Intrinsically Disordered Regions in Autophagy Proteins

描述（由申请人提供）：自噬负责不需要的、受损的或有害的大分子细胞质组分的囊泡隔离和溶酶体降解，导致营养物质再循环。因此，自噬在广泛的生物体内平衡过程中起着重要作用，包括寿命延长，胚胎发育，组织分化，细胞生长，生存环境应激条件如饥饿，高温和缺氧以及内部应激源如受损的细胞器，突变蛋白，自由基和细胞内病原体。自噬缺陷与许多疾病有关，如寿命缩短，神经退行性疾病和肌肉疾病，对感染性疾病的免疫力减弱;因此，阐明自噬蛋白的结构机制对于理解这些疾病并设计针对它们的潜在治疗方法至关重要。蛋白质内无序区（IDR），即缺乏有序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的选定子集中的结构紊乱，包括保守的自噬效应子Beclin 1内的大IDR，Beclin 1是自噬成核复合物的重要组成部分。此外，基于生物信息学分析的结果，以调查潜在的生物功能的IDRs介导的蛋白质相互作用，我们实验研究选定的结合基序内预测选定的IDRs，以及在这些IDRs的构象转变，特别关注的Beclin 1 IDR。此外，我们已经确定了Beclin 1 IDR的几种预期的蛋白质相互作用，这些将通过实验验证。Beclin 1与许多人类疾病直接相关。Beclin 1水平降低与寿命缩短和老年性疾病（如阿尔茨海默病）风险升高有关;而Beclin 1介导的自噬增加，如通过热量限制，增加细胞和生物体寿命。Beclin 1似乎是自噬的蛋白质相互作用中心，因为它与至少20种其他细胞蛋白质相互作用。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理解，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，这些相互作用在人类疾病中的破坏作用以及靶向Beclin 1 IDR或其相互作用的潜在治疗方法。

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.