title: Enlightening mineral iron sensing in Pseudomonas fluorescens by surface active maghemite nanoparticles: Involvement of the OprF porin.
abstract: Mineral iron(III) recognition by bacteria is considered a matter of debate. The peculiar surface chemistry of novel naked magnetic nanoparticles, called SAMNs (surface active maghemite nanoparticles) characterized by solvent exposed Fe(3+) sites on their surface, was exploited for studying mineral iron sensing in Pseudomonas fluorescens.
  
  
  
  SAMNs were applied for mimicking Fe(3+) ions in solution, acting as magnetically drivable probes to evaluate putative Fe(3+) recognition sites on the microorganism surface. Culture broths and nano-bio-conjugates were characterized by UV-Vis spectroscopy and mass spectrometry.
  
  
  
  The whole heritage of a membrane porin (OprF) of P. fluorescens Ps_22 cells was recognized and firmly bound by SAMNs. The binding of nanoparticles to OprF porin was correlated to a drastic inhibition of a siderophore (pyoverdine) biosynthesis and to the stimulation of the production and rate of formation of a secondary siderophore. The analysis of metabolic pathways, based on P. fluorescens Ps_22 genomic information, evidenced that this putative secondary siderophore does not belong to a selection of the most common siderophores.
  
  
  
  In the scenario of an adhesion mechanism, it is plausible to consider OprF as the biological component deputed to the mineral iron sensing in P. fluorescens Ps_22, as well as one key of siderophore regulation.
  
  
  
  The present work sheds light on mineral iron sensing in microorganisms. Peculiar colloidal naked iron oxide nanoparticles offer a useful approach for probing the adhesion of bacterial surface on mineral iron for the identification of the specific recognition site for this iron uptake regulation in microorganisms.
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy; Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Palacky University in Olomouc, Czech Republic. Electronic address: massimiliano.magro@unipd.it.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Magro
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: luca.fasolato@unipd.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Fasolato
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: emanuela.bonaiuto@unidp.it.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Bonaiuto
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: nadiaandrea.andreani@studenti.unipd.it.
authors.forename: Nadia Andrea
authors.initials: NA
authors.lastname: Andreani
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: davide.baratella@studenti.unipd.it.
authors.forename: Davide
authors.initials: D
authors.lastname: Baratella
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: vittorino.corraducci@unipd.it.
authors.forename: Vittorino
authors.initials: V
authors.lastname: Corraducci
authors.affiliation: Department of Molecular Medicine, University of Padova, Italy. Electronic address: gianni.miotto@unipd.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Miotto
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy. Electronic address: barbara.cardazzo@unipd.it.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cardazzo
authors.affiliation: Department of Comparative Biomedicine and Food Science, University of Padova, Italy; Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Palacky University in Olomouc, Czech Republic. Electronic address: fabio.vianello@unipd.it.
authors.forename: Fabio
authors.initials: F
authors.lastname: Vianello
mesh_terms: D001422:Bacterial Adhesion / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005290:Ferric Compounds / Q000737:chemistry; D007501:Iron / Q000737:chemistry; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry / Q000378:metabolism; D018272:Porins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000737:chemistry / Q000378:metabolism; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D001425:Bacterial Outer Membrane Proteins; D005290:Ferric Compounds; D058185:Magnetite Nanoparticles; D008903:Minerals; D018272:Porins; D013501:Surface-Active Agents; C000499:ferric oxide; D007501:Iron
keywords: Bacteria; Iron sensing; Maghemite nanoparticles; Membrane proteins; Oprf porin; Siderophores