Zhou Wenbo, Zhu Min, Wilson Mark A, Petsko Gregory A, Fink Anthony L
Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA.
J Mol Biol. 2006 Mar 3;356(4):1036-48. doi: 10.1016/j.jmb.2005.12.030. Epub 2005 Dec 27.
DJ-1 has been reported to have chaperone activity by preventing the aggregation of some proteins, and by structural analogy to Hsp31. The L166P mutation has been linked to a familial early onset form of Parkinson's disease (PD). Since the aggregation of alpha-synuclein is believed to be a critical step in the etiology of PD, we have investigated the interaction of wild-type DJ-1 and its oxidized forms with alpha-synuclein. Native (unoxidized) DJ-1 did not inhibit alpha-synuclein fibrillation, and no evidence for stable interactions between alpha-synuclein and native DJ-1 was observed. However, DJ-1 is very susceptible to oxidation by the addition of two oxygen atoms to form the sulfinic acid of Cys106 (2O DJ-1) (no 1O oxidized state is detectable). 2O DJ-1 was readily prepared by the addition of H(2)O(2) at concentrations up to a 20-fold molar excess. The oxidation of Cys106 to the sulfinic acid had minimal effect on the structural properties of DJ-1. However, 2O DJ-1 was very effective in preventing the fibrillation of alpha-synuclein, and only this form of DJ-1 appears to have significant anti-aggregation properties against alpha-synuclein. Further oxidation of DJ-1 leads to loss of some secondary structure, and to loss of the ability to inhibit alpha-synuclein fibrillation. Our observations confirm the suggestion that DJ-1 may act as an oxidative-stress-induced chaperone to prevent alpha-synuclein fibrillation. Since oxidative stress has been associated with PD, this observation may explain why mutations of DJ-1 could be a contributing factor in PD, and also indicates that excess oxidative stress could also lead to enhanced alpha-synuclein aggregation and hence PD.
据报道，DJ-1通过防止某些蛋白质聚集以及在结构上与Hsp31相似而具有伴侣活性。L166P突变与帕金森病（PD）的家族性早发形式有关。由于α-突触核蛋白的聚集被认为是PD病因中的关键步骤，我们研究了野生型DJ-1及其氧化形式与α-突触核蛋白的相互作用。天然（未氧化）DJ-1不抑制α-突触核蛋白的纤维化，并且未观察到α-突触核蛋白与天然DJ-1之间稳定相互作用的证据。然而，DJ-1极易被氧化，通过添加两个氧原子形成Cys106的亚磺酸（2O DJ-1）（未检测到单氧氧化态）。通过添加高达20倍摩尔过量的H2O2可轻松制备2O DJ-1。Cys106氧化为亚磺酸对DJ-1的结构特性影响最小。然而，2O DJ-1在防止α-突触核蛋白纤维化方面非常有效，并且只有这种形式的DJ-1似乎对α-突触核蛋白具有显著的抗聚集特性。DJ-1的进一步氧化导致一些二级结构丧失，并导致抑制α-突触核蛋白纤维化的能力丧失。我们的观察结果证实了DJ-1可能作为氧化应激诱导的伴侣蛋白来防止α-突触核蛋白纤维化的建议。由于氧化应激与PD有关，这一观察结果可以解释为什么DJ-1突变可能是PD的一个促成因素，也表明过量的氧化应激也可能导致α-突触核蛋白聚集增强，从而导致PD。
