The Importance of a Mobile Loop in Regulating Chaperonin/ Co-chaperonin Interaction

Richardson, Alexandra J.; Schwager, Françoise; Landry, Samuel J.; Georgopoulos, Costa

doi:10.1074/jbc.m008628200

Cited by 64 publications

(72 citation statements)

References 58 publications

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“…Presence of the respective variations and absence of mutagenesisinduced PCR errors was established by sequencing and subcloning. The resulting vectors were used in the genetic complementation assay described previously (Hansen et al 2002;Richardson et al 2001).…”

Section: Analysis Of Missense Variationsmentioning

confidence: 99%

Single-nucleotide variations in the genes encoding the mitochondrial Hsp60/Hsp10 chaperone system and their disease-causing potential

Bross

Hansen

et al. 2006

J Hum Genet

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Molecular chaperones assist protein folding, and variations in their encoding genes may be disease-causing in themselves or influence the phenotypic expression of disease-associated or susceptibility-conferring variations in many different genes. We have screened three candidate patient groups for variations in the HSPD1 and HSPE1 genes encoding the mitochondrial Hsp60/Hsp10 chaperone complex: two patients with multiple mitochondrial enzyme deficiency, 61 sudden infant death syndrome cases (MIM: #272120), and 60 patients presenting with ethylmalonic aciduria carrying non-synonymous susceptibility variations in the ACADS gene (MIM: *606885 and #201470). Besides previously reported variations we detected six novel variations: two in the bidirectional promoter region, and one synonymous and three non-synonymous variations in the HSPD1 coding region. One of the non-synonymous variations was polymorphic in patient and control samples, and the rare variations were each only found in single patients and absent in 100 control chromosomes. Functional investigation of the effects of the variations in the promoter region and the non-synonymous variations in the coding region indicated that none of them had a significant impact. Taken together, our data argue against the notion that the chaperonin genes play a major role in the investigated diseases. However, the described variations may represent genetic modifiers with subtle effects.

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Section: Analysis Of Missense Variationsmentioning

confidence: 99%

Single-nucleotide variations in the genes encoding the mitochondrial Hsp60/Hsp10 chaperone system and their disease-causing potential

Bross

Hansen

et al. 2006

J Hum Genet

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“…The mitochondrial Hsp60 (mHsp60) 3 is similar to GroEL in that it is made up of heptameric rings (12-14) that can refold denatured substrates in vitro with the assistance of a co-chaperonin and ATP (15). However, the mHsp60 oligomer is less stable than the bacterial homolog, and it exhibits unique nucleotide binding properties and specificity for co-chaperonin (13,14,16).In addition to their essential function in mediating protein folding, the mammalian mitochondrial chaperonins were also suggested to be involved in extramitochondrial activities. A number of reports have suggested that mHsp60 can stimulate human leukocytes and vascular endothelial cells to produce proinflammatory cytokines (17).…”

mentioning

confidence: 99%

“…The mitochondrial Hsp60 (mHsp60) 3 is similar to GroEL in that it is made up of heptameric rings (12)(13)(14) that can refold denatured substrates in vitro with the assistance of a co-chaperonin and ATP (15). However, the mHsp60 oligomer is less stable than the bacterial homolog, and it exhibits unique nucleotide binding properties and specificity for co-chaperonin (13,14,16).…”

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confidence: 99%

The MitCHAP-60 Disease Is Due to Entropic Destabilization of the Human Mitochondrial Hsp60 Oligomer

