CCT与ATP结合形式的三维重建揭示了II型伴侣蛋白的不对称折叠构象。

3D reconstruction of the ATP-bound form of CCT reveals the asymmetric folding conformation of a type II chaperonin.

作者信息

Llorca O, Smyth M G, Carrascosa J L, Willison K R, Radermacher M, Steinbacher S, Valpuesta J M

机构信息

Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma de Madrid, Spain.

出版信息

Nat Struct Biol. 1999 Jul;6(7):639-42. doi: 10.1038/10689.

DOI:10.1038/10689

PMID:10404219

Abstract

The type II chaperonin CCT (chaperonin containing Tcp-1) of eukaryotic cytosol is a heteromeric 16-mer particle composed of eight different subunits. Three-dimensional reconstructions of apo-CCT and ATP-CCT have been obtained at 28 A resolution by cryo-electron microscopy. Binding of ATP generates an asymmetric particle; one ring has a slightly different conformation from the apo-CCT ring, while the other has undergone substantial movements in the apical domains. Upon ATP binding the apical domains rotate and point towards the cylinder axis, so that the helical protrusions present at their tips could act as a lid closing the ring cavity.

摘要

真核细胞质中的II型伴侣蛋白CCT（含Tcp-1的伴侣蛋白）是一种由八个不同亚基组成的异源十六聚体颗粒。通过冷冻电子显微镜已在28埃分辨率下获得了脱辅基CCT和ATP-CCT的三维重建图像。ATP的结合产生了一个不对称颗粒；一个环的构象与脱辅基CCT环略有不同，而另一个环在顶端结构域发生了显著移动。ATP结合后，顶端结构域旋转并指向圆柱轴，使得其顶端的螺旋突起可作为封闭环腔的盖子发挥作用。