Cellular organization of siderophore biosynthesis in Pseudomonas aeruginosa: Evidence for siderosomes

• Siderophore biosynthesis pathways are complex and involve different enzymes.
• These biosynthesis pathways have a specific cellular organization in siderosomes.

Pyoverdine I (PVDI) and pyochelin (PCH) are the two major siderophores produced by Pseudomonas aeruginosa PAO1 to import iron. The biochemistry of the biosynthesis of these two siderophores has been described in detail in the literature over recent years. PVDI assembly requires the coordinated action of seven cytoplasmic enzymes and is followed by a periplasmic maturation before secretion of the siderophore into the extracellular medium by the efflux system PvdRT-OpmQ. PCH biosynthesis also involves seven cytoplasmic enzymes but no periplasmic maturation. Recent findings indicate that the cytoplasmic enzymes involved in each of these two siderophore biosynthesis pathways can form siderophore-specific multi-enzymatic complexes called siderosomes associated with the inner leaflet of the cytoplasmic membrane. This organization may optimize the transfer of the siderophore precursors between the various participating enzymes and avoid the diffusion of siderophore precursors, able to chelate metals, throughout the cytoplasm. Here, we describe these recently published findings and discuss the existence of these siderosomes in P. aeruginosa.

This review focuses on recent findings indicating that siderophore biosynthesis pathways in bacteria have a high cellular organization. The enzymes involved in such processes can form siderophore-specific multi-enzymatic complexes called siderosomes associated with the inner leaflet of the cytoplasmic membrane. This cellular organization probably ensures the efficiency of siderophore biosynthesis.Figure optionsDownload as PowerPoint slide