High activity of Mj HSP16.5 under acidic condition
Wang Zheng1,2; Cao AoNeng1,2,3; Lai LuHua1,2
AbstractSmall heat shock proteins (sHSPs) exist ubiquitously among all organisms, with a variety of functions. All small heat shock proteins assemble into a native large oligomeric state containing 9-40 monomers. The sHSPs show chaperone-like activity to prevent the aggregation of nonnative proteins under stressful cellular conditions such as non-optimal temperatures, pH changes, osmotic pressure, and exposure to toxic chemicals. It was found that a common dimeric subunit of sHSPs might be the major active species, but whether the native large oligomeric state is only a storage state or a state crucial to its molecular chaperone activity is still under debate. The native large oligomeric state of the small heat shock protein from a hyperthermophilic methanarchaeon, Methanococcus jannaschii (Mj HSP 16.5), is a stable icositetramer, which is a symmetric hollow sphere that is very stable even at 85A degrees C, and no small active subunit has been detected till now. Our results show that Mj sHSP 16.5 changes into small and active oligomeric state at pH 3, likely as octamers (average result) at 25A degrees C, and dimers at 65A degrees C. The dimer of Mj HSP 16.5 at pH 3.0 and 65A degrees C is very active and efficient, even 7-fold more efficient than the high-temperature-activated icositetramer at neutral pH. Monomer exchange can be observed between dimers of Mj HSP 16.5 at pH 3.0 and 65A degrees C. These results not only demonstrate that the icositetramer structure of Mj sHSP16.5 is not necessary for its molecular chaperone activity, but also suggest that Mj sHSP16.5 is a very efficient chaperone acting at high temperature and under the acidic condition. Even though it is not clear whether the native environment of Methanococcus jannaschii is acidic or not, given its ability to excrete acidic compounds, it is likely that Methanococcus jannaschii will encounter acidic internal or external environments at high temperature. Our results demonstrate that Mj HSP 16.5 may help Methanococcus jannaschii to survive better under those extreme environmental conditions.
KeywordSmall Heat Shock Protein Chaperone Mj Hsp16.5 Dimer Acidic Folding Aggregation
Indexed BySCI
WOS IDWOS:000264886800012
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Cited Times:2[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Corresponding AuthorCao AoNeng
Affiliation1.Peking Univ, Beijing Natl Lab Mol Sci, Coll Chem & Mol Engn, Beijing 100871, Peoples R China
2.Peking Univ, State Key Lab Struct Chem Stable & Unstable Speci, Coll Chem & Mol Engn, Beijing 100871, Peoples R China
3.Shanghai Univ, Inst Nanochem & Nanobiol, Shanghai 200444, Peoples R China
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Wang Zheng,Cao AoNeng,Lai LuHua. High activity of Mj HSP16.5 under acidic condition[J]. SCIENCE IN CHINA SERIES B-CHEMISTRY,2009,52(3):325-331.
APA Wang Zheng,Cao AoNeng,&Lai LuHua.(2009).High activity of Mj HSP16.5 under acidic condition.SCIENCE IN CHINA SERIES B-CHEMISTRY,52(3),325-331.
MLA Wang Zheng,et al."High activity of Mj HSP16.5 under acidic condition".SCIENCE IN CHINA SERIES B-CHEMISTRY 52.3(2009):325-331.
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