Myopathy-causing Mutations in an HSP40 Chaperone Disrupt Processing of Specific Client Conformers
Myopathy-causing Mutations in an HSP40 Chaperone Disrupt Processing of Specific Client Conformers
复制标题
DOI：
10.1074/jbc.m114.572461
复制
发表时间：
2014-07-25
影响因子：
4.8
通讯作者：
True, Heather L.
中科院分区：
文献类型：
--
作者：
Stein, Kevin C.;Bengoechea, Rocio;True, Heather L.
分子伴侣网络可以防止蛋白质的毒性错误折叠和聚集。这个网络的破坏导致各种蛋白质构象紊乱。最近发现的一个这样的例子是肢带型肌营养不良症1D型（LGMD 1D），这是由HSP 40伴侣DNAJB 6突变引起的。所有LGMD 1D相关突变定位于DNAJB 6的保守G/F结构域，但该结构域的功能在很大程度上是未知的。在这里，我们利用酵母HSP 40 Sis 1，它具有已知的聚集倾向的客户端蛋白，深入了解G/F结构域的作用及其在LGMD 1D发病机制中的意义。引人注目的是，我们证明，LGMD 1D突变的Sis 1-DNAJB 6嵌合体差异损害两个酵母朊病毒，[RNQ+]和[PSI+]的特定构象的加工。重要的是，这些差异并不仅仅与这些朊病毒株对伴侣蛋白水平变化的敏感性相关。此外，我们分析了LGMD 1D相关DNAJB 6突变对TDP-43的影响，TDP-43是一种已知在LGMD 1D中形成包涵体的蛋白质。我们表明，DNAJB 6 G/F结构域突变体破坏了哺乳动物细胞核TDP-43应激颗粒的加工。这些数据表明，G/F结构域介导的伴侣-底物相互作用的方式，延伸到一个特定的客户端的识别和客户端构象的子集。我们建议，这种选择性的伴侣破坏可能会导致有毒的聚集体构象的积累，并导致LGMD 1D和其他蛋白质构象障碍的发展。
The molecular chaperone network protects against the toxic misfolding and aggregation of proteins. Disruption of this network leads to a variety of protein conformational disorders. One such example recently discovered is limb-girdle muscular dystrophy type 1D (LGMD1D), which is caused by mutation of the HSP40 chaperone DNAJB6. All LGMD1D-associated mutations localize to the conserved G/F domain of DNAJB6, but the function of this domain is largely unknown. Here, we exploit the yeast HSP40 Sis1, which has known aggregation-prone client proteins, to gain insight into the role of the G/F domain and its significance in LGMD1D pathogenesis. Strikingly, we demonstrate that LGMD1D mutations in a Sis1-DNAJB6 chimera differentially impair the processing of specific conformers of two yeast prions, [RNQ+] and [PSI+]. Importantly, these differences do not simply correlate to the sensitivity of these prion strains to changes in chaperone levels. Additionally, we analyzed the effect of LGMD1D-associated DNAJB6 mutations on TDP-43, a protein known to form inclusions in LGMD1D. We show that the DNAJB6 G/F domain mutants disrupt the processing of nuclear TDP-43 stress granules in mammalian cells. These data suggest that the G/F domain mediates chaperone-substrate interactions in a manner that extends beyond recognition of a particular client and to a subset of client conformers. We propose that such selective chaperone disruption may lead to the accumulation of toxic aggregate conformers and result in the development of LGMD1D and perhaps other protein conformational disorders.