The evolution of three siderophore biosynthetic clusters in environmental and host-associating strains of Pantoea
For many pathogenic members of the Enterobacterales, siderophores play an important role in virulence, yet the siderophores of the host-associating members of the genus Pantoea remain unexplored. We conducted a genome-wide survey of environmental and host-associating strains of Pantoea to identify known and candidate siderophore biosynthetic clusters. Our analysis identified three clusters homologous to those of enterobactin, desferrioxamine, and aerobactin that were prevalent among Pantoea species. Using both phylogenetic and comparative genomic approaches, we demonstrate that the enterobactin-like cluster was present in the common ancestor of all Pantoea, with evidence for three independent losses of the cluster in P. eucalypti, P. eucrina, and the P. ananatis—P. stewartii lineage. The desferrioxamine biosynthetic cluster, previously described and characterized in Pantoea, was horizontally acquired from its close relative Erwinia, with phylogenetic evidence that these transfer events were ancient and occurred between ancestral lineages. The aerobactin cluster was identified in three host-associating species groups, P. septica, P. ananatis, and P. stewartii, with strong evidence for horizontal acquisition from human-pathogenic members of the Enterobacterales. Our work identifies and describes the key siderophore clusters in Pantoea, shows three distinct evolutionary processes driving their diversification, and provides a foundation for exploring the roles that these siderophores may play in human opportunistic infections.
KeywordsSiderophores Pantoea Desferrioxamine Aerobactin Enterobactin Horizontal transfer
This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada (2015–06417) and the Canada Foundation for Innovation (28591).
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
Data generated or analyzed during this study are included in this published article (and its supplementary information files). Gene clusters and MLSA loci have been deposited in Genbank under accession numbers MH015021-MH015174.
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