[9] Due to their bridging the gaps between pathogenicity, iron metabolism, and fluorescence, pyoverdines have piqued the curiosity of scientists around the world for over 100 years.

[citation needed] Like most siderophores, pyoverdine is synthesized and secreted into the environment when the microorganism that produces it detects that intracellular iron concentrations have fallen below a preset threshold.

Unlike fluorescence, spectroscopic absorption shows little quenching upon iron-binding, suggesting that the mechanism for molecular relaxation is vibrational, rather than via electromagnetic radiation.

This results in a very tightly coordinated octahedral complex that efficiently prevents the ingress of water or other materials that may disrupt binding.

Pyoverdine is structurally similar to azobactin, from Azotobacter vinelandii, except that the latter possesses an extra urea ring.

For reasons that remain unclear, pyoverdine biosynthesis is strongly inhibited by the anti-cancer therapeutic fluorouracil,[15] particularly through its ability to disrupt RNA metabolism.

Originally, it was widely thought to be synthesized by the pvcABCD operon, as deletion of portions of the pvcC and pvcD genes disrupts pyoverdine production.

A separate report suggests that pvcABCD may be responsible for the synthesis of paerucumarin (a pseudoverdine-related molecule) instead, and claims that loss of activity in the locus has no effect on pyoverdine production.

Several of the genes responsible for pyoverdine biosynthesis (e.g., pvdH, pvdA, and pvdF) are involved in the generation of precursor and alternate amino acids necessary for various portions of the molecule.

[6][15][25][26] As noted above, pyoverdine contributes in several fashions to general virulence, including regulating the production of itself, exotoxin A (which stalls translation), and the protease PrpL.

In 2001, Albesa and colleagues reported that pyoverdine purified from a strain of P. fluorescens exhibited profound cytotoxicity to mammalian macrophages and that this effect was at least partially dependent upon reactive oxygen species.

[27] Later, Kirienko and colleagues determined that pyoverdine is both necessary and sufficient for killing C. elegans, that enters host cells, destabilizes mitochondrial dynamics, and induces a hypoxic response.

[6][7] Exposure triggers a response that is consistent with hypoxia that depends on the HIF-1 protein, suggesting that the host perceives a condition where it lacks the molecular tools for generating ATP (generally, iron, oxygen, and cellular reducing equivalents).

[33][34] In P. aeruginosa, pyoverdine non-producing “cheat” bacteria have been shown to i) evolve readily from a producing ancestor;[35] and ii) outcompete cooperating strains in mixed culture in a density- and frequency-dependent manner.

The competitive advantage of pyoverdine non-producers over producers in mixed culture was shown to be maximized when environments are well-mixed and molecules diffuse readily (low spatial structure) and when the costs and benefits of pyoverdine production are high, i.e. when iron is strongly limited.

[42] Pseudoverdine is relatively similar to pyoverdine in its fluorescence and other spectroscopic properties, and its ability to chelate ferric iron, albeit at much lower affinity.