Caulobacter crescentus Adapts to Phosphate Starvation by Synthesizing Anionic Glycoglycerolipids and a Novel Glycosphingolipid
Caulobacter crescentus Adapts to Phosphate Starvation by Synthesizing Anionic Glycoglycerolipids and a Novel Glycosphingolipid
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DOI：
10.1128/mbio.00107-19
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发表时间：
2019-04
期刊：
影响因子：
6.4
通讯作者：
Gabriele Stankeviciute;Z. Guan;H. Goldfine;Eric A. Klein
中科院分区：
文献类型：
--
作者：
Gabriele Stankeviciute;Z. Guan;H. Goldfine;Eric A. Klein
细菌以多种方式适应环境变化，包括改变细胞形状。新月柄杆菌通过延长其细胞体和包含内膜和外膜的极柄结构来适应磷酸盐饥饿。虽然我们通常认为细胞膜主要由磷脂组成，但当环境磷酸盐以及磷脂合成受到限制时，就会发生细胞伸长。为了适应这些环境限制，C. crescentus 合成了多种糖脂，包括一种新型鞘糖脂。这一发现意义重大，因为鞘糖脂虽然在真核生物中普遍存在，但在细菌中却极其罕见。在本文中，我们鉴定了 GSL-2 合成所需的三种蛋白质，并证明它们有助于噬菌体抗性。这些发现表明，细菌在应对压力时可能会合成比之前观察到的更多种脂质。摘要 新月柄杆菌通过延长细胞体和极柄结构来适应磷酸盐饥饿。茎是革兰氏阴性包膜的延伸，包含内膜和外膜以及肽聚糖细胞壁。细胞伸长需要膜合成增加 6 至 7 倍，但磷酸盐限制会妨碍额外磷脂的掺入。 C. crescentus 可以代替磷脂合成多种糖脂，包括一种新型鞘糖脂 (GSL-2)。虽然鞘糖脂在真核生物中普遍存在，但 GSL-2 在 C. crescentus 中的存在令人惊讶，因为 GSL 以前仅在鞘氨醇单胞菌物种中发现，在鞘氨醇单胞菌物种中，它们在外膜完整性中发挥着作用。在本文中，我们确定了 GSL-2 合成所需的三种蛋白质：CcbF 催化神经酰胺合成的第一步，而 Sgt1 和 Sgt2 依次糖基化神经酰胺以产生 GSL-2。与鞘氨醇单胞菌不同，GSL 在 C. crescentus 中不是必需的。然而，神经酰胺的存在确实有助于噬菌体对阳离子抗菌肽多粘菌素 B 的抗性和敏感性。对磷酸盐饥饿时专门产生的新型脂质种类的鉴定表明，细菌可能能够合成比以前观察到的更广泛的脂质来响应应激。揭示这些脂质及其功能相关性将为微生物生理学和环境适应提供更深入的了解。重要性 细菌以多种方式适应环境变化，包括改变细胞形状。新月柄杆菌通过延长其细胞体和包含内膜和外膜的极柄结构来适应磷酸盐饥饿。虽然我们通常认为细胞膜主要由磷脂组成，但当环境磷酸盐以及磷脂合成受到限制时，就会发生细胞伸长。为了适应这些环境限制，C. crescentus 合成了多种糖脂，包括一种新型鞘糖脂。这一发现意义重大，因为鞘糖脂虽然在真核生物中普遍存在，但在细菌中却极其罕见。在本文中，我们鉴定了 GSL-2 合成所需的三种蛋白质，并证明它们有助于噬菌体抗性。这些发现表明，细菌在应对压力时可能会合成比之前观察到的更多种脂质。
Bacteria adapt to environmental changes in a variety of ways, including altering their cell shape. Caulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure containing both inner and outer membranes. While we generally think of cellular membranes being composed largely of phospholipids, cellular elongation occurs when environmental phosphate, and therefore phospholipid synthesis, is limited. In order to adapt to these environmental constraints, C. crescentus synthesizes several glycolipid species, including a novel glycosphingolipid. This finding is significant because glycosphingolipids, while ubiquitous in eukaryotes, are extremely rare in bacteria. In this paper, we identify three proteins required for GSL-2 synthesis and demonstrate that they contribute to phage resistance. These findings suggest that bacteria may synthesize a wider variety of lipids in response to stresses than previously observed. ABSTRACT Caulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure. The stalk is an extension of the Gram-negative envelope containing inner and outer membranes as well as a peptidoglycan cell wall. Cellular elongation requires a 6- to 7-fold increase in membrane synthesis, yet phosphate limitation would preclude the incorporation of additional phospholipids. In the place of phospholipids, C. crescentus can synthesize several glycolipid species, including a novel glycosphingolipid (GSL-2). While glycosphingolipids are ubiquitous in eukaryotes, the presence of GSL-2 in C. crescentus is surprising since GSLs had previously been found only in Sphingomonas species, in which they play a role in outer membrane integrity. In this paper, we identify three proteins required for GSL-2 synthesis: CcbF catalyzes the first step in ceramide synthesis, while Sgt1 and Sgt2 sequentially glycosylate ceramides to produce GSL-2. Unlike in Sphingomonas, GSLs are nonessential in C. crescentus; however, the presence of ceramides does contribute to phage resistance and susceptibility to the cationic antimicrobial peptide polymyxin B. The identification of a novel lipid species specifically produced upon phosphate starvation suggests that bacteria may be able to synthesize a wider variety of lipids in response to stresses than previously observed. Uncovering these lipids and their functional relevance will provide greater insight into microbial physiology and environmental adaptation. IMPORTANCE Bacteria adapt to environmental changes in a variety of ways, including altering their cell shape. Caulobacter crescentus adapts to phosphate starvation by elongating its cell body and a polar stalk structure containing both inner and outer membranes. While we generally think of cellular membranes being composed largely of phospholipids, cellular elongation occurs when environmental phosphate, and therefore phospholipid synthesis, is limited. In order to adapt to these environmental constraints, C. crescentus synthesizes several glycolipid species, including a novel glycosphingolipid. This finding is significant because glycosphingolipids, while ubiquitous in eukaryotes, are extremely rare in bacteria. In this paper, we identify three proteins required for GSL-2 synthesis and demonstrate that they contribute to phage resistance. These findings suggest that bacteria may synthesize a wider variety of lipids in response to stresses than previously observed.