Small heat shock protein Hsp16.3 modulates its chaperone activity by adjusting the rate of oligomeric dissociation

Fu, Xinmiao; Liu, Chong; Liu, Yang; Feng, Xiuguang; Gu, Liangcai; Chen, Xiaoyou; Chang, Zengyi

doi:10.1016/j.bbrc.2003.09.027

Cited by 41 publications

(32 citation statements)

References 40 publications

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“…Second, a dimeric mutant protein (⌬C9) of Hsp16.3, with 9 residues from the C-terminal removed, was found to be able to exhibit efficient chaperonelike activity even at room temperature, suggesting that the dissociated small oligomers are the active forms. This finding is in complete accordance with the hypothesis that the nonameric dissociation is a prerequisite for Hsp16.3 to exhibit chaperonelike activity and that the dissociated oligomeric form is active (13)(14)(15). Taken together, our accumulative observations, in agreement with reports on Hsp16.5, ␣A-and ␣B-crystallins (19,43,44), but unlike those on the C. elegans sHSPs (20, 21, 37), Synechocystis sp.…”

Section: Discussionsupporting

confidence: 92%

“…The dual role attributed to the N-terminal region of Hsp6.3 in both substrate-binding and the formation of nonamers from trimers would provide an effective mechanism for the small heat shock protein to modulate its chaperone-like activity through oligomeric dissociation/reassociation in responding to environmental conditions as repeatedly implied in our previous investigations (13)(14)(15). In addition, it is conceivable that the C-terminal extension, the removal of which leads to the generation of smaller oligomeric forms that exhibit efficient chaperone-like activities even at room temperature, might also play a certain role in modulating the oligomeric state and in turn the chaperone-like activity of the Hsp16.3 protein.…”

Section: Discussionmentioning

confidence: 60%

“…Previous studies have demonstrated that Hsp16.3: 1) exists as nonamers, which are assembled by using trimers and hexamers as intermediates (27,31); 2) undergo dynamic oligomeric dissociation/reassociation (13,14); and 3) exhibit chaperone-like activities that are modulated by adjusting the equilibrium and/or rate of the oligomeric dissociation process (13)(14)(15). The data presented here conclusively demonstrate that the N-terminal region of Hsp16.3 is not only involved in the formation of nonamers from trimers but also contains the critical site for binding denaturing substrate proteins.…”

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confidence: 99%

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A Dual Role for the N-terminal Region of Mycobacterium tuberculosis Hsp16.3 in Self-oligomerization and Binding Denaturing Substrate Proteins

Zhang

et al. 2005

Journal of Biological Chemistry

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The N-terminal regions, which are highly variable in small heat-shock proteins, were found to be structurally disordered in all the 24 subunits of Methanococcus jannaschii Hsp16.5 oligomer and half of the 12 subunits of wheat Hsp16.9 oligomer. The structural and functional roles of the corresponding region (potentially disordered) in Mycobacterium tuberculosis Hsp16.3, existing as nonamers, were investigated in this work. The data demonstrate that the mutant Hsp16.3 protein with 35 N-terminal residues removed (⌬N35) existed as trimers/ dimers rather than as nonamers, failing to bind the hydrophobic probe (1,1-bi(4-anilino)naphthalene-5,5-disulfonic acid) and exhibiting no chaperone-like activity. Nevertheless, another mutant protein with the C-terminal extension (of nine residues) removed, although existing predominantly as dimers, exhibited efficient chaperone-like activity even at room temperatures, indicating that pre-existence as nonamers is not a prerequisite for its chaperone-like activity. Meanwhile, the mutant protein with both the N-and C-terminal ends removed fully exists as a dimer lacking any chaperonelike activity. Furthermore, the N-terminal region alone, either as a synthesized peptide or in fusion protein with glutathione S-transferase, was capable of interacting with denaturing proteins. These observations strongly suggest that the N-terminal region of Hsp16.3 is not only involved in self-oligomerization but also contains the critical site for substrate binding. Such a dual role for the N-terminal region would provide an effective mechanism for the small heat-shock protein to modulate its chaperone-like activity through oligomeric dissociation/reassociation. In addition, this study demonstrated that the wild-type protein was able to form heterononamers with ⌬N35 via subunit exchange at a subunit ratio of 2:1. This implies that the 35 N-terminal residues in three of the nine subunits in the wild-type nonamer are not needed for the assembly of nonamers from trimers and are thus probably structurally disordered.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 60%

mentioning

confidence: 99%

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A Dual Role for the N-terminal Region of Mycobacterium tuberculosis Hsp16.3 in Self-oligomerization and Binding Denaturing Substrate Proteins

