Intrinsically Disordered Regions in Autophagy Proteins

描述(申请人提供)：自噬负责不需要的、受损的或有害的大分子细胞质成分的囊泡隔离和溶酶体降解，导致营养循环。因此，自噬在生命周期延长、胚胎发育、组织分化、细胞生长、饥饿、高温和低氧等环境应激条件以及细胞器受损、突变蛋白、自由基和细胞内病原体等内部应激源的生存过程中发挥着重要的作用。自噬缺陷与许多疾病有关，如寿命缩短、神经退行性和肌肉疾病、对感染性疾病的年龄免疫力减弱等；因此，阐明自噬蛋白基于结构的机制对于了解这些疾病和设计针对这些疾病的潜在治疗方法至关重要。固有无序区(IDR)，即缺乏有序的二级和三级结构的区域，是许多蛋白质的常见但知之甚少的特征。与阿尔茨海默病等神经退行性疾病等重要疾病有关的突变通常映射到IDR。我们的生物信息学分析表明，IDR是自噬蛋白的主要特征。我们通过实验验证了自噬蛋白IDR的一个选定子集中的结构紊乱，包括保守的自噬效应器Beclin 1中的一个大IDR，Beclin 1是自噬核复合体的重要组成部分。此外，基于生物信息学分析的结果，以研究IDR在介导蛋白质相互作用中的潜在生物学功能为基础，我们通过实验研究了在选定的IDR中预测的一些结合基序，以及这些IDR中的构象转变，特别是Beclin 1 IDR。此外，我们已经确定了Beclin 1 IDR的几个预期的蛋白质相互作用，这些将得到实验验证。Beclin-1与许多人类疾病有直接关系。Beclin 1水平的降低与寿命的缩短和阿尔茨海默病等与年龄相关的疾病的风险增加有关；而Beclin 1介导的自噬增加，例如通过限制卡路里，延长细胞和生物的寿命。Beclin 1似乎是自噬的蛋白质相互作用中心，因为它与至少20个其他细胞蛋白的相互作用有关。这项工作将为未来的研究奠定基础，建立对这些相互作用的详细结构和机制的理解，从而阐明这些相互作用如何相互竞争或相互补充，以调节Beclin 1介导的自噬，这些相互作用的中断在人类疾病中的作用，以及针对Beclin 1 IDR或其相互作用的潜在疗法。

DESCRIPTION (provided by applicant): Autophagy is responsible for the vesicular sequestration and lysosomal degradation of unwanted, damaged or harmful macromolecular cytoplasmic components, resulting in nutrient recycling. Thus, autophagy plays an important role in a wide range of organismal homeostasis processes including life-span extension, embryonic development, tissue-differentiation, cell-growth, surviving environmental stress conditions like starvation, high temperatures and hypoxia as well as internal stressors like damaged organelles, mutant proteins, free radicals and intracellular pathogens. Defects in autophagy are implicated in many disorders such as reduced life-span, neurodegenerative and muscular disorders, age-weakened immunity against infectious diseases; hence, elucidating the structure-based mechanism of autophagy proteins is essential to understanding these diseases and devising potential therapeutics targeting them. Intrinsically disordered regions (IDRs), i.e. regions that lack ordered secondary and tertiary structure, are common, yet poorly understood, features of many proteins. Mutations implicated in important diseases like neurodegenerative disorders like Alzheimer's disease often map to IDRs. Our bioinformatics analysis shows that IDRs are a predominant feature of autophagy proteins. We experimentally verify structural disorder in a selected subset of autophagy protein IDRs, including a large IDR within the conserved autophagy effector, Beclin 1, an essential component of the autophagy nucleation complex. Further, based on the results of a bioinformatics analyses to investigate the potential biological function of IDRs in mediating protein interactions, we experimentally investigate selected binding motifs predicted within selected IDRs, as well as conformational transitions in these IDRs, with a special focus on the Beclin 1 IDR. Further, we have identified several prospective protein interactions of the Beclin 1 IDR, and these will be experimentally validated. Beclin 1 is directly implicated in many human diseases. Reduced Beclin 1 levels are associated with decreased longevity and an elevated risk of age-related disorders like Alzheimer's disease; while an increase in Beclin 1-mediated autophagy, such as by caloric restriction, increases cellular and organismal life span. Beclin 1 appears to be a protein interaction hub for autophagy as it is implicated in interactions with at least 20 other cellular proteins. The work in this propsal will lay the groundwork for future research building a detailed structural and mechanistic understanding of these interactions that will elucidate how these interactions compete with or complement each other to regulate Beclin 1-mediated autophagy, the role of disruptions of these interactions in human diseases and potential therapeutics that target the Beclin 1 IDR or its interactions.