The Glycine Lipids of Bacteroides thetaiotaomicron Are Important for Fitness during Growth In Vivo and In Vitro
The Glycine Lipids of Bacteroides thetaiotaomicron Are Important for Fitness during Growth In Vivo and In Vitro
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DOI：
10.1128/aem.02157-18
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发表时间：
2019-05-01
影响因子：
4.4
通讯作者：
Clarke, David J.
中科院分区：
文献类型：
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作者：
Lynch, Alli;Tammireddy, Seshu R.;Clarke, David J.
酰化氨基酸在某些细菌中充当细胞膜的重要组成部分。生物合成由氨基酸的 N-酰化起始，随后是酰化分子的 O-酰化，从而产生成熟的二酰化氨基酸脂质。在这项研究中，我们使用遗传学和液相色谱-质谱（LC-MS）来表征多形拟杆菌中产生的二酰化甘氨酸脂质（GL）的生物合成和功能。我们和其他人之前在这项研究中报道了一个名为 glsB 的基因的鉴定，该基因编码负责产生称为 N-酰基-3-羟基棕榈酰甘氨酸（或commandamide）的单酰基化甘氨酸的 N-酰基转移酶活性。在迄今为止测序的所有拟杆菌基因组中，glsB 基因紧邻名为 glsA 的基因下游，预计该基因也编码具有酰基转移酶活性的蛋白质。我们使用 LC-MS 证明 glsB 和 glsA 的共表达导致大肠杆菌中产生 GL。我们在 B. thetaiotaomicron 中构建了 glsB 基因的缺失突变体，并证实 glsB 是 B. thetaiotaomicron 中产生 GL 所必需的。此外，我们发现 glsB 对于 B. thetaiotaomicron 适应应激和在哺乳动物肠道定殖的能力很重要。因此，本报告描述了 GL 生物合成的遗传要求，GL 是一种二酰化氨基酸，有助于人类肠道细菌 B. thetaiotaomicron 的健康。 重要性 肠道微生物组在宿主的健康和疾病中都具有重要作用。哺乳动物肠道微生物组通常以拟杆菌目细菌为主，该目包括拟杆菌和普雷沃菌。在这项研究中，我们鉴定了一种酰化氨基酸，称为甘氨酸脂质，由多形拟杆菌（Bacteroides thetaiotaomicron）产生，这是一种最初从人类肠道中分离出来的有益细菌。除了鉴定产生甘氨酸脂质所需的基因之外，我们还表明甘氨酸脂质在 B. thetaiotaomicron 适应许多环境压力（包括暴露于胆汁或空气）的过程中发挥着重要作用。我们还表明，甘氨酸脂质对于多形拟杆菌在小鼠肠道的正常定植非常重要。这项工作确定甘氨酸脂质是 B. thetaiotaomicron 中重要的适应性决定因素，因此增加了我们对有益细菌在哺乳动物肠道定植的分子机制的理解。
Acylated amino acids function as important components of the cellular membrane in some bacteria. Biosynthesis is initiated by the N-acylation of the amino acid, and this is followed by subsequent O-acylation of the acylated molecule, resulting in the production of the mature diacylated amino acid lipid. In this study, we use both genetics and liquid chromatography-mass spectrometry (LC-MS) to characterize the biosynthesis and function of a diacylated glycine lipid (GL) species produced in Bacteroides thetaiotaomicron. We, and others, have previously reported the identification of a gene, named glsB in this study, that encodes an N-acyltransferase activity responsible for the production of a monoacylated glycine called N-acyl-3-hydroxypalmitoyl glycine (or commendamide). In all of the Bacteroidales genomes sequenced so far, the glsB gene is located immediately downstream from a gene, named glsA, that is also predicted to encode a protein with acyltransferase activity. We use LC-MS to show that the coexpression of glsB and glsA results in the production of GL in Escherichia coli. We constructed a deletion mutant of the glsB gene in B. thetaiotaomicron, and we confirm that glsB is required for the production of GL in B. thetaiotaomicron. Moreover, we show that glsB is important for the ability of B. thetaiotaomicron to adapt to stress and colonize the mammalian gut. Therefore, this report describes the genetic requirements for the biosynthesis of GL, a diacylated amino acid species that contributes to fitness in the human gut bacterium B. thetaiotaomicron.IMPORTANCE The gut microbiome has an important role in both health and disease of the host. The mammalian gut microbiome is often dominated by bacteria from the Bacteroidales, an order that includes Bacteroides and Prevotella. In this study, we have identified an acylated amino acid, called glycine lipid, produced by Bacteroides thetaiotaomicron, a beneficial bacterium originally isolated from the human gut. In addition to identifying the genes required for the production of glycine lipids, we show that glycine lipids have an important role during the adaptation of B. thetaiotaomicron to a number of environmental stresses, including exposure to either bile or air. We also show that glycine lipids are important for the normal colonization of the murine gut by B. thetaiotaomicron. This work identifies glycine lipids as an important fitness determinant in B. thetaiotaomicron and therefore increases our understanding of the molecular mechanisms underpinning colonization of the mammalian gut by beneficial bacteria.