Processing of cell surface lipoproteins in Streptomyces coelicolor. A new paradigm?

天蓝色链霉菌细胞表面脂蛋白的加工。

基本信息

批准号：
BB/F009429/1
负责人：
Matthew Hutchings
金额：
$ 40.07万
依托单位：
University of East Anglia
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2007
资助国家：
英国
起止时间：
2007 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FF009429%2F1
关键词：
Processing cell surface lipoproteins Streptomyces

项目摘要

Bacteria can be divided into two main groups; Gram negative bacteria have two membranes surrounding the cell, the cytoplasmic membrane and the outer membrane. They also have a space between these membranes called the periplasm. Proteins which are exported across the cytoplasmic membrane typically end up in the periplasm. Gram positive bacteria have only a single membrane, surrounded by a thick cell wall. Proteins which are exported across the membrane must be anchored to the outer surface of the membrane, or the cell wall, to avoid being lost entirely from the cell. These cell surface proteins act as a point of contact with the outside world and are involved in a number of essential processes including sensing environmental changes, protein folding, respiration and nutrient scavenging. They also have an important role in surface attachment and are essential for successful host infection in disease-causing bacteria. One of the main ways in which bacteria attach proteins to their membranes is by attaching a lipid molecule to the N-terminal end of the protein. The widely accepted model suggests that these 'lipoproteins' are first targeted to the Sec (secretion) pathway by a signal sequence at the N-terminus of the protein. Sec transports them across the cytoplasmic membrane to the outside of the cell where an enzyme called Lgt attaches the lipid molecule. The signal sequence is then cleaved by an enzyme called Lsp. In Gram positive bacteria the pathway ends here and the proteins are attached to the outer face of the membrane. In Gram negative bacteria these proteins have another lipid molecule attached by an enzyme called Lnt and this allows them to be transported to the outer membrane. Only a small proportion is retained in the inner membrane. In Gram negative bacteria all the enzymes involved in lipoprotein biosynthesis are essential, probably because removing any one of them results in lipoproteins accumulating in, and destabilising, the inner membrane. In Gram positive bacteria they are essential for the virulence of many disease-causing organisms. They therefore represent an excellent target for new antibacterial drugs such as globomycin, a strong inhibitor of Lsp. We have been studying lipoprotein biosynthesis in the Gram positive bacterium Streptomyces coelicolor, and have discovered some surprising differences which could challenge the widely accepted model. Previously it was assumed that all lipoproteins were exported by Sec but this is not the case in S. coelicolor. We have good evidence that some S. coelicolor lipoproteins can be exported by the Tat secretion pathway. While Sec transports linear proteins, Tat is typically used to transport fully folded proteins which are assembled inside the cell. This challenges the current model and it also suggests that the Lgt enzyme can attach lipids to both linear and fully folded proteins. S. coelicolor is unusual in that it contains two Lgt enzymes and it is possible that one acts on Sec-, and the other on Tat-dependent lipoproteins. Finally, and perhaps most puzzlingly of all, S. coelicolor contains two Lnt enzymes. This enzyme performs a step previously thought to be unique to Gram negative bacteria. Since Gram positive bacteria do not have an outer membrane the function of these enzymes in S. coelicolor are unclear. In this study we will investigate the differences in the export and modification of Tat- and Sec-dependent lipoproteins. We will examine the functions of the two Lgt enzymes in these processing pathways. We will also test the activities of the Lnt enzymes to see if they have the same function as Lnt in Gram negative bacteria. We anticipate that the results of this study will lead to a paradigm shift in our understanding of bacterial lipoprotein biosynthesis.

