Biosciences Department, Rice University, Houston, TX, USA.
Nat Commun. 2020 Dec 4;11(1):6221. doi: 10.1038/s41467-020-20099-y.
Peroxisomes are vital organelles that compartmentalize critical metabolic reactions, such as the breakdown of fats, in eukaryotic cells. Although peroxisomes typically are considered to consist of a single membrane enclosing a protein lumen, more complex peroxisomal membrane structure has occasionally been observed in yeast, mammals, and plants. However, technical challenges have limited the recognition and understanding of this complexity. Here we exploit the unusually large size of Arabidopsis peroxisomes to demonstrate that peroxisomes have extensive internal membranes. These internal vesicles accumulate over time, use ESCRT (endosomal sorting complexes required for transport) machinery for formation, and appear to derive from the outer peroxisomal membrane. Moreover, these vesicles can harbor distinct proteins and do not form normally when fatty acid β-oxidation, a core function of peroxisomes, is impaired. Our findings suggest a mechanism for lipid mobilization that circumvents challenges in processing insoluble metabolites. This revision of the classical view of peroxisomes as single-membrane organelles has implications for all aspects of peroxisome biogenesis and function and may help address fundamental questions in peroxisome evolution.
过氧化物酶体是真核细胞中分隔关键代谢反应的重要细胞器，例如脂肪的分解。尽管过氧化物酶体通常被认为由一个包裹蛋白质腔的单一膜组成，但在酵母、哺乳动物和植物中偶尔也会观察到更复杂的过氧化物酶体膜结构。然而，技术挑战限制了对这种复杂性的识别和理解。在这里，我们利用拟南芥过氧化物体的异常大尺寸来证明过氧化物体具有广泛的内部膜。这些内部囊泡会随着时间的推移积累，利用 ESCRT（内体分选复合物必需的运输）机制形成，并且似乎来源于外过氧化物酶体膜。此外，这些囊泡可以包含不同的蛋白质，并且当过氧化物体的核心功能——脂肪酸β-氧化受损时，它们不能正常形成。我们的发现为绕过处理不溶性代谢物的挑战的脂动员提供了一种机制。对过氧化物体作为单一膜细胞器的经典观点的修正，对过氧化物体生物发生和功能的各个方面都有影响，并可能有助于解决过氧化物体进化中的基本问题。
