RESUMEN
When grown in the presence of exogenous collagen I, Mycobacterium bovis BCG was shown to form clumps. Scanning electron microscopy examination of these clumps revealed the presence of collagen fibres cross-linking the bacilli. Since collagen is a major constituent of the eukaryotic extracellular matrices, we assayed BCG cytoadherence in the presence of exogenous collagen I. Collagen increased the interaction of the bacilli with A549 type II pneumocytes or U937 macrophages, suggesting that BCG is able to recruit collagen to facilitate its attachment to host cells. Using an affinity chromatography approach, we have isolated a BCG collagen-binding protein corresponding to the previously described mycobacterial laminin-binding histone-like protein (LBP/Hlp), a highly conserved protein associated with the mycobacterial cell wall. Moreover, Mycobacterium leprae LBP/Hlp, a well-characterized adhesin, was also able to bind collagen I. Finally, using recombinant fragments of M. leprae LBP/Hlp, we mapped the collagen-binding activity within the C-terminal domain of the adhesin. Since this protein was already shown to be involved in the recognition of laminin and heparan sulphate-containing proteoglycans, the present observations reinforce the adhesive activities of LBP/Hlp, which can be therefore considered as a multifaceted mycobacterial adhesin, playing an important role in both leprosy and tuberculosis pathogenesis.
Asunto(s)
Adhesión Bacteriana , Colágeno Tipo I/farmacología , Mycobacterium bovis/metabolismo , Mycobacterium leprae/metabolismo , Animales , Adhesión Bacteriana/inmunología , Proteínas Portadoras/inmunología , Proteínas Portadoras/metabolismo , Colágeno Tipo I/metabolismo , Histonas/metabolismo , Humanos , Mycobacterium bovis/inmunología , Mycobacterium leprae/inmunologíaRESUMEN
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.
Asunto(s)
Adhesinas Bacterianas/metabolismo , Proteínas Bacterianas/metabolismo , Laminina/metabolismo , Proteínas de la Membrana/metabolismo , Mycobacterium leprae/fisiología , Mapeo de Interacción de Proteínas , Adhesinas Bacterianas/química , Adhesinas Bacterianas/genética , Adhesión Bacteriana , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Línea Celular , Expresión Génica , Heparina/metabolismo , Heparitina Sulfato/metabolismo , Humanos , Laminina/genética , Proteínas de la Membrana/síntesis química , Proteínas de la Membrana/genética , Estructura Terciaria de Proteína , Células de Schwann/microbiología , Eliminación de SecuenciaRESUMEN
More than one century after the discovery of their etiological agents, tuberculosis and leprosy remain as major health threats for humans, and the molecular mechanisms that lead to the development of both diseases are poorly understood. The elucidation of these mechanisms, and especially those allowing for the mycobacteria to systemically disseminate, should facilitate the development of new prophylactic and/or therapeutic strategies. This review is focused on the routes that Mycobacterium tuberculosis and Mycobacterium leprae may use to disseminate within the human body, and the potential roles played by recently characterized adhesins in this process.
Asunto(s)
Adhesinas Bacterianas/fisiología , Lepra/microbiología , Mycobacterium leprae/patogenicidad , Mycobacterium tuberculosis/patogenicidad , Tuberculosis/microbiología , Humanos , Lepra/patología , Mycobacterium leprae/ultraestructura , Mycobacterium tuberculosis/ultraestructura , Tuberculosis/patologíaRESUMEN
When grown in the presence of exogenous collagen I, Mycobacterium bovis BCG was shown to form clumps. Scanning electron microscopy examination of these clumps revealed the presence of collagen fibres cross-linking the bacilli. Since collagen is a major constituent of the eukaryotic extracellular matrices, we assayed BCG cytoadherence in the presence of exogenous collagen I. Collagen increased the interaction of the bacilli with A549 type II pneumocytes or U937 macrophages, suggesting that BCG is able to recruit collagen to facilitate its attachment to host cells. Using an affinity chromatography approach, we have isolated a BCG collagen-binding protein corresponding to the previously described mycobacterial laminin-binding histone-like protein (LBP/Hlp), a highly conserved protein associated with the mycobacterial cell wall. Moreover, Mycobacterium leprae LBP/Hlp, a well-characterized adhesin, was also able to bind collagen I. Finally, using recombinant fragments of M. leprae LBP/Hlp, we mapped the collagen-binding activity within the C-terminal domain of the adhesin. Since this protein was already shown to be involved in the recognition of laminin and heparan sulphate-containing proteoglycans, the present observations reinforce the adhesive activities of LBP/Hlp, which can be therefore considered as a multifaceted mycobacterial adhesin, playing an important role in both leprosy and tuberculosis pathogenesis.
Asunto(s)
Animales , Humanos , Adhesión Bacteriana , Colágeno Tipo I/farmacología , Mycobacterium bovis/metabolismo , Mycobacterium leprae/metabolismo , Adhesión Bacteriana/inmunología , Proteínas Portadoras/inmunología , Proteínas Portadoras/metabolismo , Colágeno Tipo I/metabolismo , Histonas/metabolismo , Mycobacterium bovis/inmunología , Mycobacterium leprae/inmunologíaRESUMEN
More than one century after the discovery of their etiological agents, tuberculosis and leprosy remain as major health threats for humans, and the molecular mechanisms that lead to the development of both diseases are poorly understood. The elucidation of these mechanisms, and especially those allowing for the mycobacteria to systemically disseminate, should facilitate the development of new prophylactic and/or therapeutic strategies. This review is focused on the routes that Mycobacterium tuberculosis and Mycobacterium leprae may use to disseminate within the human body, and the potential roles played by recently characterized adhesins in this process.