The biosynthesis of pyoverdines

Abstract

Pyoverdines are fluorescent siderophores of pseudomonads that play important roles for growth under iron-limiting conditions. The production of pyoverdines by fluorescent pseudomonads permits their colonization of hosts ranging from humans to plants. Prominent examples include pathogenic or non-pathogenic species such as Pseudomonas aeruginosa, P. putida, P. syringae, or P. fluorescens. Many distinct pyoverdines have been identified, all of which have a dihydroxyquinoline fluorophore in common, derived from oxidative cyclizations of non-ribosomal peptides. These serve as precursor of pyoverdines and are commonly known as ferribactins. Ferribactins of distinct species or even strains often differ in their sequence, resulting in a large variety of pyoverdines. However, synthesis of all ferribactins begins with an L-Glu/D-Tyr/L-Dab sequence, and the fluorophore is generated from the D-Tyr/L-Dab residues. In addition, the initial L-Glu residue is modified to various acids and amides that are responsible for the range of distinguishable pyoverdines in individual strains. While ferribactin synthesis is a cytoplasmic process, the maturation to the fluorescent pyoverdine as well as the tailoring of the initial glutamate are exclusively periplasmic processes that have been a mystery until recently. Here we review the current knowledge of pyoverdine biosynthesis with a focus on the recent advancements regarding the periplasmic maturation and tailoring reactions.

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

“…Ringel et al . showed by mass spectrometry that the only pyoverdine produced by a pvdN mutant is the α‐ketoglutarate form, indicating that transformation to the succinamide derivatives does not occur and must be carried out by PvdN (Ringel et al ., ; Ringel and Brüser, ). PtaA (PflA506_4424) is also a pyridoxal phosphate‐dependent transaminase and requires cytoplasmic cofactor assembly for folding and transport to the periplasm (Ringel et al ., ).…”

“…Some Pseudomonas strains carry both ptaA and pvdN in their genome, leading to strains that are able to produce different variants of pyoverdine. On the other hand, some Pseudomonas strains have only pvdN or ptaA and consequently only produce the corresponding variant (α‐ketoglutaric acid or succinamide derivative variants) (Ringel and Brüser, ). PtaA can act on several different substrates, i.e.…”

“…Pseudomonas aeruginosa is the archetype among fluorescent Pseudomonads and most of the data found in the literature and presented here will concern this pathogen; however, parallels will be made with siderophore biosynthesis among other fluorescent Pseudomonads, when possible. Pseudomonas aeruginosa strains produce four distinct pyoverdines, called PVDI, PVDII, PVDIII and PVDIV, and PCH as a secondary siderophore (Schalk and Guillon, ; Gasser et al ., ; Ringel and Brüser, ; Ronnebaum and Lamb, ). Many detailed reviews have already been published on PVDI and PCH biosynthesis (Visca et al ., ; Schalk and Guillon, ; Gasser et al ., ; Ringel and Brüser, ; Ronnebaum and Lamb, ).…”

“…Pseudomonas aeruginosa strains produce four distinct pyoverdines, called PVDI, PVDII, PVDIII and PVDIV, and PCH as a secondary siderophore (Schalk and Guillon, ; Gasser et al ., ; Ringel and Brüser, ; Ronnebaum and Lamb, ). Many detailed reviews have already been published on PVDI and PCH biosynthesis (Visca et al ., ; Schalk and Guillon, ; Gasser et al ., ; Ringel and Brüser, ; Ronnebaum and Lamb, ). Thus, we will provide a general description of their biosynthesis and highlight recent and original data concerning the cellular organization of the siderophore biosynthetic machinery.…”

Cooperation in Microbial Populations: Theory and Experimental Model Systems

“…Prominent examples of cooperating microbes are siderophore-producing pseudomonads, with the best known group of siderophores being the fluorescent 34 peptidic pyoverdines [37,52,42,296]. Pyoverdines serve as iron-scavenging pigments and thereby enable cells to uptake iron, an essential element for almost every living organism, including pseudomonads [42].…”