Parnas

Nadler

Nisemblat

et al. 2009

Journal of Biological Chemistry

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The 60-kDa heat shock protein (mHsp60) is a vital cellular complex that mediates the folding of many of the mitochondrial proteins. Its function is executed in cooperation with the cochaperonin, mHsp10, and requires ATP. Recently, the discovery of a new mHsp60-associated neurodegenerative disorder, Mit-CHAP-60 disease, has been reported. The disease is caused by a point mutation at position 3 (D3G) of the mature mitochondrial Hsp60 protein, which renders it unable to complement the deletion of the homologous bacterial protein in Escherichia coli (Magen, D., Georgopoulos, C., Bross, P., Ang, D., Segev, Y., Goldsher, D., Nemirovski, A., Shahar, E., Ravid, S., Luder, A., Heno, B., Gershoni-Baruch, R., Skorecki, K., and Mandel, H. (2008) Am. J. Hum. Genet. 83, 30 -42). The molecular basis of the MitCHAP-60 disease is still unknown. In this study, we present an in vitro structural and functional analysis of the purified wild-type human mHsp60 and the MitCHAP-60 mutant. We show that the D3G mutation leads to destabilization of the mHsp60 oligomer and causes its disassembly at low protein concentrations. We also show that the mutant protein has impaired protein folding and ATPase activities. An additional mutant that lacks the first three amino acids (N-del), including Asp-3, is similarly impaired in refolding activity. Surprisingly, however, this mutant exhibits profound stabilization of its oligomeric structure. These results suggest that the D3G mutation leads to entropic destabilization of the mHsp60 oligomer, which severely impairs its chaperone function, thereby causing the disease.Type I chaperonins are essential molecular chaperones of the Hsp60 family found in eubacteria, mitochondria, and chloroplasts (1). They are key players in mediating the correct folding of newly translated, translocated, and stress-denatured proteins. The folding function of chaperonins is executed by the coordinated action of two oligomeric proteins, Hsp60 (also named cpn60 and in bacteria GroEL) and its co-chaperonin Hsp10 (also named cpn10 and in bacteria GroES). The GroEL molecule is composed of 14 subunits that form a barrel-like structure that consists of two back-to-back stacked heptameric rings with a large cavity at each end termed the "Anfinsen cage." GroES is a heptameric ring formed by ϳ10-kDa subunits. The co-chaperonin binds to the chaperonin in the presence of ATP and Mg 2ϩ via a short, unstructured, but highly conserved region known as the mobile loop (2, 3). Due to the stability of the GroEL/ES oligomers and the ease with which they can be purified from bacteria, they have become the primary targets for study in the field of chaperonins. As a result, almost all of our knowledge concerning the structure and mechanism of chaperonins, both Hsp60 and Hsp10, is based largely on data from experiments on these E. coli proteins. The chaperonin reaction cycle starts when a non-folded protein substrate binds to the surface of the cavity of one of the GroEL rings. ATP-dependent GroES binding to that (cis) ring causes a dramatic co...

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“…Therefore, the folding of at least 16 residues is coupled to the binding of 3 residues to GroEL. A multitude of mutations in the mobile loops of GroES and other co-chaperonins is known to affect function (11,(13)(14)(15)(16)(17)(18)(19)(20). Since many of these mutations occur away from residues directly involved in forming the binding interface, we have hypothesized that the mutations affect the folding transition (16).…”

mentioning

confidence: 99%

“…Since many of these mutations occur away from residues directly involved in forming the binding interface, we have hypothesized that the mutations affect the folding transition (16). For example, amino acid substitutions within the mobile loop of GroES but outside of the GroELbinding tripeptide were shown to increase the affinity of GroES for both GroEL and Hsp60, the human mitochondrial homologue (19). The increase in affinity was explained as being a result of decreasing the disorder of the mobile loop or, conversely, preordering the binding structure of the mobile loop.…”

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confidence: 99%

The Disordered Mobile Loop of GroES Folds into a Defined β-Hairpin upon Binding GroEL

Shewmaker¹,

Maskos²,

Simmerling³

et al. 2001

Journal of Biological Chemistry

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The GroES mobile loop is a stretch of ϳ16 amino acids that exhibits a high degree of flexible disorder in the free protein. This loop is responsible for the interaction between GroES and GroEL, and it undergoes a folding transition upon binding to GroEL. Results derived from a combination of transferred nuclear Overhauser effect NMR experiments and molecular dynamics simulations indicate that the mobile loop adopts a ␤-hairpin structure with a Type I, G1 Bulge turn. This structure is distinct from the conformation of the loop in the cocrystal of GroES with GroEL-ADP but identical to the conformation of the bacteriophage-panned "strongly binding peptide" in the co-crystal with GroEL. Analysis of sequence conservation suggests that sequences of the mobile loop and strongly binding peptide were selected for the ability to adopt this hairpin conformation.Chaperonins and co-chaperonins are ring-shaped molecular chaperones. Escherichia coli GroEL and GroES are, respectively, the prototypical chaperonin and co-chaperonin pair. Together, they comprise the GroE intracellular machine that binds, unfolds, and refolds nascent and misfolded proteins (for review, see Refs.

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The Importance of a Mobile Loop in Regulating Chaperonin/ Co-chaperonin Interaction

Cited by 64 publications

References 58 publications

Single-nucleotide variations in the genes encoding the mitochondrial Hsp60/Hsp10 chaperone system and their disease-causing potential

Single-nucleotide variations in the genes encoding the mitochondrial Hsp60/Hsp10 chaperone system and their disease-causing potential

The MitCHAP-60 Disease Is Due to Entropic Destabilization of the Human Mitochondrial Hsp60 Oligomer

The Disordered Mobile Loop of GroES Folds into a Defined β-Hairpin upon Binding GroEL

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