The type II secretion system is essential for erythrocyte lysis and gut colonization by the leech digestive tract symbiont Aeromonas veronii
Basic science / microbiology published in Appl Environ Microbiol (2011)
Abstract
Hemolysin and the type II secretion system (T2SS) have been shown to be important for virulence in many pathogens, but very few studies have shown their importance in beneficial microbes. Here, we investigated the importance of the type II secretion pathway in the beneficial digestive-tract association of Aeromonas veronii and the medicinal leech Hirudo verbana and revealed a critical role for the hemolysis of erythrocytes. A mutant with a miniTn5 insertion in exeM, which is involved in forming the inner membrane platform in the T2SS, was isolated by screening mutants for loss of hemolysis on blood agar plates. A hemolysis assay was used to quantify the mutant's deficiency in lysing sheep erythrocytes and revealed a 99.9% decrease compared to the parent strain. The importance of the T2SS in the colonization of the symbiotic host was assessed. Colonization assays revealed that the T2SS is critical for initial colonization of the leech gut. The defect was tied to the loss of hemolysin production by performing a colonization assay with blood containing lysed erythrocytes. This restored the colonization defect in the mutant. Complementation of the mutant using the promoter region and exeMN revealed that the T2SS is responsible for secreting hemolysin into the extracellular space and that both the T2SS and hemolysin export by the T2SS are critical for initial establishment of A. veronii in the leech gut.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Mutagenesis study identifying the type II secretion system (T2SS) and hemolysin export as critical for erythrocyte lysis and gut colonization of medicinal leeches by Aeromonas veronii. exeM mutants showed 99.9% reduction in hemolysis.
Por qué esto importa para la hirudoterapia
Este estudio investigó el papel del sistema de secreción de tipo II (T2SS) en la asociación beneficiosa del tracto digestivo entre Aeromonas veronii y la sanguijuela medicinal Hirudo verbana. Un mutante con un componente del T2SS interrumpido (exeM) mostró una reducción del 99,9 % en la hemólisis de eritrocitos de oveja y un defecto de colonización en el intestino de la sanguijuela; este defecto se rescató cuando el mutante fue alimentado con sangre que contenía eritrocitos pre-lisados. La complementación con exeMN restauró la secreción de hemolisina y la colonización, confirmando que la exportación de hemolisina mediada por T2SS es crítica para el establecimiento inicial de A. veronii en el intestino de la sanguijuela. Para el ámbito de ASH, esto contribuye a comprender la biología del tracto digestivo de la sanguijuela medicinal y sus asociaciones simbióticas. La salvedad es que se trata de un estudio básico de microbiología en un modelo de sanguijuela sin hirudoterapia directa, secretoma ni aplicación clínica, y no aborda los desenlaces de la terapia con sanguijuelas.
Citación
The type II secretion system is essential for erythrocyte lysis and gut colonization by the leech digestive tract symbiont Aeromonas veronii.
Maltz M et al. · Applied and environmental microbiology, 2011
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Añadido a la biblioteca ASH: May 27, 2026 · Última actualización del sitio: 18 de junio de 2026