细菌可以分为两个主要组。革兰氏阴性细菌在细胞周围有两个膜，细胞质膜和外膜。它们在这些称为Pariplasm的膜之间也有一个空间。在细胞质膜上输出的蛋白质通常会在周期呈周围。革兰氏阳性细菌只有一个膜，周围是厚细胞壁。在整个膜上导出的蛋白质必须锚定在膜的外表面或细胞壁的外表面，以免完全从细胞中丢失。这些细胞表面蛋白是与外界接触的点，并参与了许多基本过程，包括感应环境变化，蛋白质折叠，呼吸和营养清除。它们在表面附着中也具有重要作用，对于成功的宿主感染是引起疾病的细菌的重要作用。细菌将蛋白连接到其膜上的主要方法之一是将脂质分子连接到蛋白质的N末端。广泛接受的模型表明，这些“脂蛋白”首先是通过蛋白质N末端的信号序列靶向SEC（分泌）途径的。 SEC将它们跨过细胞质膜转移到细胞的外部，该酶称为LGT连接脂质分子。然后通过称为LSP的酶裂解信号序列。在克阳性细菌中，途径在这里结束，蛋白质附着在膜的外表面上。在革兰氏阴性细菌中，这些蛋白质具有另一个由称为LNT的酶附着的脂质分子，这使它们可以将其转运到外膜。在内膜中只保留了一小部分。在革兰氏阴性细菌中，所有参与脂蛋白生物合成的酶都是必不可少的，这可能是因为去除其中任何一种酶会导致脂蛋白积聚并破坏稳定的内膜。在克阳性细菌中，它们对于许多引起疾病的生物的毒力至关重要。因此，它们代表了新型抗菌药物（例如Globomycin）的绝佳靶标，Globomycin是LSP的强抑制剂。我们一直在研究革兰氏阳性细菌Coelicolor中的脂蛋白生物合成，并发现了一些令人惊讶的差异，这些差异可能会挑战广泛接受的模型。以前假定所有脂蛋白都是由SEC出口的，但在塞氏菌中并非如此。我们有充分的证据表明，某些Coelicolor脂蛋白可以通过TAT分泌途径导出。 SEC转运线性蛋白时，TAT通常用于运输组装在电池内部的完全折叠蛋白。这挑战了当前模型，还表明LGT酶可以将脂质连接到线性和完全折叠的蛋白质上。 S. coelicolor是不寻常的，因为它含有两个LGT酶，并且一种可能作用于Sec-，另一个对TAT依赖性脂蛋白作用。最后，也许最令人困惑的是，Coelicolor含有两个LNT酶。该酶执行以前认为是革兰氏阴性细菌独有的一步。由于革兰氏阳性细菌没有外膜，因此尚不清楚这些酶在卵链球葡萄球菌中的功能。在这项研究中，我们将研究TAT和SEC依赖性脂蛋白的出口和修饰的差异。我们将检查这些处理途径中两种LGT酶的功能。我们还将测试LNT酶的活性，以查看它们在革兰氏阴性细菌中的功能是否与LNT相同。我们预计这项研究的结果将导致我们对细菌脂蛋白生物合成的理解的范式转移。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Mammalian cell entry genes in Streptomyces may provide clues to the evolution of bacterial virulence.

DOI：
10.1038/srep01109
发表时间：
2013
期刊：
SCIENTIFIC REPORTS
影响因子：
4.6
作者：
Clark, Laura C.;Seipke, Ryan F.;Prieto, Pilar;Willemse, Joost;van Wezel, Gilles P.;Hutchings, Matthew I.;Hoskisson, Paul A.
通讯作者：
Hoskisson, Paul A.

Cosmid based mutagenesis causes genetic instability in Streptomyces coelicolor, as shown by targeting of the lipoprotein signal peptidase gene.

DOI：
10.1038/srep29495
发表时间：
2016-07-12
期刊：
Scientific reports
影响因子：
4.6
作者：
Munnoch JT;Widdick DA;Chandra G;Sutcliffe IC;Palmer T;Hutchings MI
通讯作者：
Hutchings MI

The transcriptional repressor protein NsrR senses nitric oxide directly via a [2Fe-2S] cluster.

DOI：
10.1371/journal.pone.0003623
发表时间：
2008
期刊：
PloS one
影响因子：
3.7
作者：
Tucker NP;Hicks MG;Clarke TA;Crack JC;Chandra G;Le Brun NE;Dixon R;Hutchings MI
通讯作者：
Hutchings MI

Cosmid based mutagenesis causes genetic instability in Streptomyces coelicolor , as shown by targeting of the lipoprotein signal peptidase gene

基于粘粒的诱变导致天蓝色链霉菌遗传不稳定，如脂蛋白信号肽酶基因靶向所示。