Zhang

et al. 2005

Journal of Biological Chemistry

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“…20,32 Although little is known about the mechanism or kinetics of this process, increasing evidence suggests that subunit exchange is essential for chaperone activity. [33][34][35] To determine if this relationship is also exhibited by Hsp27, the subunit exchange kinetics of wild-type Hsp27 were compared to those of the deletion variants. The protocol for fluorescence resonance energy transfer (FRET) experiments reported previously to study the subunit exchange kinetics of Hsp27 32,36 was used in this study.…”

Section: Subunit Exchangementioning

confidence: 99%

Roles of the N‐ and C‐terminal sequences in Hsp27 self‐association and chaperone activity

Lelj-Garolla

Mauk

2011

Protein Science

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The small heat shock protein 27 (Hsp27 or HSPB1) is an oligomeric molecular chaperone in vitro that is associated with several neuromuscular, neurological, and neoplastic diseases. Although aspects of Hsp27 biology are increasingly well known, understanding of the structural basis for these involvements or of the functional properties of the protein remains limited. As all 11 human small heat shock proteins (sHsps) possess an a-crystallin domain, their varied functional and physiological characteristics must arise from contributions of their nonconserved sequences. To evaluate the role of two such sequences in Hsp27, we have studied three Hsp27 truncation variants to assess the functional contributions of the nonconserved N-and C-terminal sequences. The N-terminal variants D1-14 and D1-24 exhibit little chaperone activity, somewhat slower but temperature-dependent subunit exchange kinetics, and temperature-independent self-association with formation of smaller oligomers than wild-type Hsp27. The C-terminal truncation variants exhibit chaperone activity at 40°C but none at 20°C, limited subunit exchange, and temperatureindependent self-association with an oligomer distribution at 40°C that is very similar to that of wild-type Hsp27. We conclude that more of the N-terminal sequence than simply the WPDF domain is essential in the formation of larger, native-like oligomers after binding of substrate and/or in binding of Hsp27 to unfolding peptides. On the other hand, the intrinsically flexible C-terminal region drives subunit exchange and thermally-induced unfolding, both of which are essential to chaperone activity at low temperature and are linked to the temperature dependence of Hsp27 self-association.

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“…Shifting to small Hsps, Zengyi Chang (Peking University, Beijing, People's Republic of China) and his students Xinmiao Fu and Wangwang Jiao (Tsinghua University, Beijing, People's Republic of China) presented work on the assembly and chaperone-like activity of the Mycobacterium tuberculosis Hsp16.3 nonamers (Fu et al 2003) and of the small IbpB protein of Escherichia coli. In a coupled transcription-translation assay, Hsp16.3 exists primarily as a trimer that can form nonamers through subunit exchange in the presence of purified Hsp16.3.…”

Section: The Chaperone Machine and Its Regulationmentioning

confidence: 99%

Stress under the dam: meeting report of the Fourth International Workshop on the Molecular Biology of Stress Responses

Currie

Tanguay

2004

Cell Stress Chaper

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Small heat shock protein Hsp16.3 modulates its chaperone activity by adjusting the rate of oligomeric dissociation

Cited by 41 publications

References 40 publications

A Dual Role for the N-terminal Region of Mycobacterium tuberculosis Hsp16.3 in Self-oligomerization and Binding Denaturing Substrate Proteins

A Dual Role for the N-terminal Region of Mycobacterium tuberculosis Hsp16.3 in Self-oligomerization and Binding Denaturing Substrate Proteins

Roles of the N‐ and C‐terminal sequences in Hsp27 self‐association and chaperone activity

Stress under the dam: meeting report of the Fourth International Workshop on the Molecular Biology of Stress Responses

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