title: Crystal structure and function of an unusual dimeric Hsp20.1 provide insight into the thermal protection mechanism of small heat shock proteins.
abstract: Small heat shock proteins (sHSPs) are ubiquitous chaperones that play a vital role in protein homeostasis. sHSPs are characterized by oligomeric architectures and dynamic exchange of subunits. The flexible oligomeric assembling associating with function remains poorly understood. Based on the structural data, it is certainly agreed that two dimerization models depend on the presence or absence of a β6 strand to differentiate nonmetazoan sHSPs from metazoan sHSPs. Here, we report the Sulfolobus solfataricus Hsp20.1 ACD dimer structure, which shows a distinct dimeric interface. We observed that, in the absence of β6, Hsp20.1 dimer does not depend on β7 strand for forming dimer interface as metazoan sHSPs, nor dissociates to monomers. This is in contrast to other published sHSPs. Our structure reveals a variable, highly polar dimer interface that has advantages for rapid subunits exchange and substrate binding. Remarkably, we find that the C-terminal truncation variant has chaperone activity comparable to that of wild-type despite lack of the oligomer structure. Our further study indicates that the N-terminal region is essential for the oligomer and dimer binding to the target protein. Together, the structure and function of Hsp20.1 give more insight into the thermal protection mechanism of sHSPs.
authors: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
authors: Liang
authors: L
authors: Liu
authors: Institute of Systems Biomedicine and Department of Biophysics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China.
authors: Jiyun
authors: J
authors: Chen
authors: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, China.
authors: Bo
authors: B
authors: Yang
authors: College of Light Industry and Food Sciences, South China University of Technology, Guangzhou 510641, China. Electronic address: yonghw@scut.edu.cn.
authors: Yonghua
authors: Y
authors: Wang
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D050886:HSP20 Heat-Shock Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D018869:Heat-Shock Response; D008969:Molecular Sequence Data; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D048229:Sulfolobus solfataricus / Q000737:chemistry*
chemical_list: D050886:HSP20 Heat-Shock Proteins
keywords: Chaperone activity; Crystal structure; Dimerization; Small heat shock protein (sHSP)