<i>cis</i>‐Effect of DnaJ on DnaK in ternary complexes with chimeric DnaK/DnaJ‐binding peptides

Han, Wanjiang; Christen, Philipp

doi:10.1016/s0014-5793(04)00290-x

Cited by 41 publications

(43 citation statements)

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“…4A) (i.e. by the same factor as found earlier at 25°C) (12). In contrast, RCMLA and pp, which are substrates that do not form ternary complexes and consequently do not elicit the cis-effect of DnaJ, only barely stimulated the rate of ATP hydrolysis at all temperatures tested.…”

Section: Dnaj-controlled T 3 R Conversion-supporting

confidence: 77%

“…However, no experimental evidence has been reported as yet for this substrate transfer. A plausible mechanism of the targeting action of DnaJ is provided by the concept of a cis-effect of DnaJ on DnaK in ternary (ATP⅐DnaK)⅐substrate⅐DnaJ complexes (11,12); the simultaneous binding of DnaK and DnaJ to one and the same polypeptide chain results in a higher effective concentration of DnaJ.During heat shock and other cellular stress, the expression level of DnaK and its co-chaperones is enhanced to cope with the rising amount of misfolded and aggregation-prone proteins (for a recent review, see Ref. 16).…”

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confidence: 99%

“…Protein substrates, such as firefly luciferase, 32 (9), denatured rhodanese, or RepA (11,12), accelerate the DnaJ-stimulated hydrolysis of DnaK-bound ATP by 1-2 orders of magnitude. DnaJ not only stimulates the ATPase activity of DnaK but also associates with unfolded proteins and prevents protein aggregation (13)(14)(15).…”

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confidence: 99%

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confidence: 99%

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Tuning of DnaK Chaperone Action by Nonnative Protein Sensor DnaJ and Thermosensor GrpE

Siegenthaler

Christen

2006

Journal of Biological Chemistry

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DnaK, an Hsp70 molecular chaperone, processes its substrates in an ATP-driven cycle, which is controlled by the cochaperones DnaJ and GrpE. The kinetic analysis of substrate binding and release has as yet been limited to fluorescence-labeled peptides. Here, we report a comprehensive kinetic analysis of the chaperone action with protein substrates. The kinetic partitioning of the (ATP⅐DnaK)⅐substrate complexes between dissociation and conversion into stable (ADP⅐DnaK)⅐substrate complexes is determined by DnaJ. In the case of substrates that allow the formation of ternary (ATP⅐DnaK)⅐substrate⅐DnaJ complexes, the cis-effect of DnaJ markedly accelerates ATP hydrolysis. This triage mechanism efficiently selects from the (ATP⅐DnaK)⅐substrate complexes those to be processed in the chaperone cycle; at 45°C, the fraction of protein complexes fed into the cycle is 20 times higher than that of peptide complexes. The thermosensor effect of the ADP/ATP exchange factor GrpE retards the release of substrate from the cycle at higher temperatures; the fraction of total DnaK in stable (ADP⅐DnaK)⅐substrate complexes is 2 times higher at 45°C than at 25°C. Monitoring the cellular situation by DnaJ as nonnative protein sensor and GrpE as thermosensor thus directly adapts the operational mode of the DnaK system to heat shock conditions. Molecular chaperones of the 70-kDa heat shock protein (Hsp70) 2 family assist folding and refolding of nascent and stress-denatured proteins, assembly and disassembly of protein complexes, and translocation of polypeptide chains across membranes. All of these activities appear to rely on the transient interaction of Hsp70 with short hydrophobic segments of their protein substrates. The cycle of substrate binding and release is driven by the hydrolysis of ATP. DnaK, an Hsp70 homolog in Escherichia coli, consists of a 44-kDa NH 2 -terminal ATPase domain (1, 2) and a 25-kDa COOH-terminal substratebinding domain (3). Hydrolysis of DnaK-bound ATP and ADP/ ATP exchange control the functional properties of the substrate-binding domain (4). ATP-liganded DnaK (T-state DnaK) exhibits low affinity for substrates and fast rates of binding and release, whereas ADP-liganded (R-state) DnaK is characterized by high substrate affinity and slow kinetics (5, 6). DnaK acts in concert with two co-chaperones (Fig. 1). DnaJ, an Hsp40 homolog, stimulates the hydrolysis of ATP and thus promotes the formation of high affinity (ADP⅐DnaK)⅐substrate complexes, whereas GrpE facilitates the exchange of ADP for ATP and thus triggers the release of substrate from the cycle (7-9).Fluorescence-labeled peptides have allowed the kinetic analysis of the formation of DnaK⅐peptide complexes (6). With protein substrates, however, no kinetic data have been reported to date, DnaK⅐protein complexes having solely been examined by size exclusion chromatography (5), by nondenaturing gel electrophoresis (2), and by measuring fluorescence anisotropy under steady-state conditions (10).A major question in the field of molecular chaperones is how targe...

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Section: Dnaj-controlled T 3 R Conversion-supporting

confidence: 77%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Tuning of DnaK Chaperone Action by Nonnative Protein Sensor DnaJ and Thermosensor GrpE

Siegenthaler

Christen

2006

Journal of Biological Chemistry

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“…DnaK is the bacterial representative of the Hsp70 family and, in collaboration with GrpE (nucleotide exchange factor) and DnaJ (Hsp40), prevents protein aggregation and productively solubilizes protein aggregates either alone or together with ClpB (the Hsp100 representative in Escherichia coli) (6). DnaJ is involved in the transfer of substrates to DnaK (7)(8)(9)(10)(11) and, together with GrpE, in controlling the time the chaperone spends in the low affinity and high affinity states for substrate proteins (5). These DnaJ roles have been found essential for almost all chaperone activities of Hsp70 proteins (12,13).…”

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confidence: 99%

DnaJ Recruits DnaK to Protein Aggregates

Acebrón¹,

Fernández‐Sáiz²,

Taneva³

et al. 2008

Journal of Biological Chemistry

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Thermal stress might lead to protein aggregation in the cell. Reactivation of protein aggregates depends on Hsp100 and Hsp70 chaperones. We focus in this study on the ability of DnaK, the bacterial representative of the Hsp70 family, to interact with different aggregated model substrates. Our data indicate that DnaK binding to large protein aggregates is mediated by DnaJ, and therefore it depends on its affinity for the cochaperone. Mutations in the structural region of DnaK known as the "latch" decrease the affinity of the chaperone for DnaJ, resulting in a defective activity as protein aggregate-removing agent. As expected, the chaperone activity is recovered when DnaJ concentration is raised to overcome the lower affinity of the mutant for the cochaperone, suggesting that a minimum number of aggregate-bound DnaK molecules is necessary for its efficient reactivation. Our results provide the first experimental evidence of DnaJ-mediated recruiting of ATP-DnaK molecules to the aggregate surface.

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Plant Molecular Chaperones: Structural Organization and their Roles in Abiotic Stress Tolerance

Singh

Gupta

Prasad

2019

Molecular Plant Abiotic Stress

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cis‐Effect of DnaJ on DnaK in ternary complexes with chimeric DnaK/DnaJ‐binding peptides

Cited by 41 publications

References 35 publications

Tuning of DnaK Chaperone Action by Nonnative Protein Sensor DnaJ and Thermosensor GrpE

Tuning of DnaK Chaperone Action by Nonnative Protein Sensor DnaJ and Thermosensor GrpE

DnaJ Recruits DnaK to Protein Aggregates

Plant Molecular Chaperones: Structural Organization and their Roles in Abiotic Stress Tolerance

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