Structural basis of the radicicol resistance displayed by a fungal hsp90.
Structural basis of the radicicol resistance displayed by a fungal hsp90.
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DOI：
10.1021/cb9000316
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发表时间：
2009-04
影响因子：
4
通讯作者：
C. Prodromou;J. Nuttall;S. Millson;S. Roe;T. Sim;D. Tan;P. Workman;L. Pearl;P. Piper
中科院分区：
文献类型：
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作者：
C. Prodromou;J. Nuttall;S. Millson;S. Roe;T. Sim;D. Tan;P. Workman;L. Pearl;P. Piper
热休克蛋白90（Hsp 90）是一个很有前途的癌症药物靶点，因为当它在肿瘤细胞中失去活性时，多种致癌蛋白同时不稳定。高选择性的Hsp 90抑制剂，包括天然抗生素格尔德霉素（GdA）和根赤霉素（RAD），通过占据其核苷酸结合位点来抑制这种必需的分子伴侣。癌症药物治疗通常会受到耐药性发展的影响，但对这些Hsp 90抑制剂的耐药性不应容易因Hsp 90内促进抑制剂结合的那些氨基酸的突变而产生，因为这些氨基酸是伴侣循环的基本ATP结合/ATP酶步骤所需的，并且是严格保守的。尽管如此，RAD产生真菌的Hsp 90显示出对RAD而不是GdA具有异常低的结合亲和力。在其核苷酸结合位点内，正常保守的亮氨酸被异亮氨酸取代，尽管伴侣ATP酶活性没有受到严重影响。插入到酵母的Hsp 90中，这种保守的亮氨酸到异亮氨酸的取代在体外重建了这种降低的对RAD的亲和力。它还产生了实质上增强的抵抗RAD在体内。共晶体结构显示，异亮氨酸的变化与Hsp 90结合RAD的水合作用的局部增加有关，但与GdA无关。据我们所知，这是第一次证明Hsp 90抑制剂耐药性可能通过Hsp 90本身结构的细微改变而产生。
Heat shock protein 90 (Hsp90) is a promising cancer drug target, as multiple oncogenic proteins are destabilized simultaneously when it loses its activity in tumor cells. Highly selective Hsp90 inhibitors, including the natural antibiotics geldanamycin (GdA) and radicicol (RAD), inactivate this essential molecular chaperone by occupying its nucleotide binding site. Often cancer drug therapy is compromised by the development of resistance, but a resistance to these Hsp90 inhibitors should not arise readily by mutation of those amino acids within Hsp90 that facilitate inhibitor binding, as these are required for the essential ATP binding/ATPase steps of the chaperone cycle and are tightly conserved. Despite this, the Hsp90 of a RAD-producing fungus is shown to possess an unusually low binding affinity for RAD but not GdA. Within its nucleotide binding site a normally conserved leucine is replaced by isoleucine, though the chaperone ATPase activity is not severely affected. Inserted into the Hsp90 of yeast, this conservative leucine to isoleucine substitution recreated this lowered affinity for RAD in vitro. It also generated a substantially enhanced resistance to RAD in vivo. Co-crystal structures reveal that the change to isoleucine is associated with a localized increase in the hydration of an Hsp90-bound RAD but not GdA. To the best of our knowledge, this is the first demonstration that it is possible for Hsp90 inhibitor resistance to arise by subtle alteration to the structure of Hsp90 itself.