain binding site that allows Hsp90 to interact with a number of co-chaperones containing TPR domains (Pearl and Prodromou, 2006;Young et al, 1998).…”

Section: Ii41122 the Hsp90 Chaperone Systemmentioning

confidence: 99%