Iron uptake and molecular recognition in Pseudomonas putida: receptor mapping with ferrioxamine B, coprogen B and their biomimetic analogues

Abstract

This study shows that Pseudomonas putida possesses active uptake systems for Fe3+-ferrioxamine B (FOB) and Fe3+-coprogen B (Cop. B). These systems were characterized using natural and synthetic siderophores as structural probes. The synthetic analogues p178, p191, p239, p254 and p271 are a family of systematically modified linear retro-trishydroxamates that have shorter links between the ion binding groups relative to the natural compounds and possess chiral centres. They form a lower number of isomeric Fe3+ complexes relative to the natural compounds, and may be regarded as their specific conformers. Growth promotion and facilitated 55Fe3+ uptake using both natural and synthetic siderophores were studied. The results obtained, along with those from competition experiments between the natural and the synthetic analogues demonstrate that: (i) the FOB and Cop. B uptake systems share common transport determinants; (ii) FOB and Cop. B make use of separate receptors; (iii) the Cop. B receptor is conformationally more demanding than the FOB receptor; and (iv) the FOB receptor has preference for the &cis configuration although the natural siderophore is achiral. These results also demonstrate the usefulness of the synthetic analogues as structural probes. Some of these analogues simulate the natural counterparts as Fe3+ carriers, while others merely inhibit the action of the natural compounds by competing for the respective siderophore receptor.

Advances in the Chemical Biology of Desferrioxamine B

“…The uptake of specific enantiomeric forms of metal-siderophore complexes has been reported in Mycelia sterilia and in Pseudomonas aeruginosa and P. fluorescens . Other studies have informed understanding of siderophore-mediated Fe­(III) uptake using synthetic retro -analogues of DFOB containing hydroxamic acid groups in a reverse orientation to the natural molecule. − …”

Rare Earth Element (REE)-Dependent Growth of Pseudomonas putida KT2440 Relies on the ABC-Transporter PedA1A2BC and Is Influenced by Iron Availability

“…The same hypothesis might similarly explain why under high La 3+ concentrations and in the absence of Fe 2+/3+ supplementation, a pyoverdine-deficient strain is strongly impaired in growth. In this scenario the Fe 2+/3+ binding sites of pyoverdine-independent Fe transporters, such as the ferrichrome, ferrioxamine and ferric citrate uptake systems, might be occupied by La 3+ and prevent binding of Fe 2+/3+ ions (Jurkevitch et al, 1992; Cornelis, 2010). Consequently, a pyoverdine deficient strain would be unable to take up enough of this essential element that is, most likely, present at trace levels in the medium even without additional supplementation.…”

Rare earth element (REE)-dependent growth of Pseudomonas putida KT2440 depends on the ABC-transporter PedA1A2BC and is influenced by iron availability

“…The same hypothesis might similarly explain why under high La 3+ concentrations in the absence of Fe 3+ supplementation, a pyoverdine-deficient strain is strongly impaired in growth. In this scenario the Fe 2+/3+ binding sites of pyoverdine-independent Fe transporters, such as the ferrichrome, ferrioxamine and ferric citrate uptake systems, might be occupied by La 3+ and prevent binding of Fe 2+/3+ ions (Cornelis, 2010; Jurkevitch et al, 1992). Consequently, a pyoverdine deficient strain would be unable to take up enough of this essential element that is, most likely, present at trace levels in the medium even without additional supplementation.…”