The Chaperone Activity of the Developmental Small Heat Shock Protein Sip1 Is Regulated by pH-Dependent Conformational Changes

Fleckenstein, Tilly; Kastenmüller, Andreas; Stein, Manuel; Peters, Carsten; Daake, Marina; Krause, Maike; Weinfurtner, Daniel; Haslbeck, Martin; Weinkauf, Sevil; Groll, M.; Büchner, Johannes

doi:10.1016/j.molcel.2015.04.019

Cited by 47 publications

(59 citation statements)

References 58 publications

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“…If we consider this, the average size of interactors should be even higher. This observation is consistent with the previously described preference for substrate binding of IbpB from Escherichia coli, Hsp20.2 from D. radiodurans, and Caenorhabditis elegans Sip1 and Hsp16.2 (54,55), suggesting that this is a common and conserved feature of the sHsp family. Interestingly, we did not detect a preferential binding to hydrophobic proteins.…”

Section: Discussionsupporting

confidence: 92%

The Chaperone Activity and Substrate Spectrum of Human Small Heat Shock Proteins

Mymrikov

Daake

Richter

et al. 2017

Journal of Biological Chemistry

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Edited by Norma AllewellSmall heat shock proteins (sHsps) are a ubiquitous family of molecular chaperones that suppress the unspecific aggregation of miscellaneous proteins. Multicellular organisms contain a large number of different sHsps, raising questions as to whether they function redundantly or are specialized in terms of substrates and mechanism. To gain insight into this issue, we undertook a comparative analysis of the eight major human sHsps on the aggregation of both model proteins and cytosolic lysates under standardized conditions. We discovered that sHsps, which form large oligomers (HspB1/Hsp27, HspB3, HspB4/␣A-crystallin, and HspB5/␣B-crystallin) are promiscuous chaperones, whereas the chaperone activity of the other sHsps is more substrate-dependent. However, all human sHsps analyzed except HspB7 suppressed the aggregation of cytosolic proteins of HEK293 cells. We identified ϳ1100 heat-sensitive HEK293 proteins, 12% of which could be isolated in complexes with sHsps. Analysis of their biochemical properties revealed that most of the sHsp substrates have a molecular mass from 50 to 100 kDa and a slightly acidic pI (5.4 -6.8). The potency of the sHsps to suppress aggregation of model substrates is correlated with their ability to form stable substrate complexes; especially HspB1 and HspB5, but also B3, bind tightly to a variety of proteins, whereas fewer substrates were detected in complex with the other sHsps, although these were also efficient in preventing the aggregation of cytosolic proteins.

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Section: Discussionsupporting

confidence: 92%

The Chaperone Activity and Substrate Spectrum of Human Small Heat Shock Proteins

Mymrikov

Daake

Richter

et al. 2017

Journal of Biological Chemistry

Self Cite

131

154

View full text Add to dashboard Cite

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“…This interpretation maintains the topology of that observed in the human HspB6/14–3–3 complex (Fig. 4d) and the C. elegans Sip1 32-mer [31], [38] (Suppl. Fig.…”

Section: Resultssupporting

confidence: 83%

“…The direction of the chains (A and C) in the AQ (Fig. 4D) and CD dimer grooves, respectively, is the same as the N-terminal extension in AP grooves in C. elegans Sip1 32-mer, PDB ID 4YDZ, [38] and the human HspB6/14–3–3 hetero-tetramer complex, PDB ID 5LTW, [31] (Suppl. Fig.…”

Section: Discussionmentioning

confidence: 97%

“…The crystal structure (PDB ID 4YDZ) of a metazoan sHsp, Sip1 from Caenorhabditis elegans , shows how 16 AP dimers assemble into a 32-mer by docking C-terminal L-P-I motifs into β4/β8 pockets [38]. The assembly structure shows how the hydrophobic N-terminal sequence 35-FNNIV-39 (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Fig. 1A) from one chain of each AP dimer fills the shared groove [38]. In the crystal structure of the N-terminally phosphorylated human HspB6 dimer complexed with 14–3–3 dimer, there are three hetero-tetramer complexes within the asymmetric unit (PDB ID 5LTW), encompassing three HspB6 dimers formed from chains CD, GH and KL; the N-terminal region of chain G can be traced from 1–38 with residues 27-RLFDQRFG-34 docking into the shared groove of the AP dimer of chains GH [31] (Suppl Fig.…”

Section: Introductionmentioning

confidence: 99%

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Terminal Regions Confer Plasticity to the Tetrameric Assembly of Human HspB2 and HspB3

Clark

Egberts

Kondrat

et al. 2018

Journal of Molecular Biology

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Heterogeneity in small heat shock proteins (sHsps) spans multiple spatiotemporal regimes—from fast fluctuations of part of the protein, to conformational variability of tertiary structure, plasticity of the interfaces, and polydispersity of the inter-converting, and co-assembling oligomers. This heterogeneity and dynamic nature of sHsps has significantly hindered their structural characterization. Atomic coordinates are particularly lacking for vertebrate sHsps, where most available structures are of extensively truncated homomers. sHsps play important roles in maintaining protein levels in the cell and therefore in organismal health and disease. HspB2 and HspB3 are vertebrate sHsps that are found co-assembled in neuromuscular cells, and variants thereof are associated with disease. Here, we present the structure of human HspB2/B3, which crystallized as a hetero-tetramer in a 3:1 ratio. In the HspB2/B3 tetramer, the four α-crystallin domains (ACDs) assemble into a flattened tetrahedron which is pierced by two non-intersecting approximate dyads. Assembly is mediated by flexible “nuts and bolts” involving IXI/V motifs from terminal regions filling ACD pockets. Parts of the N-terminal region bind in an unfolded conformation into the anti-parallel shared ACD dimer grooves. Tracts of the terminal regions are not resolved, most likely due to their disorder in the crystal lattice. This first structure of a full-length human sHsp heteromer reveals the heterogeneous interactions of the terminal regions and suggests a plasticity that is important for the cytoprotective functions of sHsps.

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Dodecameric structure of a small heat shock protein from Mycobacterium marinum M

et al. 2019

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Small heat shock proteins (sHSPs) are ATP‐independent molecular chaperones present ubiquitously in all kingdoms of life. Their low molecular weight subunits associate to form higher order structures. Under conditions of stress, sHSPs prevent aggregation of substrate proteins by undergoing rapid changes in their conformation or stoichiometry. Polydispersity and dynamic nature of these proteins have made structural investigations through crystallography a daunting task. In pathogens like Mycobacteria, sHSPs are immuno‐dominant antigens, enabling survival of the pathogen within the host and contributing to disease persistence. We characterized sHSPs from Mycobacterium marinum M and determined the crystal structure of one of these. The protein crystallized in three different conditions as dodecamers, with dimers arranged in a tetrahedral fashion to form a closed cage‐like architecture. Interestingly, we found a pentapeptide bound to the dodecamers revealing one of the modes of sHSP‐substrate interaction. Further, we have observed that ATP inhibits the chaperoning activity of the protein.

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The Chaperone Activity of the Developmental Small Heat Shock Protein Sip1 Is Regulated by pH-Dependent Conformational Changes

Cited by 47 publications

References 58 publications

The Chaperone Activity and Substrate Spectrum of Human Small Heat Shock Proteins

The Chaperone Activity and Substrate Spectrum of Human Small Heat Shock Proteins

Terminal Regions Confer Plasticity to the Tetrameric Assembly of Human HspB2 and HspB3

Dodecameric structure of a small heat shock protein from Mycobacterium marinum M

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