Pathogenic Leptospira Evolved a Unique Gene Family Comprised of Ricin B-Like Lectin Domain-Containing Cytotoxins.
Pathogenic Leptospira Evolved a Unique Gene Family Comprised of Ricin B-Like Lectin Domain-Containing Cytotoxins.
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DOI：
10.3389/fmicb.2022.859680
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发表时间：
2022
影响因子：
5.2
通讯作者：
中科院分区：
文献类型：
--
作者：
钩端螺旋体病是一种全球重要的被忽视的人畜共患疾病。先前的数据表明，毒力修饰（VM）蛋白家族（PF07598）是I群致病性钩端螺旋体的一个显著特征，它进化为重要的毒力决定因素。在这里，我们证明了一种这样的VM蛋白LA3490（也称为Q8F0K3）是由疑问钩端螺旋体血清型Lai表达的，作为一种分泌的基因毒素，对人类细胞具有强大的细胞毒性。利用Phyre2进行结构同源性研究表明，VM蛋白是一种新型r型凝集素，含有串联n端蓖麻毒素b链样β-三叶结构域。重组LA3490 （rLA3490）和一个n端片段t3490，只含有预测的蓖麻蛋白B结构域，与末端半乳糖和n-乙酰半乳糖胺残基asialofetuin结合，直接与重组蓖麻蛋白B链竞争asialofetuin结合位点。单独使用t3490足以与固定化的异甲流蛋白和HeLa细胞表面结合，但既不内化也不具有细胞毒性。用rLA3490处理HeLa细胞导致细胞骨架解体、caspase-3激活和核断裂，并迅速导致细胞死亡。rLA3490对哺乳动物和细菌质粒DNA具有DNA酶活性。细胞表面结合、内化、核易位和dna酶功能的结合表明，LA3490和其他VM蛋白进化为细菌AB结构域毒素范式的新形式。
Leptospirosis is a globally important neglected zoonotic disease. Previous data suggest that a family of virulence-modifying (VM) proteins (PF07598) is a distinctive feature of group I pathogenic Leptospira that evolved as important virulence determinants. Here, we show that one such VM protein, LA3490 (also known as Q8F0K3), is expressed by Leptospira interrogans serovar Lai, as a secreted genotoxin that is potently cytotoxic to human cells. Structural homology searches using Phyre2 suggested that VM proteins are novel R-type lectins containing tandem N-terminal ricin B-chain-like β-trefoil domains. Recombinant LA3490 (rLA3490) and an N-terminal fragment, t3490, containing only the predicted ricin B domain, bound to the terminal galactose and N-acetyl-galactosamine residues, asialofetuin, and directly competed for asialofetuin-binding sites with recombinant ricin B chain. t3490 alone was sufficient for binding, both to immobilized asialofetuin and to the HeLa cell surface but was neither internalized nor cytotoxic. Treatment of HeLa cells with rLA3490 led to cytoskeleton disassembly, caspase-3 activation, and nuclear fragmentation, and was rapidly cytolethal. rLA3490 had DNase activity on mammalian and bacterial plasmid DNA. The combination of cell surface binding, internalization, nuclear translocation, and DNase functions indicate that LA3490 and other VM proteins evolved as novel forms of the bacterial AB domain-containing toxin paradigm.
影响因子：
4.6
作者：
Perpich JD;Kalia A;Price CTD;Jones SC;Wong K;Gehring K;Kwaik YA
通讯作者：
Kwaik YA