Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily
Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily
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DOI：
10.1046/j.1365-2958.2003.03619.x
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发表时间：
2003-08-01
影响因子：
3.6
通讯作者：
Albert, KI
中科院分区：
文献类型：
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作者：
Matsunaga, J;Barocchi, MA;Albert, KI
具有细菌免疫球蛋白样（Big）结构域的蛋白质，例如假结核耶尔森氏菌侵袭素和大肠杆菌紧密蛋白，是介导宿主哺乳动物细胞侵袭或附着的表面表达蛋白。在这里，我们报告了一个新的家庭的大结构域蛋白质，称为Lig（钩端螺旋体Ig样）蛋白质，在致病性钩端螺旋体的鉴定和表征。筛选L. interrogans和L.用来自钩端螺旋体病患者的血清的kirschneri表达文库鉴定了13个λ噬菌体克隆，其编码90个氨基酸Big结构域的串联重复序列。两个无花果基因，命名为ligA和ligB，和一个假基因，ligC，进行了鉴定。ligA和ligB基因编码氨基末端脂蛋白信号肽，随后是10或11个Big结构域重复序列，并且在ligB的情况下，是独特的羧基末端非重复序列结构域。ligC的结构与ligB相似，但含有破坏阅读框架的突变。fig序列存在于致病性但非致病性钩端螺旋体物种中。LigA和LigB由多种毒性钩端螺旋体菌株表达。Lig蛋白和RNA转录本表达的丧失与致病菌株培养减毒期间观察到的毒力丧失相关。高压冷冻置换，免疫细胞化学电子显微镜证实，Lig蛋白定位于细菌表面。用患者血清进行的免疫印迹研究发现，Lig蛋白是在急性宿主感染期间识别的主要抗原。这些观察结果表明，Lig蛋白是一种新鉴定的致病性钩端螺旋体的表面蛋白，其通过类比其他细菌免疫球蛋白超家族毒力因子，可能在钩端螺旋体发病过程中的宿主细胞附着和侵袭中发挥作用。
Proteins with bacterial immunoglobulin-like (Big) domains, such as the Yersinia pseudotuberculosis invasin and Escherichia coli intimin, are surface-expressed proteins that mediate host mammalian cell invasion or attachment. Here, we report the identification and characterization of a new family of Big domain proteins, referred to as Lig (leptospiral Ig-like) proteins, in pathogenic Leptospira. Screening of L. interrogans and L. kirschneri expression libraries with sera from leptospirosis patients identified 13 lambda phage clones that encode tandem repeats of the 90 amino acid Big domain. Two fig genes, designated ligA and ligB, and one pseudogene, ligC, were identified. The ligA and ligB genes encode amino-terminal lipoprotein signal peptides followed by 10 or 11 Big domain repeats and, in the case of ligB, a unique carboxy-terminal non-repeat domain. The organization of ligC is similar to that of ligB but contains mutations that disrupt the reading frame. The fig sequences are present in pathogenic but not saprophytic Leptospira species. LigA and LigB are expressed by a variety of virulent leptospiral strains. Loss of Lig protein and RNA transcript expression is correlated with the observed loss of virulence during culture attenuation of pathogenic strains. High-pressure freeze substitution followed by immunocytochemical electron microscopy confirmed that the Lig proteins were localized to the bacterial surface. Immunoblot studies with patient sera found that the Lig proteins are a major antigen recognized during the acute host infection. These observations demonstrate that the Lig proteins are a newly identified surface protein of pathogenic Leptospira, which by analogy to other bacterial immunoglobulin superfamily virulence factors, may play a role in host cell attachment and invasion during leptospiral pathogenesis.