A novel Alteromonas phage with tail fiber containing six potential iron-binding domains

Abstract

Iron (Fe), as an essential micronutrient, is often a limiting factor for microbial growth in marine ecosystems. The Trojan Horse hypothesis suggests that iron in the phage tail fibers is recognized by the host’s siderophore-bound iron receptor, enabling the phage to attach and initiate infection. The potential role of phages as iron-binding ligands has significant implications for oceanic trace metal biogeochemistry. In this study, we isolated a new phage R22Y with the potential to bind iron ions, using Alteromonas , a major siderophore producer, as the host. The tail fiber structure of R22Y exhibits six conserved HxH motifs, suggesting that each phage could potentially bind up to 36 iron ions. R22Y may contribute to colloidal organically complexed dissolved iron in the marine environment. This finding provides further insights into the Trojan Horse hypothesis, suggesting that alterophages may act as natural iron-binding ligands in the marine environment.