title: Salmonella enterica serovar Typhimurium growth is inhibited by the concomitant binding of Zn(II) and a pyrrolyl-hydroxamate to ZnuA, the soluble component of the ZnuABC transporter.
abstract: BACKGROUND
  Under conditions of Zn(II) deficiency, the most relevant high affinity Zn(II) transport system synthesized by many Gram-negative bacteria is the ZnuABC transporter. ZnuABC is absent in eukaryotes and plays an important role in bacterial virulence. Consequently, ZnuA, the periplasmic component of the transporter, appeared as a good target candidate to find new compounds able to contrast bacterial growth by interfering with Zn(II) uptake.
  
  
  METHODS
  Antibacterial activity assays on selected compounds from and in-house library against Salmonella enterica serovar Typhimurium ATCC14028 were performed. The X-ray structure of the complex formed by SeZnuA with an active compound was solved at 2.15Å resolution.
  
  
  RESULTS
  Two di-aryl pyrrole hydroxamic acids differing in the position of a chloride ion, RDS50 ([1-[(4-chlorophenyl)methyl]-4-phenyl-1H-pyrrol-3-hydroxamic acid]) and RDS51 (1-[(2-chlorophenyl)methyl]-4-phenyl-1H-pyrrol-3-hydroxamic acid) were able to inhibit Salmonella growth and its invasion ability of Caco-2 cells. The X-ray structure of SeZnuA containing RDS51 revealed its presence at the metal binding site concomitantly with Zn(II) which is coordinated by protein residues and the hydroxamate moiety of the compound.
  
  
  CONCLUSIONS
  Two molecules interfering with ZnuA-mediated Zn(II) transport in Salmonella have been identified for the first time. The resolution of the SeZnuA-RDS51 X-ray structure revealed that RDS51 is tightly bound both to the protein and to Zn(II) thereby inhibiting its release. These features pave the way to the rational design of new Zn(II)-binding drugs against Salmonella.
  
  
  CONCLUSIONS
  The data reported show that targeting the bacterial ZnuABC transporter can represent a good strategy to find new antibiotics against Gram-negative bacteria.
authors.affiliation: CNR-Institute of Molecular Biology and Pathology and Pasteur Institute Fondazione Cenci Bolognetti c/o Department of Biochemical Sciences, 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy. Electronic address: andrea.ilari@uniroma1.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Ilari
authors.affiliation: Department of Chemistry and Technology of Drugs, Pasteur Institute Fondazione Cenci Bolognetti, 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Pescatori
authors.affiliation: Department of Chemistry and Technology of Drugs, Pasteur Institute Fondazione Cenci Bolognetti, 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Di Santo
authors.affiliation: Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Battistoni
authors.affiliation: Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Ammendola
authors.affiliation: Department of Biology, University of Rome 'Tor Vergata', Via della Ricerca Scientifica 1, 00133 Rome, Italy.
authors.forename: Mattia
authors.initials: M
authors.lastname: Falconi
authors.affiliation: Department of Public Health and Infectious Diseases, 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Berlutti
authors.affiliation: Department of Public Health and Infectious Diseases, 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy.
authors.forename: Piera
authors.initials: P
authors.lastname: Valenti
authors.affiliation: Department of Biochemical Sciences 'Sapienza' University of Rome, Piazzale A. Moro, 5, 00185 Rome, Italy. Electronic address: emilia.chiancone@uniroma1.it.
authors.forename: Emilia
authors.initials: E
authors.lastname: Chiancone
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000378:metabolism*; D018938:Caco-2 Cells; D027682:Cation Transport Proteins / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000737:chemistry / Q000494:pharmacology*; D011758:Pyrroles / Q000737:chemistry / Q000494:pharmacology*; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D015032:Zinc / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D027682:Cation Transport Proteins; D006877:Hydroxamic Acids; D011758:Pyrroles; C464647:ZnuC protein, Salmonella enterica; D015032:Zinc
keywords: Lead compounds; Salmonella enterica; X-ray structure; ZnuA; ZnuABC zinc transporter