albomycins

Albomycins are a family of antibiotic compounds known as sideromycins, produced by certain Streptomyces species. They are composed of a ferrichrome-type siderophore moiety covalently linked to a nucleoside-like antibiotic component. This dual structure enables the molecules to hijack bacterial iron uptake systems to gain entry into the cell, a “Trojan horse” mode of action.

The siderophore portion chelates ferric iron (Fe3+) and is recognized by bacterial siderophore receptors, facilitating transport across the outer membrane and into the periplasm or cytoplasm. Once inside, the antibiotic fragment is released, and the active moiety inhibits essential steps in protein synthesis. In albomycins, the antibiotic component targets aminoacyl-tRNA synthetases, notably seryl-tRNA synthetase, thereby blocking protein synthesis and inhibiting bacterial growth.

Several congeners have been identified, such as albomycin δ2 and related variants. While all share the same general architecture of a siderophore linked to a nucleoside-like antibiotic, differences in the siderophore or antibiotic portions influence uptake and activity.

Biological activity of albomycins is influenced by iron availability and the expression of bacterial siderophore transport systems. They show in vitro activity against a range of bacteria, with uptake mediated by iron-scavenging pathways. Despite significant research interest, albomycins have not become clinically approved drugs; they remain primarily of interest as models for siderophore–antibiotic conjugates and for studying mechanisms of siderophore-mediated drug delivery and potential derivatives.