Comprehensive Spatial Analysis of the Borrelia burgdorferi Lipoproteome Reveals a Compartmentalization Bias toward the Bacterial Surface
Comprehensive Spatial Analysis of the Borrelia burgdorferi Lipoproteome Reveals a Compartmentalization Bias toward the Bacterial Surface
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DOI：
10.1128/jb.00658-16
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发表时间：
2017-03-01
影响因子：
3.2
通讯作者：
Zuckert, Wolfram R.
中科院分区：
文献类型：
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作者：
Dowdell, Alexander S.;Murphy, Maxwell D.;Zuckert, Wolfram R.
莱姆病螺旋体伯氏疏螺旋体在细菌中是独一无二的，因为它含有大量脂蛋白，这些脂蛋白由一个小的、异常片段化的且主要是线性的基因组编码。这些脂蛋白在外周锚定在内膜或外膜上，面对周质或外部环境，承担不同的作用。一个突出的子集的脂蛋白作为明显的关键环节的地方性蜱脊椎动物感染周期已被探索作为疫苗的目标。然而，大多数的B。Burgdorferi脂蛋白质组仍然没有特征。在这里，我们全面和决定性地定位了B。通过将已建立的蛋白定位测定应用于新产生的表位标记的脂蛋白表达文库，并通过使用灵敏的全局质谱法验证所获得的单个蛋白定位结果，来对伯氏菌脂蛋白组进行分析。推导出的共识定位数据表明，86的125个分析的脂蛋白编码的B。Burgdorferi分泌到细菌表面。其余39种周质脂蛋白中的31种保留在内膜中，只有8种脂蛋白锚定在外膜的周质小叶中。对10种脂蛋白的定位进行了进一步的定义或修正，并对52种表面脂蛋白和23种周质脂蛋白进行了新的定位。交叉引用以前的研究表明，疏螺旋体表面脂蛋白质组有助于宿主病原体接口主要是由质粒编码。相反，周质脂蛋白主要由染色体位点编码。这些研究填补了我们对一种重要的人类病原体的功能性脂蛋白组的理解的空白，并为更深入地研究被忽视的螺旋体脂蛋白奠定了基础。重要性莱姆病螺旋体伯氏疏螺旋体的小而异常片段化的基因组编码超过120种脂蛋白。该领域的研究主要集中在相对较少的表面脂蛋白上，这些脂蛋白在这种全球性人类病原体的传播和发病机制中发挥重要作用。然而，一个全面的空间评估整个疏螺旋体脂蛋白组一直失踪。目前的研究新确定了52个表面和23个周质脂蛋白。总的来说，三分之二的B。Burgdorferi脂蛋白定位于表面，而面向周质的外膜脂蛋白是罕见的。该分析强调了脂蛋白对螺旋体相当复杂和适应性强的宿主-病原体界面的主导贡献，并鼓励对其脂蛋白组进行进一步的功能探索。
The Lyme disease spirochete Borrelia burgdorferi is unique among bacteria in its large number of lipoproteins that are encoded by a small, exceptionally fragmented, and predominantly linear genome. Peripherally anchored in either the inner or outer membrane and facing either the periplasm or the external environment, these lipoproteins assume varied roles. A prominent subset of lipoproteins functioning as the apparent linchpins of the enzootic tick-vertebrate infection cycle have been explored as vaccine targets. Yet, most of the B. burgdorferi lipoproteome has remained uncharacterized. Here, we comprehensively and conclusively localize the B. burgdorferi lipoproteome by applying established protein localization assays to a newly generated epitope-tagged lipoprotein expression library and by validating the obtained individual protein localization results using a sensitive global mass spectrometry approach. The derived consensus localization data indicate that 86 of the 125 analyzed lipoproteins encoded by B. burgdorferi are secreted to the bacterial surface. Thirty-one of the remaining 39 periplasmic lipoproteins are retained in the inner membrane, with only 8 lipoproteins being anchored in the periplasmic leaflet of the outer membrane. The localization of 10 lipoproteins was further defined or revised, and 52 surface and 23 periplasmic lipoproteins were newly localized. Cross-referencing prior studies revealed that the borrelial surface lipoproteome contributing to the hostpathogen interface is encoded predominantly by plasmids. Conversely, periplasmic lipoproteins are encoded mainly by chromosomal loci. These studies close a gap in our understanding of the functional lipoproteome of an important human pathogen and set the stage for more in-depth studies of thus-far-neglected spirochetal lipoproteins. IMPORTANCE The small and exceptionally fragmented genome of the Lyme disease spirochete Borrelia burgdorferi encodes over 120 lipoproteins. Studies in the field have predominantly focused on a relatively small number of surface lipoproteins that play important roles in the transmission and pathogenesis of this global human pathogen. Yet, a comprehensive spatial assessment of the entire borrelial lipoproteome has been missing. The current study newly identifies 52 surface and 23 periplasmic lipoproteins. Overall, two-thirds of the B. burgdorferi lipoproteins localize to the surface, while outer membrane lipoproteins facing the periplasm are rare. This analysis underscores the dominant contribution of lipoproteins to the spirochete's rather complex and adaptable host-pathogen interface, and it encourages further functional exploration of its lipoproteome.