Hobbs Billy, Limmer Noor, Ossa Felipe, Knüpling Ella, Lenton Samuel, Foderà Vito, Kalverda Arnout P, Karamanos Theodoros K
Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, UK.
The Francis Crick Institute, London, UK.
Nat Commun. 2025 May 31;16(1):5070. doi: 10.1038/s41467-025-60063-2.
J-domain proteins ( JDPs) act as major regulators of the proteostasis network by driving the specificity of the Hsp70 machine. Their important functions are mediated by a low-complexity glycine-/phenylalanine-rich region (GF-linker) that links the folded J-domain with the substrate binding domain. Recently, we and others have shown that in an autoinhibited JDP state, an α-helix formed within the GF-linker blocks the Hsp70 binding site on the J-domain. However, the role of the disordered GF-linker in autoinhibition and how the latter is released, are still not understood. Here, using autoinhibited DNAJB1 and DNAJB6 constructs, we show that in combination with the J-domain, the GF-linker creates a hydrophobic, partially collapsed cluster that shows a remarkable degree of long-range structural communication, disruption of which can lead to destabilisation of autoinhibition. Apart from this crucial intramolecular role, we reveal that the GF-linker can also be recognised by the substrate-binding domain of Hsp70 and dictate the lifetime of the entire JDP-Hsp70 complex. Strikingly, the GF-linkers of DNAJB1 and DNAJB6 display distinct structural properties that lead to different Hsp70 binding kinetics, showing that the behaviour of the GF-linker can vary dramatically even within the same class of JDPs.
J结构域蛋白（JDPs）通过驱动热休克蛋白70（Hsp70）机器的特异性，充当蛋白质稳态网络的主要调节因子。它们的重要功能由一个低复杂性的富含甘氨酸/苯丙氨酸的区域（GF连接区）介导，该区域将折叠的J结构域与底物结合结构域相连。最近，我们和其他人已经表明，在自抑制的JDP状态下，GF连接区内形成的α螺旋会阻断J结构域上的Hsp70结合位点。然而，无序的GF连接区在自抑制中的作用以及后者如何被释放，仍然不清楚。在这里，我们使用自抑制的DNAJB1和DNAJB6构建体表明，与J结构域结合时，GF连接区会形成一个疏水的、部分折叠的簇，该簇显示出显著程度的长程结构通讯，破坏该通讯会导致自抑制的不稳定。除了这个关键的分子内作用外，我们还揭示了GF连接区也可以被Hsp70的底物结合结构域识别，并决定整个JDP-Hsp70复合物的寿命。引人注目的是，DNAJB1和DNAJB6的GF连接区表现出不同的结构特性，导致不同的Hsp70结合动力学，表明即使在同一类JDPs中，GF连接区的行为也可能有很大差异。
