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タイトル: | Crystal structure of a thermophilic GrpE protein: insight into thermosensing function for the DnaK chaperone system. |
著者: | Nakamura, Akira Takumi, Kouhei Miki, Kunio |
著者名の別形: | 三木, 邦夫 |
キーワード: | unfolding heat-shock response thermosensor thermal stability protein dynamics |
発行日: | 5-Mar-2010 |
出版者: | Elsevier Ltd |
誌名: | Journal of molecular biology |
巻: | 396 |
号: | 4 |
開始ページ: | 1000 |
終了ページ: | 1011 |
抄録: | A homodimeric GrpE protein functions as a nucleotide exchange factor of the eubacterium DnaK molecular chaperone system. The co-chaperone GrpE accelerates ADP dissociation from, and promotes ATP binding to, DnaK, which cooperatively facilitates the DnaK chaperone cycle with another co-chaperone, DnaJ. GrpE characteristically undergoes two-step conformational changes in response to elevation of the environmental temperature. In the first transition at heat-shock temperatures, a fully reversible and functionally deficient structural alteration takes place in GrpE, and then the higher temperatures lead to the irreversible dissociation of the GrpE dimer into monomers as the second transition. GrpE is also thought to be a thermosensor of the DnaK system, since it is the only member of the DnaK system that changes its structure reversibly and loses its function at heat-shock temperatures of various organisms. We here report the crystal structure of GrpE from Thermus thermophilus HB8 (GrpE(Tth)) at 3.23 A resolution. The resolved structure is compared with that of GrpE from mesophilic Escherichia coli (GrpE(Eco)), revealing structural similarities, particularly in the DnaK interaction regions, and structural characteristics for the thermal stability of GrpE(Tth). In addition, the structure analysis raised the possibility that the polypeptide chain in the reported GrpE(Eco) structure was misinterpreted. Comparison of these two GrpE structures combined with the results of limited proteolysis experiments provides insight into the protein dynamics of GrpE(Tth) correlated with the shift of temperature, and also suggests that the localized and partial unfolding at the plausible DnaK interaction sites of GrpE(Tth) causes functional deficiency of nucleotide exchange factor in response to the heat shock. |
著作権等: | © 2009 Elsevier Ltd この論文は出版社版でありません。引用の際には出版社版をご確認ご利用ください。 This is not the published version. Please cite only the published version. |
URI: | http://hdl.handle.net/2433/132547 |
DOI(出版社版): | 10.1016/j.jmb.2009.12.028 |
PubMed ID: | 20036249 |
出現コレクション: | 学術雑誌掲載論文等 |
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