Cloning, expression and structure determination of the major extracellular domain of the PepT1 oligopeptide transporter

No description supplie

Thermal Shift Assay for BRAF mutants for paper: Recognition of BRAF by CDC37 and Re-evaluation of the Activation mechanism for the Class 2 BRAF-L597R Mutant

Data for paper published in Biomolecules June 2022  Raw data for Thermal shift asay of BRAF mutants. Use the LightCycler 480 SW 1.5 software or similar to access the data files. Abstract: The kinome specific co-chaperone, CDC37, is responsible for delivering BRAF to the Hsp90 complex, where it is then translocated to the RAS complex at the plasma membrane for RAS mediated dimerization and subsequent activation. We identify a bipartite interaction between CDC37 and BRAF and delimitate the essential structural elements of CDC37 involved in BRAF recognition. We find an extended and conserved CDC37 motif, 20HPNID---SL--W31, responsible for recognising the C-lobe of BRAF kinase domain, while the C-terminal domain of CDC37 is responsible for the second of the bipartite interaction with BRAF.  We show that dimerization of BRAF, independent of nucleotide binding, can act as a potent signal that prevents CDC37 recognition and discuss the implications of mutations in BRAF and the consequences on signalling in a clinical setting, particularly for class 2 BRAF mutations. </p

ITC data for CDC37-BRAF interactions for paper: Recognition of BRAF by CDC37 and Re-evaluation of the Activation mechanism for the Class 2 BRAF-L597R Mutant

Data for paper published in Biomolecules June 2022  Isothermal Titration Calorimetry results for CDC37-BRAF interactions. dil in the filename donates the heat of dilution. Heats of dilution are in to buffer. Pairs with the same date donate a set of experiments. After the date the interacting partner proteins or small molecule is shown. Use Origin program to access the data files. Abstract: The kinome specific co-chaperone, CDC37, is responsible for delivering BRAF to the Hsp90 complex, where it is then translocated to the RAS complex at the plasma membrane for RAS mediated dimerization and subsequent activation. We identify a bipartite interaction between CDC37 and BRAF and delimitate the essential structural elements of CDC37 involved in BRAF recognition. We find an extended and conserved CDC37 motif, 20HPNID---SL--W31, responsible for recognising the C-lobe of BRAF kinase domain, while the C-terminal domain of CDC37 is responsible for the second of the bipartite interaction with BRAF.  We show that dimerization of BRAF, independent of nucleotide binding, can act as a potent signal that prevents CDC37 recognition and discuss the implications of mutations in BRAF and the consequences on signalling in a clinical setting, particularly for class 2 BRAF mutations. </p

HSP70-HSP90 chaperone networking in protein-misfolding disease

Molecular chaperones and their associated co-chaperones are essential in health and disease as they are key facilitators of protein-folding, quality control and function. In particular, the heat-shock protein (HSP) 70 and HSP90 molecular chaperone networks have been associated with neurodegenerative diseases caused by aberrant protein-folding. The pathogenesis of these disorders usually includes the formation of deposits of misfolded, aggregated protein. HSP70 and HSP90, plus their co-chaperones, have been recognised as potent modulators of misfolded protein toxicity, inclusion formation and cell survival in cellular and animal models of neurodegenerative disease. Moreover, these chaperone machines function not only in folding but also in proteasome-mediated degradation of neurodegenerative disease proteins. This chapter gives an overview of the HSP70 and HSP90 chaperones, and their respective regulatory co-chaperones, and explores how the HSP70 and HSP90 chaperone systems form a larger functional network and its relevance to counteracting neurodegenerative disease associated with misfolded proteins and disruption of proteostasis

ATP binding and hydrolysis are essential to the function of the Hsp90 molecular chaperone in vivo

Hsp90 is an abundant molecular chaperone essential to the establishment of many cellular regulation and signal transduction systems, but remains one of the least well described chaperones. The biochemical mechanism of protein folding by Hsp90 is poorly understood, and the direct involvement of ATP has been particularly contentious. Here we demonstrate in vitro an inherent ATPase activity in both yeast Hsp90 and the Escherichia coli homologue HtpG, which is sensitive to inhibition by the Hsp90-specific antibiotic geldanamycin. Mutations of residues implicated in ATP binding and hydrolysis by structural studies abolish this ATPase activity in vitro and disrupt Hsp90 function in vivo. These results show that Hsp90 is directly ATP dependent in vivo, and suggest an ATP-coupled chaperone cycle for Hsp90-mediated protein folding

ATP binding and hydrolysis are essential to the function of the Hsp90 molecular chaperone in vivo

Hsp90 is an abundant molecular chaperone essential to the establishment of many cellular regulation and signal transduction systems, but remains one of the least well described chaperones. The biochemical mechanism of protein folding by Hsp90 is poorly understood, and the direct involvement of ATP has been particularly contentious. Here we demonstrate in vitro an inherent ATPase activity in both yeast Hsp90 and the Escherichia coli homologue HtpG, which is sensitive to inhibition by the Hsp90-specific antibiotic geldanamycin. Mutations of residues implicated in ATP binding and hydrolysis by structural studies abolish this ATPase activity in vitro and disrupt Hsp90 function in vivo. These results show that Hsp90 is directly ATP dependent in vivo, and suggest an ATP-coupled chaperone cycle for Hsp90-mediated protein folding

[Dataset] The Crystal Structure of the Hsp90-LA1011 Complex and the Mechanism by which LA1011 may Improve the Prognosis of Alzheimer’s Disease

