Members of the Bacteroidota compose a large portion of the human gut microbiota, contributing to overall gut health via the degradation of various polysaccharides. This process is facilitated by lipoproteins, globular proteins anchored to the cell surface by a lipidated N-terminal cysteine. Despite their importance, lipoprotein synthesis by these bacteria is understudied. In Escherichia coli , the α-amino-linked lipid of lipoproteins is added by the l ipoprotein N -acyl t ransferase Lnt. Herein, we have identified a protein distinct from Lnt responsible for the same process in Bacteroides , named l ipoprotein N -acyltransferase in B acteroides (Lnb). Deletion of Lnb yields cells that synthesize diacylated lipoproteins, with impacts on cell viability and morphology, growth on polysaccharides, and protein composition of membranes and outer membrane vesicles (OMVs). Our results not only challenge the accepted paradigms of lipoprotein biosynthesis in gram-negative bacteria but also suggest the existence of a new family of lipoprotein N -acyltransferases.

中文翻译：

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拟杆菌中脂蛋白 N-酰基转移酶的鉴定和表征


拟杆菌属的成员构成了人类肠道微生物群的很大一部分，通过降解各种多糖为整体肠道健康做出贡献。脂蛋白促进了这一过程，脂蛋白是通过脂质化的 N 末端半胱氨酸锚定在细胞表面的球状蛋白。尽管它们很重要，但这些细菌的脂蛋白合成研究不足。在大肠杆菌中，脂蛋白的 α-氨基连接脂质由 l ipoprotein N -酰基 t ransferase Lnt 添加。在此，我们鉴定了一种不同于 Lnt 的蛋白质，在拟杆菌中负责相同的过程，在 B acteroides （Lnb） 中命名为 l ipoprotein N-酰基转移酶。Lnb 缺失产生合成二酰化脂蛋白的细胞，影响细胞活力和形态、多糖生长以及膜和外膜囊泡 （OMV） 的蛋白质组成。我们的结果不仅挑战了革兰氏阴性细菌中脂蛋白生物合成的公认范式，而且还表明存在一个新的脂蛋白 N-酰基转移酶家族。