Simons C Torrey, Staes An, Rommelaere Heidi, Ampe Christophe, Lewis Sally A, Cowan Nicholas J
Department of Biochemistry, New York University Medical Center, New York, New York 10016, USA.
J Biol Chem. 2004 Feb 6;279(6):4196-203. doi: 10.1074/jbc.M306053200. Epub 2003 Nov 22.
Eukaryotic prefoldin (PFD) is a heterohexameric chaperone with a jellyfish-like structure whose function is to deliver nonnative target proteins, principally actins and tubulins, to the eukaryotic cytosolic chaperonin for facilitated folding. Here we demonstrate that functional PFD can spontaneously assemble from its six constituent individual subunits (PFD1-PFD6), each expressed as a recombinant protein. Using engineered forms of PFD assembled in vitro, we show that the tips of the PFD tentacles are required to form binary complexes with authentic target proteins. We show that PFD uses the distal ends of different but overlapping sets of subunits to form stable binary complexes with different target proteins, namely actin and alpha- and beta-tubulin. We also present data that suggest a model for the order of these six subunits within the hexamer. Our data are consistent with the hypothesis that PFD, like the eukaryotic cytosolic chaperonin, has co-evolved specifically to facilitate the folding of its target proteins.
真核生物预折叠蛋白（PFD）是一种具有水母状结构的异源六聚体伴侣蛋白，其功能是将非天然靶蛋白（主要是肌动蛋白和微管蛋白）递送至真核细胞溶质伴侣蛋白以促进折叠。在此我们证明功能性PFD可由其六个组成亚基（PFD1 - PFD6）自发组装而成，每个亚基均作为重组蛋白表达。利用体外组装的工程化形式的PFD，我们表明PFD触手的尖端对于与真实靶蛋白形成二元复合物是必需的。我们表明PFD利用不同但重叠的亚基组的远端与不同的靶蛋白（即肌动蛋白、α - 和β - 微管蛋白）形成稳定的二元复合物。我们还提供了数据，这些数据提示了六聚体内这六个亚基顺序的模型。我们的数据与以下假设一致，即PFD与真核细胞溶质伴侣蛋白一样，已经共同进化以专门促进其靶蛋白的折叠。
