A key role for the periplasmic PfeE esterase in iron acquisition via the siderophore Enterobactin in Pseudomonas aeruginosa.
Fiche publication
Date publication
août 2018
Journal
ACS chemical biology
Auteurs
Membres identifiés du Cancéropôle Est :
Pr MELY Yves
Tous les auteurs :
Perraud Q, Moynie L, Gasser V, Munier M, Godet J, Hoegy F, Mély Y, Mislin GLA, Naismith JH, Schalk IJ
Lien Pubmed
Résumé
Enterobactin (ENT) is a siderophore (iron-chelating compound) produced by Escherichia coli in order to gain access to iron, an essential nutriment for bacterial growth. ENT is used as an exosiderophore by the opportunistic human pathogen Pseudomonas aeruginosa with transport of ferri-ENT across the bacterial outer membrane by the transporter PfeA. Next to pfeA gene on the chromosome is localized a gene encoding for an esterase, PfeE, whose transcription is regulated, as for pfeA, by the presence of ENT in bacterial environment. Purified PfeE hydrolyzed ferri-ENT into three molecules of 2,3 DHBS (2,3 dihydroxybenzoylserine) still complexed with ferric iron, and complete dissociation of iron from ENT chelating groups was only possible in the presence of both PfeE and an iron reducer, such as DTT. The crystal structure of PfeE and an inactive PfeE mutant complexed with ferri-ENT or a non-hydrolysable ferri-catechol complex allowed identification of the enzyme binding site and the catalytic triad. Finally, cell fractionation and fluorescence microscopy showed periplasmic localization of PfeE in P. aeruginosa cells. Thus, the molecular mechanism of iron release from ENT in P. aeruginosa differs from that previously described in E. coli. In P. aeruginosa, siderophore hydrolysis occurs in the periplasm, with ENT never reaching the bacterial cytoplasm. In E. coli, ferri-ENT crosses the inner membrane via the ABC transporter FepBCD and ferri-ENT is hydrolyzed by the esterase Fes only once it is in the cytoplasm.
Mots clés
Bacterial Proteins, chemistry, Binding Sites, Crystallography, X-Ray, Enterobactin, metabolism, Esterases, chemistry, Humans, Hydrolysis, Iron, metabolism, Models, Molecular, Protein Conformation, Pseudomonas Infections, microbiology, Pseudomonas aeruginosa, chemistry, Siderophores, metabolism
Référence
ACS Chem. Biol.. 2018 Aug 7;: