An overview of siderophore biosynthesis among fluorescent Pseudomonads and new insights into their complex cellular organization

Abstract

Summary Siderophores are iron‐chelating molecules produced by bacteria to access iron, a key nutrient. These compounds have highly diverse chemical structures, with various chelating groups. They are released by bacteria into their environment to scavenge iron and bring it back into the cells. The biosynthesis of siderophores requires complex enzymatic processes and expression of the enzymes involved is very finely regulated by iron availability and diverse transcriptional regulators. Recent data have also highlighted the organization of the enzymes involved in siderophore biosynthesis into siderosomes, multi‐enzymatic complexes involved in siderophore synthesis. An understanding of siderophore biosynthesis is of great importance, as these compounds have many potential biotechnological applications because of their metal‐chelating properties and their key role in bacterial growth and virulence. This review focuses on the biosynthesis of siderophores produced by fluorescent Pseudomonads, bacteria capable of colonizing a large variety of ecological niches. They are characterized by the production of chromopeptide siderophores, called pyoverdines, which give the typical green colour characteristic of fluorescent pseudomonad cultures. Secondary siderophores are also produced by these strains and can have highly diverse structures (such as pyochelins, pseudomonine, yersiniabactin, corrugatin, achromobactin and quinolobactin).

Increasing the copper sensitivity of microorganisms by restricting iron supply, a strategy for bio‐management practices

“…Thus, because the activity of the metal detoxification pumps can hide metal toxicity effects, mutants that lack the efflux pumps are suitable to test elevated metal stress and its consequences on iron homoeostasis. In P. aeruginosa , excess Cu + , Zn 2+ , Co 2+ , Ni 2+ or Cd 2+ affects siderophore synthesis (Visca et al , 1992; Teitzel et al , 2006; Schalk et al , 2020). It was shown that genes encoding synthesis of pyoverdine were upregulated in response to Cu + , Zn 2+ and Cd 2+ suggesting that pyoverdine may protect the cells by sequestering heavy metals.…”

“…It was shown that genes encoding synthesis of pyoverdine were upregulated in response to Cu + , Zn 2+ and Cd 2+ suggesting that pyoverdine may protect the cells by sequestering heavy metals. Nevertheless, although able to chelate Cu + , Zn 2+ and Cd 2+ , pyoverdine is highly iron specific and its affinity to iron is much more higher, indicating that it might rather provide the bacterium with iron under excess metal (Visca et al , 1992; Teitzel et al , 2006; Schalk et al , 2020). In contrast, pyochelin has a broader specificity for cations and its synthesis was repressed by Cu + , Cd 2+ , Co 2+ and Ni 2+ .…”

From heterogeneity to homogeneity: coordination of siderophore gene expression among clonal cells of the bacterium Pseudomonas aeruginosa

“…Due to their extra-cellular mode of action and their high diffusivity, siderophores can be considered 'public goods', benefiting other cells in a clonal group [5]. P. aeruginosa produces two siderophores, pyochelin and pyoverdine via non-ribosomal peptide synthesis [22]. The regulation of these two siderophores involves three levels.…”

“…P. aeruginosa produces two siderophores, pyochelin and pyoverdine via non-ribosomal peptide synthesis [22]. The regulation of these two siderophores involves three levels.…”

Ecology drives the evolution of diverse siderophore-production strategies in the opportunistic human pathogen Pseudomonas aeruginosa

“…Iron-loaded pyoverdine is imported by bacteria via a specific receptor. Import is followed by iron reduction, release from the siderophore, and subsequent recycling of pyoverdine (Kramer et al 2020; Schalk et al 2020). Pyoverdine production is a cooperative trait, because the molecules are costly for the individual cell to produce, but once loaded with iron they become available to other cells in the local neighbourhood (Buckling et al 2007; Harrison, 2013).…”