Data for paper published in Biomolecules 2023, 13(7), 105  The data sets are the results for the ITC experiments investigating the interactions between Hsp90, FKBP51 and LA1011. A data set constitutes an ITC file from a heat of dilution or interaction experiment. Data sets are processed by using a pair of experiments represented by a heat of dilution and interaction pair that have the same date stamp at the front of the file name. 'dil' in the filename denotes the heat of dilution. Heats of dilution are into buffer. After the date stamp the interacting partner proteins or small molecule is shown.  The data files require Origin software to access. Abstract    Functional changes in chaperone systems play a major role in the decline of cognition and contribute to neurological pathologies, such as Alzheimer’s disease (AD). While such a decline may occur naturally with age or with stress or trauma, the mechanisms involved have remained elusive. The current models suggest that amyloid-β (Aβ) plaque formation leads to the hyperphosphorylation of tau by a Hsp90-dependent process that triggers tau neurofibrillary tangle formation and neurotoxicity. Several co-chaperones of Hsp90 can influence the phosphorylation of tau, including FKBP51, FKBP52 and PP5. In particular, elevated levels of FKBP51 occur with age and stress and are further elevated in AD. Recently, the dihydropyridine LA1011 was shown to reduce tau pathology and amyloid plaque formation in transgenic AD mice, probably through its interaction with Hsp90, although the precise mode of action is currently unknown. Here, we present a co-crystal structure of LA1011 in complex with a fragment of Hsp90. We show that LA1011 can disrupt the binding of FKBP51, which might help to rebalance the Hsp90-FKBP51 chaperone machinery and provide a favourable prognosis towards AD. However, without direct evidence, we cannot completely rule out effects on other Hsp90-co-chaprone complexes and the mechanisms they are involved in, including effects on Hsp90 client proteins. Nonetheless, it is highly significant that LA1011 showed promise in our previous AD mouse models, as AD is generally a disease affecting older patients, where slowing of disease progression could result in AD no longer being life limiting. The clinical value of LA1011 and its possible derivatives thereof remains to be seen.</p

The crystal structure of the Hsp90-LA1011 complex and the mechanism by which LA1011 may improve the prognosis of Alzheimer’s disease

Functional changes in chaperone systems play a major role in the decline of cognition and contribute to neurological pathologies, such as Alzheimer’s disease (AD). While such a decline may occur naturally with age or with stress or trauma, the mechanisms involved have remained elusive. The current models suggest that amyloid-β (Aβ) plaque formation leads to the hyperphosphorylation of tau by a Hsp90-dependent process that triggers tau neurofibrillary tangle formation and neurotoxicity. Several co-chaperones of Hsp90 can influence the phosphorylation of tau, including FKBP51, FKBP52 and PP5. In particular, elevated levels of FKBP51 occur with age and stress and are further elevated in AD. Recently, the dihydropyridine LA1011 was shown to reduce tau pathology and amyloid plaque formation in transgenic AD mice, probably through its interaction with Hsp90, although the precise mode of action is currently unknown. Here, we present a co-crystal structure of LA1011 in complex with a fragment of Hsp90. We show that LA1011 can disrupt the binding of FKBP51, which might help to rebalance the Hsp90-FKBP51 chaperone machinery and provide a favourable prognosis towards AD. However, without direct evidence, we cannot completely rule out effects on other Hsp90-co-chaprone complexes and the mechanisms they are involved in, including effects on Hsp90 client proteins. Nonetheless, it is highly significant that LA1011 showed promise in our previous AD mouse models, as AD is generally a disease affecting older patients, where slowing of disease progression could result in AD no longer being life limiting. The clinical value of LA1011 and its possible derivatives thereof remains to be seen.</p

Activation of autophagy depends on Atg1/Ulk1-mediated phosphorylation and inhibition of the Hsp90 chaperone machinery

Cellular homeostasis relies on both the chaperoning of proteins and the intracellular degradation system that delivers cytoplasmic constituents to the lysosome, a process known as autophagy. The crosstalk between these processes and their underlying regulatory mechanisms is poorly understood. Here, we show that the molecular chaperone heat shock protein 90 (Hsp90) forms a complex with the autophagy-initiating kinase Atg1 (yeast)/Ulk1 (mammalian), which suppresses its kinase activity. Conversely, environmental cues lead to Atg1/Ulk1-mediated phosphorylation of a conserved serine in the amino domain of Hsp90, inhibiting its ATPase activity and altering the chaperone dynamics. These events impact a conformotypic peptide adjacent to the activation and catalytic loop of Atg1/Ulk1. Finally, Atg1/Ulk1-mediated phosphorylation of Hsp90 leads to dissociation of the Hsp90:Atg1/Ulk1 complex and activation of Atg1/Ulk1, which is essential for initiation of autophagy. Our work indicates a reciprocal regulatory mechanism between the chaperone Hsp90 and the autophagy kinase Atg1/Ulk1 and consequent maintenance of cellular proteostasis.</p

[Erratum] Activation of autophagy depends on Atg1/Ulk1-mediated phosphorylation and inhibition of the Hsp90 chaperone machinery (Cell Reports (2023) 42(7), (S2211124723008185), (10.1016/j.celrep.2023.112807))

(Cell Reports 42, 112807; July 25, 2023) In the originally published version of this article, the image for the strain ΔAtg1 S25A in Figure 5D was a duplicate of strain Atg1 with S25A in Figure 5B. The correct image for Figure 5D is now present online and shown below. The authors regret this error. [Formula presented] [Formula presented]</p