Identification of a Large Family of Slam-Dependent Surface Lipoproteins in Gram-Negative Bacteria.
Identification of a Large Family of Slam-Dependent Surface Lipoproteins in Gram-Negative Bacteria.
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DOI：
10.3389/fcimb.2017.00207
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发表时间：
2017
影响因子：
5.7
通讯作者：
Moraes TF
中科院分区：
文献类型：
--
作者：
Hooda Y;Lai CCL;Moraes TF
许多革兰氏阴性细菌的表面装饰有通过酰化的N-末端锚定到外膜的可溶性蛋白质;这些蛋白质被称为表面脂蛋白或SLP。在脑膜炎奈瑟氏菌中，SLP如转铁蛋白结合蛋白B（Tbp B）和因子H结合蛋白（fHbp）对于宿主定植和感染是必需的，因为它们分别在铁获得和免疫逃避中起重要作用。最近，我们确定了一个家庭的外膜蛋白称为Slam（表面脂蛋白组装调制器），是必不可少的表面展示奈瑟球菌SLP。在本研究中，我们进行了生物信息学分析，以确定在638个革兰氏阴性细菌物种的832个Slam相关序列。该清单包括几种已知的人类病原体，其中许多以前没有报道过具有SLP。假设编码Slam的SLP底物的基因可能存在于与Slam基因相同的基因簇中，我们手动策划了353个推定的Slam同源物的相邻基因。从我们的分析中，我们发现，185（~52%）的353个假定的Slam同源物位于邻近的基因编码的蛋白质与N-末端脂盒基序。该列表包括编码先前报告的流感嗜血杆菌和卡他莫拉菌中的SLP的基因，我们能够证明相邻的SLAM是必要的，并且足以在大肠杆菌表面上展示这些脂蛋白。为了进一步验证预测的SLP列表的真实性，我们测试了来自人畜共患病原体多杀性巴氏杆菌的一种这样的Slam邻近蛋白的表面展示。在E.大肠杆菌易位试验表明，该蛋白是一个依赖于Slam的SLP。基于多重序列比对和结构域注释，我们发现一个八链的β-桶结构域是共同的所有预测的Slam依赖性SLP。这些发现表明，具有TbpB样折叠的SLP广泛存在于变形菌中，它们与它们的相互作用伴侣Slam一起存在。将来，可以研究在致病菌中发现的SLP在毒力中的作用，也可以作为疫苗开发的候选物。
The surfaces of many Gram-negative bacteria are decorated with soluble proteins anchored to the outer membrane via an acylated N-terminus; these proteins are referred to as surface lipoproteins or SLPs. In Neisseria meningitidis, SLPs such as transferrin-binding protein B (TbpB) and factor-H binding protein (fHbp) are essential for host colonization and infection because of their essential roles in iron acquisition and immune evasion, respectively. Recently, we identified a family of outer membrane proteins called Slam (Surface lipoprotein assembly modulator) that are essential for surface display of neisserial SLPs. In the present study, we performed a bioinformatics analysis to identify 832 Slam related sequences in 638 Gram-negative bacterial species. The list included several known human pathogens, many of which were not previously reported to possess SLPs. Hypothesizing that genes encoding SLP substrates of Slams may be present in the same gene cluster as the Slam genes, we manually curated neighboring genes for 353 putative Slam homologs. From our analysis, we found that 185 (~52%) of the 353 putative Slam homologs are located adjacent to genes that encode a protein with an N-terminal lipobox motif. This list included genes encoding previously reported SLPs in Haemophilus influenzae and Moraxella catarrhalis, for which we were able to show that the neighboring Slams are necessary and sufficient to display these lipoproteins on the surface of Escherichia coli. To further verify the authenticity of the list of predicted SLPs, we tested the surface display of one such Slam-adjacent protein from Pasteurella multocida, a zoonotic pathogen. A robust Slam-dependent display of the P. multocida protein was observed in the E. coli translocation assay indicating that the protein is a Slam-dependent SLP. Based on multiple sequence alignments and domain annotations, we found that an eight-stranded beta-barrel domain is common to all the predicted Slam-dependent SLPs. These findings suggest that SLPs with a TbpB-like fold are found widely in Proteobacteria where they exist with their interaction partner Slam. In the future, SLPs found in pathogenic bacteria can be investigated for their role in virulence and may also serve as candidates for vaccine development.