Prokaryotic nanocompartments, also known as encapsulins, are a recently discovered proteinaceous organelle in prokaryotes that compartmentalize cargo enzymes. While initial studies have begun to elucidate the structure and physiological roles of encapsulins, bioinformatic evidence suggests that a great diversity of encapsulin nanocompartments remains unexplored. Here, we describe a novel encapsulin in the freshwater cyanobacterium Synechococcus elongatus PCC 7942. This nanocompartment is upregulated upon sulfate starvation and encapsulates a cysteine desulfurase enzyme via an N-terminal targeting sequence. Using cryo-electron microscopy, we have determined the structure of the nanocompartment complex to 2.2 Å resolution. Lastly, biochemical characterization of the complex demonstrated that the activity of the cysteine desulfurase is enhanced upon encapsulation. Taken together, our discovery, structural analysis, and enzymatic characterization of this prokaryotic nanocompartment provide a foundation for future studies seeking to understand the physiological role of this encapsulin in various bacteria.

中文翻译：

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发现和表征涉及硫代谢的新的原核纳米小室家族

原核纳米隔室，也称为胶囊蛋白，是原核生物中最近发现的蛋白质细胞器，可分隔货物酶。虽然最初的研究已经开始阐明胶囊蛋白的结构和生理作用，但生物信息学证据表明，胶囊蛋白纳米隔室的多样性仍然没有得到探索。在这里，我们描述了一种新型的胶囊蛋白，在淡水蓝藻长棘突球菌中PCC7942。该纳米隔室在硫酸盐饥饿时上调，并通过N端靶向序列封装了半胱氨酸脱硫酶。使用冷冻电子显微镜，我们已经确定了纳米隔室复合物的结构，分辨率为2.2Å。最后，该复合物的生化特性表明半胱氨酸脱硫酶的活性在包封后得以增强。综上所述，我们对这种原核纳米隔室的发现，结构分析和酶促表征为将来的研究奠定了基础，这些研究旨在了解这种胶囊蛋白在各种细菌中的生理作用。