Magnetization using cheap and minimally toxic materials, such as iron oxide nanoparticles can enable easy separation of cells from culture medium and is relevant to several industrial applications. Here, we show that cell surface expression of a mutant protein that binds iron oxide can enable efficient magnetization of yeast cells. We screened a combinatorial library of mutants derived from the Sso7d protein scaffold to isolate proteins that exhibit preferential binding to iron oxide. One of the isolated mutants, SsoFe2, was chosen for further characterization. Yeast cells expressing SsoFe2 as fusions to a cell wall protein—but not other Sso7d mutants with similar overall protein charge or amino acid composition—preferentially bind iron oxide when present in a solution with high protein concentration and in the presence of 1000-fold excess of competitor yeast cells. Moreover, coexpression of cell surface SsoFe2 enables efficient magnetic capture and separation of yeast cells expressing an enzyme (glucose oxidase) on the cell surface from yeast culture medium, and solutions with high protein concentration or containing other metal oxides. Therefore, SsoFe2-enabled magnetization can enable a range of industrial and biotechnology applications, where easy separation of cells or organelles from complex media is desirable.

中文翻译：

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工程化的Sso7d变体可实现酵母细胞的高效磁化

使用廉价且毒性最小的材料（例如氧化铁纳米颗粒）进行磁化可以使细胞轻松地从培养基中分离出来，并且与几种工业应用有关。在这里，我们表明结合氧化铁的突变蛋白的细胞表面表达可以使酵母细胞有效磁化。我们筛选了衍生自Sso7d蛋白质支架的突变体的组合文库，以分离出表现出与氧化铁优先结合的蛋白质。选择一种分离的突变体SsoFe2进行进一步表征。酵母细胞表达SsoFe2作为与细胞壁蛋白的融合体，但不具有其他具有相似总蛋白电荷或氨基酸组成的Sso7d突变体，当以高蛋白浓度存在1000倍过量的氧化铁时，优先结合氧化铁。竞争酵母细胞。而且，细胞表面SsoFe 2的共表达能够有效地磁性捕获和分离酵母细胞中表达酶（葡萄糖氧化酶）的酵母细胞与酵母培养基以及蛋白质浓度高或含有其他金属氧化物的溶液。因此，启用SsoFe2的磁化可以实现一系列工业和生物技术应用，其中需要将细胞或细胞器与复杂介质轻松分离。细胞表面的共表达SsoFe2能够有效地磁性捕获和分离酵母细胞中表达酶（葡萄糖氧化酶）的酵母细胞，以及酵母中含有高蛋白浓度或其他金属氧化物的溶液。因此，启用SsoFe2的磁化可以实现一系列工业和生物技术应用，其中需要从复杂介质中轻松分离细胞或细胞器。细胞表面的共表达SsoFe2能够有效地磁性捕获和分离酵母细胞中表达酶（葡萄糖氧化酶）的酵母细胞，以及酵母中含有高蛋白浓度或其他金属氧化物的溶液。因此，启用SsoFe2的磁化可以实现一系列工业和生物技术应用，其中需要将细胞或细胞器与复杂介质轻松分离。