Bacterial sphingolipids - revealing hidden biosynthetic pathways of key players in host-microbe interactions.

细菌鞘脂 - 揭示宿主与微生物相互作用中关键参与者的隐藏生物合成途径。

• 批准号: BB/V001620/1
• 负责人: Dominic Campopiano
• 金额: $ 51.08万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FV001620%2F1
• 关键词: Bacterial; sphingolipids; revealing; hidden; biosynthetic

Animal and bacterial cells have a protective, water-resistant outer shell that is composed of molecules with a water-loving (hydrophilic) head group and a long, water-hating (hydrophobic) tail. This large family of molecules are called lipids and include common things like saturated/unsaturated fats and cholesterol. One particular sub-family of lipids is called sphingolipids (SLs) and their more complex ceramide versions (which have two fatty tails). The SLs not only play structural roles in the outer shell that allow the cell membrane to resist water and let nutrients in and waste out; they are also able to stimulate the human immune system. SL levels are dynamic but also tightly controlled - any increase or decrease in the cellular SL levels is a sign that something has gone wrong. Changes in SL levels are strongly linked with old age and diseases such as Alzheimer's, diabetes, asthma, cancer and nerve-wasting diseases. An exciting area of research with direct implications for human health is the discovery that humans are hosts for many different types of bacteria - collectively these are known as the microbiota/microbiome. Current estimates are that for every human cell in our body, there is a bacterial one. These bacteria can be "bad" and cause disease (e.g. superbugs) but most are "good" bacteria and are beneficial to our well being. These bacteria live in our mouths, on our skin and in our gut and help us metabolise our food and are also thought to play protective roles. A surprising discovery was that the bacteria that live with us produce molecules that allow bacterial and human cells to communicate. One such family of molecules are the SLs - it is highly unusual that human and bacterial cells both make the same molecule and this suggests some sort of evolutionary link. Moreover, it has been calculated that we have several grams of SLs in our gut at any one time and they are making a vital contribution to our health. Recent studies have linked the microbiota to diseases such as diabetes, obesity and cancer.All cells make SLs by a multi-step pathway using simple building blocks - the steps are catalysed (sped up) by molecular machines called enzymes. Research has focussed on the enzymes involved in human SL biosynthesis but very little is known about SL biosynthesis in the microbiota. To fully understand the relationship between us and bacteria we must learn how bacteria make and transport such complex molecules as well as understanding how we metabolise them. We will study how gut and mouth bacteria make SLs with world experts in America and Germany with a collaborator from the UK. We will begin with a study of the enzyme serine palmitoyltransferase (SPT) that uses two main building blocks - an amino acid called L-serine and a long chain fatty acid, to make the first SL intermediate. We will determine the 3D structure of the SPT in each bacterium and compare their shapes and evolution. Of special interest, the structure of the bacterial SLs is unusual and contains distinctive chemical fingerprints and we will investigate their origins by feeding the bacteria heavy versions of the proposed building blocks and tracking their incorporation. Nothing is known about how the microbiota makes unusual branched chain SLs so we will study enzymes that convert can branch-chain amino acids into specific building blocks. Bacteria contain ceramides with an unsusual inositol sugar so we will purify and characterise the enzyme myo-inositol phosphate synthase (MIPS) that uses glucose phosphate as a substrate. At the end of our study we will have begun to define the biosynthetic blueprint of the microbiota. Our results will be of interest to academic microbiologists and chemists as well as those interested in human health. Moreover, a number of drug and healthcare companies are also interested in the microbiome and they could use our knowledge to develop therapies that may have impact on disease and long term well being.

动物和细菌细胞有一个保护性的防水外壳，由亲水（亲水）的头部基团和长的憎水（疏水）的尾部分子组成。这个大家族的分子被称为脂质，包括饱和/不饱和脂肪和胆固醇等常见物质。一个特殊的脂质亚家族被称为鞘脂（SL）及其更复杂的神经酰胺版本（具有两个脂肪尾）。SL不仅在外壳中发挥结构性作用，使细胞膜能够抵抗水分，让营养物质进入并排出;它们还能够刺激人体免疫系统。SL水平是动态的，但也是严格控制的-细胞SL水平的任何增加或减少都是出问题的迹象。SL水平的变化与老年和阿尔茨海默氏症、糖尿病、哮喘、癌症和神经消耗性疾病等疾病密切相关。一个对人类健康有直接影响的令人兴奋的研究领域是发现人类是许多不同类型细菌的宿主-这些细菌统称为微生物群/微生物组。目前的估计是，我们体内的每一个人类细胞都有一个细菌细胞。这些细菌可能是“坏”的，会导致疾病（例如超级细菌），但大多数是“好”的细菌，对我们的健康有益。这些细菌生活在我们的口腔、皮肤和肠道中，帮助我们代谢食物，也被认为起着保护作用。一个令人惊讶的发现是，与我们生活在一起的细菌产生了允许细菌和人类细胞交流的分子。SL就是这样一个分子家族--人类细胞和细菌细胞都能制造相同的分子是非常不寻常的，这表明了某种进化上的联系。此外，据计算，我们的肠道中任何时候都有几克SL，它们对我们的健康做出了至关重要的贡献。最近的研究表明，微生物群与糖尿病、肥胖症和癌症等疾病有关。所有细胞都是通过使用简单的构建模块的多步途径来制造SL的--这些步骤由称为酶的分子机器催化（加速）。研究集中在参与人类SL生物合成的酶上，但对微生物群中的SL生物合成知之甚少。为了充分了解我们和细菌之间的关系，我们必须了解细菌如何制造和运输这些复杂的分子，以及了解我们如何代谢它们。我们将与来自美国和德国的世界专家以及来自英国的合作者一起研究肠道和口腔细菌是如何制造SL的。我们将开始与酶丝氨酸棕榈酰转移酶（SPT）的研究，使用两个主要的积木-一个氨基酸称为L-丝氨酸和长链脂肪酸，使第一SL中间体。我们将确定每种细菌中SPT的3D结构，并比较它们的形状和进化。特别有趣的是，细菌SL的结构是不寻常的，包含独特的化学指纹，我们将通过喂养细菌重版本的拟议构建模块并跟踪它们的掺入来研究它们的起源。关于微生物群如何制造不寻常的支链SL，我们一无所知，所以我们将研究将支链氨基酸转化为特定构建模块的酶。细菌中含有神经酰胺和一种不常见的肌醇，因此我们将纯化和纯化使用葡萄糖磷酸作为底物的肌醇磷酸合酶（MIPS）。在研究结束时，我们将开始定义微生物群的生物合成蓝图。我们的研究结果将引起学术微生物学家和化学家以及对人类健康感兴趣的人的兴趣。此外，许多制药和医疗保健公司也对微生物组感兴趣，他们可以利用我们的知识开发可能对疾病和长期健康产生影响的疗法。

项目成果

Characterization of inositol lipid metabolism in gut-associated Bacteroidetes.

• DOI: 10.1038/s41564-022-01152-6
• 发表时间: 2022-07
• 期刊: Nature microbiology
• 影响因子: 28.3