Soares de Lima Cristiana, Zulianello Laurence, Marques Maria Angela de Melo, Kim Heejin, Portugal Michelle Iespa, Antunes Sérgio Luiz, Menozzi Franco Dante, Ottenhoff Tom Henricus Maria, Brennan Patrick Joseph, Pessolani Maria Cristina Vidal
Laboratory of Cellular Microbiology, Instituto Oswaldo Cruz, Fiocruz, RJ 21045-900, Brazil.
Microbes Infect. 2005 Jul;7(9-10):1097-109. doi: 10.1016/j.micinf.2005.02.013.
Binding of Mycobacterium leprae to and invasion of Schwann cells (SC) represent a crucial step that initiates nerve damage in leprosy. We and others have described that M. leprae colonization of the peripheral nerve system may be mediated in part by a surface-exposed histone-like protein (Hlp), characterized as a laminin-binding protein (LBP). Hlp/LBP has also been shown to play a role in the binding of mycobacteria to alveolar epithelial cells and macrophages. In the present study we report that M. leprae expresses Hlp/LBP protein during the course of human infection. Additionally, we analyzed the interaction of Hlp/LBP with the extracellular matrix and host cell surface. We show that Hlp/LBP, besides laminin, also binds heparin and heparan sulfate. Testing truncated recombinant Hlp molecules corresponding to the N-terminal (rHlp-N) and the C-terminal (rHlp-C) domains of the protein, we established that interaction of Hlp/LBP with laminin-2 and heparin is mainly mediated by the C-terminal domain of the protein. Moreover, the same domain was found to be involved in Hlp/LBP-mediating bacterial binding to human SC. Finally, evidence is shown suggesting that M. leprae produces a post-translationally modified Hlp/LBP containing methyllysine residues. Methylation of the lysine residues, however, seems not to affect the adhesive properties of Hlp/LBP. Taken together, our observations reinforce the involvement of Hlp/LBP as an adhesin in mycobacterial infections and define its highly positive C-terminal region as the major adhesive domain of this protein.
麻风分枝杆菌与施万细胞（SC）的结合及侵入是引发麻风病神经损伤的关键步骤。我们和其他人已经描述过，外周神经系统中麻风分枝杆菌的定植可能部分由一种表面暴露的组蛋白样蛋白（Hlp）介导，该蛋白被鉴定为层粘连蛋白结合蛋白（LBP）。Hlp/LBP也已被证明在分枝杆菌与肺泡上皮细胞和巨噬细胞的结合中起作用。在本研究中，我们报告麻风分枝杆菌在人类感染过程中表达Hlp/LBP蛋白。此外，我们分析了Hlp/LBP与细胞外基质和宿主细胞表面的相互作用。我们发现，除了层粘连蛋白外，Hlp/LBP还与肝素和硫酸乙酰肝素结合。通过测试与该蛋白的N端（rHlp-N）和C端（rHlp-C）结构域相对应的截短重组Hlp分子，我们确定Hlp/LBP与层粘连蛋白-2和肝素的相互作用主要由该蛋白的C端结构域介导。此外，发现同一结构域参与Hlp/LBP介导的细菌与人SC的结合。最后，有证据表明麻风分枝杆菌产生一种含有甲基赖氨酸残基的翻译后修饰的Hlp/LBP。然而，赖氨酸残基的甲基化似乎不影响Hlp/LBP的黏附特性。综上所述，我们的观察结果强化了Hlp/LBP作为一种黏附素在分枝杆菌感染中的作用，并将其高度阳性的C端区域定义为该蛋白的主要黏附结构域。
