A review on oligomeric polydispersity and oligomers-dependent holding chaperone activity of the small heat-shock protein IbpB of Escherichia coli

Azaharuddin, Md; Pal, Anabadya; Mitra, Sangeeta; Dasgupta, Rakhi; Basu, Tarakdas

doi:10.1007/s12192-023-01392-3

Cited by 3 publications

(2 citation statements)

References 81 publications

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“…A speculation is that they act as an inactive and inert reservoir, providing a constant level of active JB6b in solution. The equilibrium distribution and exchange rates between the assembly states might be changed upon changes in cellular environment, as is for example reported for IbpP and DNAJA2 . Indeed, another amyloid-suppressing chaperone, αB-Crystallin, has a high activation barrier and thus a strong temperature dependence of subunit dissociation …”

Section: Resultsmentioning

confidence: 93%

“…A mainly monomeric mutant of JB6b, called S/TΔ, has a highly reduced fibril suppression capacity, whereas cross-linked JB6b oligomers show no activity . There are examples of other chaperones which have been reported to dissociate into subunits to get full chaperone activity, − and both BRICHOS and HSP60 are examples of amyloid suppressors that are more active when dissociated from larger oligomeric states. , …”

Section: Introductionmentioning

confidence: 99%

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The Ability of DNAJB6b to Suppress Amyloid Formation Depends on the Chaperone Aggregation State

Carlsson,

Axell,

Emanuelsson

et al. 2024

ACS Chem. Neurosci.

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For many chaperones, a propensity to self-assemble correlates with function. The highly efficient amyloid suppressing chaperone DNAJB6b has been reported to oligomerize. A key question is whether the DNAJB6b self-assemblies or their subunits are active units in the suppression of amyloid formation. Here, we address this question using a nonmodified chaperone. We use the well-established aggregation kinetics of the amyloid β 42 peptide (Aβ42) as a readout of the amyloid suppression efficiency. The experimental setup relies on the slow dissociation of DNAJB6b assemblies upon dilution. We find that the dissociation of the chaperone assemblies correlates with its ability to suppress fibril formation. Thus, the data show that the subunits of DNAJB6b assemblies rather than the large oligomers are the active forms in amyloid suppression. Our results provide insights into how DNAJB6b operates as a chaperone and illustrate the importance of established assembly equilibria and dissociation rates for the design of kinetic experiments.

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Section: Resultsmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

The Ability of DNAJB6b to Suppress Amyloid Formation Depends on the Chaperone Aggregation State

Carlsson,

Axell,

Emanuelsson

et al. 2024

ACS Chem. Neurosci.

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Two new oligomers of E. coli small heat‐shock protein IbpB identified under heat stress exhibit maximum holding chaperone activity

Azaharuddin,

Dasgupta,

Das

et al. 2024

FEBS Letters

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Escherichia coli small heat‐shock protein IbpB (MW: 16 KDa) has holding chaperone activity and is present in cells at 30 °C as two large oligomers of MW 2.0–3.0 MDa and 600–700 KDa. We report here about the presence of two additional oligomers of MW around 400 and 130 KDa in cells under heat‐stress at 50 °C. These two smaller oligomers possess the most chaperone activity, as observed from the extent of inhibition of inactivation and aggregation separately, of L‐Lactate dehydrogenase in the presence of the individual oligomers at 52 and 60 °C, respectively. It is suggested here that the two larger oligomers act as poorly active storage forms, which under heat stress dissociate partially into smaller oligomers with high holdase activity.

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Unraveling the Existence of Different Oligomeric Forms of E. Coli Small Heat-Shock Protein Ibpb Under Heat Stress and the Most Functional Oligomers with Respect to Holding Chaperone Activity

Azaharuddin,

Dasgupta,

Das

et al. 2024

Preprint

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A review on oligomeric polydispersity and oligomers-dependent holding chaperone activity of the small heat-shock protein IbpB of Escherichia coli

Cited by 3 publications

References 81 publications

The Ability of DNAJB6b to Suppress Amyloid Formation Depends on the Chaperone Aggregation State

The Ability of DNAJB6b to Suppress Amyloid Formation Depends on the Chaperone Aggregation State

Two new oligomers of E. coli small heat‐shock protein IbpB identified under heat stress exhibit maximum holding chaperone activity

Unraveling the Existence of Different Oligomeric Forms of E. Coli Small Heat-Shock Protein Ibpb Under Heat Stress and the Most Functional Oligomers with Respect to Holding Chaperone Activity

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