核苷酸结合的第2类伴侣蛋白的多种状态
Multiple states of a nucleotide-bound group 2 chaperonin.
作者信息
Clare Daniel K, Stagg Scott, Quispe Joel, Farr George W, Horwich Arthur L, Saibil Helen R
机构信息
Department of Crystallography, Birkbeck College and Institute of Structural Molecular Biology, University of London, London WC1E 7HX, United Kingdom.
出版信息
Structure. 2008 Apr;16(4):528-34. doi: 10.1016/j.str.2008.01.016.
Chaperonin action is controlled by cycles of nucleotide binding and hydrolysis. Here, we examine the effects of nucleotide binding on an archaeal group 2 chaperonin. In contrast to the ordered apo state of the group 1 chaperonin GroEL, the unliganded form of the homo-16-mer Methanococcus maripaludis group 2 chaperonin is very open and flexible, with intersubunit contacts only in the central double belt of equatorial domains. The intermediate and apical domains are free of contacts and deviate significantly from the overall 8-fold symmetry. Nucleotide binding results in three distinct, ordered 8-fold symmetric conformations--open, partially closed, and fully closed. The partially closed ring encloses a 40% larger volume than does the GroEL-GroES folding chamber, enabling it to encapsulate proteins up to 80 kDa, in contrast to the fully closed form, whose cavities are 20% smaller than those of the GroEL-GroES chamber.
伴侣蛋白的作用受核苷酸结合和水解循环的控制。在这里，我们研究了核苷酸结合对古菌2型伴侣蛋白的影响。与1型伴侣蛋白GroEL的有序无配体状态不同，同型十六聚体的沼泽甲烷球菌2型伴侣蛋白的未结合配体形式非常开放且灵活，亚基间仅在赤道结构域的中央双带处有接触。中间结构域和顶端结构域没有接触，且明显偏离整体的八重对称性。核苷酸结合导致三种不同的、有序的八重对称构象——开放、部分封闭和完全封闭。与完全封闭形式相比，部分封闭的环所包围的体积比GroEL - GroES折叠腔大40%，这使其能够封装高达80 kDa的蛋白质，而完全封闭形式的腔比GroEL - GroES腔小20%。
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