Aguirre Jacob D, Dunkerley Karen M, Mercier Pascal, Shaw Gary S
Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A 3K7, Canada.
Department of Biochemistry, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON N6A 3K7, Canada
Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):298-303. doi: 10.1073/pnas.1613040114. Epub 2016 Dec 22.
Mutations in PARK2 and PARK6 genes are responsible for the majority of hereditary Parkinson's disease cases. These genes encode the E3 ubiquitin ligase parkin and the protein kinase PTEN-induced kinase 1 (PINK1), respectively. Together, parkin and PINK1 regulate the mitophagy pathway, which recycles damaged mitochondria following oxidative stress. Native parkin is inactive and exists in an autoinhibited state mediated by its ubiquitin-like (UBL) domain. PINK1 phosphorylation of serine 65 in parkin's UBL and serine 65 of ubiquitin fully activate ubiquitin ligase activity; however, a structural rationale for these observations is not clear. Here, we report the structure of the phosphorylated UBL domain from parkin. We find that destabilization of the UBL results from rearrangements to hydrophobic core packing that modify its structure. Altered surface electrostatics from the phosphoserine group disrupt its intramolecular association, resulting in poorer autoinhibition in phosphorylated parkin. Further, we show that phosphorylation of both the UBL domain and ubiquitin are required to activate parkin by releasing the UBL domain, forming an extended structure needed to facilitate E2-ubiquitin binding. Together, the results underscore the importance of parkin activation by the PINK1 phosphorylation signal and provide a structural picture of the unraveling of parkin's ubiquitin ligase potential.
PARK2和PARK6基因的突变是大多数遗传性帕金森病病例的病因。这些基因分别编码E3泛素连接酶帕金和蛋白激酶PTEN诱导激酶1(PINK1)。帕金和PINK1共同调节线粒体自噬途径,该途径在氧化应激后回收受损的线粒体。天然帕金是无活性的,以其泛素样(UBL)结构域介导的自抑制状态存在。帕金的UBL结构域中丝氨酸65和泛素的丝氨酸65的PINK1磷酸化可完全激活泛素连接酶活性;然而,这些观察结果的结构原理尚不清楚。在这里,我们报告了帕金磷酸化UBL结构域的结构。我们发现,UBL的不稳定是由疏水核心堆积的重排导致其结构改变引起的。磷酸丝氨酸基团改变的表面静电破坏了其分子内缔合,导致磷酸化帕金的自抑制作用较差。此外,我们表明,UBL结构域和泛素的磷酸化都是激活帕金所必需的,通过释放UBL结构域,形成促进E2-泛素结合所需的延伸结构。总之,这些结果强调了PINK1磷酸化信号激活帕金的重要性,并提供了帕金泛素连接酶潜力解开过程的结构图景。