The <i>E. coli</i> Siderophores Enterobactin and Salmochelin Form Six‐Coordinate Silicon Complexes at Physiological pH

Schmiederer, Timo; Rausch, Saskia; Valdebenito, Marianne; Mantri, Yogita; Mösker, Eva; Baramov, Todor; Stelmaszyk, Kamil; Schmieder, Peter; Butz, Diane; Müller, Silke I.; Schneider, Kathrin; Baik, Mu‐Hyun; Hantke, Klaus; Süssmuth, Roderich D.

doi:10.1002/anie.201005792

Cited by 24 publications

(17 citation statements)

References 30 publications

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“…Moreover, crystal structures of enterobactin complexes of V(IV), Si(IV), Ge(IV), and Ti(IV) show that these complexes all assume a Δ configuration. 27,29,30,49 The present crystal structure affords a definitive Δ assignment to [Fe(ent)] 3− , which is readily distinguished from [Fe(D-ent)] 3− by the stereochemistry at the serine units (Figure 2C). The relationship between the CD spectra of [Fe(ent)] 3− and [Fe(D-ent)] 3− indicates that the handedness of the latter is opposite at the metal center.…”

Section: Resultsmentioning

confidence: 66%

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Determination of the Molecular Structures of Ferric Enterobactin and Ferric Enantioenterobactin Using Racemic Crystallography

Johnstone

Nolan

2017

J. Am. Chem. Soc.

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Enterobactin is a secondary metabolite produced by Enterobacteriaceae for acquiring iron, an essential metal nutrient. The biosynthesis and utilization of enterobactin permits many Gram-negative bacteria to thrive in environments where low soluble iron concentrations would otherwise preclude survival. Despite extensive work carried out on this celebrated molecule since its discovery over 40 years ago, the ferric enterobactin complex has eluded crystallographic structural characterization. We report the successful growth of single crystals containing ferric enterobactin using racemic crystallization, a method that involves cocrystallization of a chiral molecule with its mirror image. The structures of ferric enterobactin and ferric enantioenterobactin obtained in this work provide a definitive assignment of the stereochemistry at the metal center and reveal secondary coordination sphere interactions. The structures were employed in computational investigations of the interactions of these complexes with two enterobactin-binding proteins, which illuminate the influence of metal-centered chirality on these interactions. This work highlights the utility of small-molecule racemic crystallography for obtaining elusive structures of coordination complexes.

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Section: Resultsmentioning

confidence: 66%

“…This macrolactone conformation has also been observed in crystal structures of (i) the parent serine trilactone and (ii) enterobactin complexes of Si(IV), Ti(IV), Ge(IV), and V(IV). 29,30,56 …”

Section: Resultsmentioning

confidence: 99%

Determination of the Molecular Structures of Ferric Enterobactin and Ferric Enantioenterobactin Using Racemic Crystallography

Johnstone

Nolan

2017

J. Am. Chem. Soc.

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“…105 This work was motivated by the observation that enterobactin and salmochelin S4 bind silicon. 106 …”

Section: Fuelling Nitrogenase: Molybdenum and Vanadiummentioning

confidence: 99%

Beyond iron: non-classical biological functions of bacterial siderophores

2015

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Bacteria secrete small molecules known as siderophores to acquire iron from their surroundings. For over 60 years, investigations into the bioinorganic chemistry of these molecules, including fundamental coordination chemistry studies, have provided insight into the crucial role that siderophores play in bacterial iron homeostasis. The importance of understanding the fundamental chemistry underlying bacterial life has been highlighted evermore in recent years because of the emergence of antibiotic-resistant bacteria and the need to prevent the global rise of these superbugs. Increasing reports of siderophores functioning in capacities other than iron transport have appeared recently, but reports of “non-classical” siderophore functions have long paralleled those of iron transport. One particular non-classical function of these iron chelators, namely antibiotic activity, was even documented before the role of siderophores in iron transport was established. In this Perspective, we present an exposition of past and current work into non-classical functions of siderophores and highlight the directions in which we anticipate that this research is headed. Examples include the ability of siderophores to function as zincophores, chalkophores, and metallophores for a variety of other metals, sequester heavy metal toxins, transport boron, act as signalling molecules, regulate oxidative stress, and provide antibacterial activity.

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“…Yoshikawa later reported the resolution of these cations into their configurationally stable Λ and Δ enantiomers . The hydrolytic stability of some hexacoordinate silicon complexes was also corroborated by Klüfers, who investigated hydrogen‐bonded sugar‐alcohol trimers as hexadentate silicon chelators in aqueous solution, and by Süssmuth, who developed hydrolytically stable enterobactin silicon(IV) complexes based on tris(catecholato) coordination. Finally, Kotali and co‐workers recently synthesized neutral hexacoordinate bis‐tridentate silicon(IV) complexes and found them to be hydrolytically stable in a water/DMSO mixture .…”

Section: Introductionmentioning

confidence: 82%

Progress in the Synthesis and Bioactivity of Hexacoordinate Silicon(IV) Complexes

et al. 2016

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(Arenediolato)bis(polypyridyl)silicon(IV) complexes contain hexacoordinate silicon and are surprisingly stable against hydrolysis in water. In an ongoing research program, we are aiming to exploit them as new structural templates for the design of bioactive compounds. As a follow‐up to previous work, here we present our progress in the synthesis of hexacoordinate silicon complexes by selective ortho‐double nitration of the electron‐rich catecholato ligand, followed by reduction to diamines and condensation either with 1,2‐diketones or with aldehydes. Binding epitopes of some representative complexes to G‐quadruplex DNA as determined by NMR spectroscopic titration are presented.

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The E. coli Siderophores Enterobactin and Salmochelin Form Six‐Coordinate Silicon Complexes at Physiological pH

Cited by 24 publications

References 30 publications

Determination of the Molecular Structures of Ferric Enterobactin and Ferric Enantioenterobactin Using Racemic Crystallography

Determination of the Molecular Structures of Ferric Enterobactin and Ferric Enantioenterobactin Using Racemic Crystallography

Beyond iron: non-classical biological functions of bacterial siderophores

Progress in the Synthesis and Bioactivity of Hexacoordinate Silicon(IV) Complexes

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