Identification of iron and heme utilization genes in Aeromonas and their role in the colonization of the leech digestive tract
Molecular microbiology published in Front Microbiol (2015)
Abstract
It is known that many pathogens produce high-affinity iron uptake systems like siderophores and/or proteins for utilizing iron bound to heme-containing molecules, which facilitate iron-acquisition inside a host. In mutualistic digestive-tract associations, iron uptake systems have not been as well studied. We investigated the importance of two iron utilization systems within the beneficial digestive-tract association Aeromonas veronii and the medicinal leech, Hirudo verbana. Siderophores were detected in A. veronii using chrome azurol S. Using a mini Tn5, a transposon insertion in viuB generated a mutant unable to utilize iron using siderophores. The A. veronii genome was then searched for genes potentially involved in iron utilization bound to heme-containing molecules. A putative outer membrane heme receptor (hgpB) was identified with a transcriptional activator, termed hgpR, downstream. The hgpB gene was interrupted with an antibiotic resistance cassette in both the parent strain and the viuB mutant, yielding an hgpB mutant and a mutant with both iron uptake systems inactivated. In vitro assays indicated that hgpB is involved in utilizing iron bound to heme and that both iron utilization systems are important for A. veronii to grow in blood. In vivo colonization assays revealed that the ability to acquire iron from heme-containing molecules is critical for A. veronii to colonize the leech gut. Since iron and specifically heme utilization is important in this mutualistic relationship and has a potential role in virulence factor of other organisms, genomes from different Aeromonas strains (both clinical and environmental) were queried with iron utilization genes of A. veronii. This analysis revealed that in contrast to the siderophore utilization genes heme utilization genes are widely distributed among aeromonads. The importance of heme utilization in the colonization of the leech further confirms that symbiotic and pathogenic relationships possess similar mechanisms for interacting with animal hosts.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Aeromonas veronii requires both siderophore-mediated iron uptake (viuB) and heme utilization (hgpB) to grow in blood and to colonize the leech gut. Heme utilization genes are widely distributed across Aeromonas strains.
Por qué esto importa para la hirudoterapia
Este estudio investigó dos sistemas de utilización de hierro en Aeromonas veronii —la captación basada en sideróforos y un putativo receptor de hemo (hgpB)— y su papel en la colonización del tracto digestivo de la sanguijuela medicinal Hirudo verbana. Mediante mutagénesis por transposón y ensayos de colonización in vivo, los autores encontraron que la capacidad de adquirir hierro a partir de moléculas que contienen hemo es crítica para la colonización intestinal de A. veronii y que los genes de utilización de hemo están ampliamente distribuidos entre los aeromonadales. El trabajo tiene una relevancia tangencial para el dominio de ASH porque concierne a la ecología microbiana del intestino de la sanguijuela medicinal, pero examina la genética bacteriana, no el secretoma de la sanguijuela, la alimentación de la sanguijuela, la fisiología digestiva ni ninguna aplicación terapéutica. La relevancia del estudio para la práctica de la hirudoterapia es, en el mejor de los casos, indirecta.
Citación
Identification of iron and heme utilization genes in Aeromonas and their role in the colonization of the leech digestive tract.
Maltz M, LeVarge BL, Graf J · Frontiers in microbiology, 2015
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Añadido a la biblioteca ASH: May 26, 2026 · Última actualización del sitio: 18 de junio de 2026