title: Heme interplay between IlsA and IsdC: Two structurally different surface proteins from Bacillus cereus.
abstract: BACKGROUND
  Iron is an essential element for bacterial growth and virulence. Because of its limited bioavailability in the host, bacteria have adapted several strategies to acquire iron during infection. In the human opportunistic bacteria Bacillus cereus, a surface protein IlsA is shown to be involved in iron acquisition from both ferritin and hemoproteins. IlsA has a modular structure consisting of a NEAT (Near Iron transporter) domain at the N-terminus, several LRR (Leucine Rich Repeat) motifs and a SLH (Surface Layer Homology) domain likely involved in anchoring the protein to the cell surface.
  
  
  METHODS
  Isothermal titration calorimetry, UV-Vis spectrophotometry, affinity chromatography and rapid kinetics stopped-flow measurements were employed to probe the binding and transfer of hemin between two different B. cereus surface proteins (IlsA and IsdC).
  
  
  RESULTS
  IlsA binds hemin via the NEAT domain and is able to extract heme from hemoglobin whereas the LRR domain alone is not involved in these processes. A rapid hemin transfer from hemin-containing IlsA (holo-IlsA) to hemin-free IsdC (apo-IsdC) is demonstrated.
  
  
  CONCLUSIONS
  For the first time, it is shown that two different B. cereus surface proteins (IlsA and IsdC) can interact and transfer heme suggesting their involvement in B. cereus heme acquisition.
  
  
  CONCLUSIONS
  An important role for the complete Isd system in heme-associated bacterial growth is demonstrated and new insights into the interplay between an Isd NEAT surface protein and an IlsA-NEAT-LRR protein, both of which appear to be involved in heme-iron acquisition in B. cereus are revealed.
authors.affiliation: INRA, UMR 1319 Micalis-AgroParisTech, AgroParisTech UMR Micalis, F-78352 Jouy en Josas, France; Laboratory of Biotechnology, Saint-Joseph University, Beyrouth, Lebanon; Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676, USA.
authors.forename: Elise
authors.initials: E
authors.lastname: Abi-Khalil
authors.affiliation: INRA, UMR 1319 Micalis-AgroParisTech, AgroParisTech UMR Micalis, F-78352 Jouy en Josas, France.
authors.forename: Diego
authors.initials: D
authors.lastname: Segond
authors.affiliation: Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676, USA.
authors.forename: Tyson
authors.initials: T
authors.lastname: Terpstra
authors.affiliation: INRA, MIG, Domaine de Vilvert, F-78352 Jouy en Josas, France.
authors.forename: Gwenaëlle
authors.initials: G
authors.lastname: André-Leroux
authors.affiliation: Laboratory of Biotechnology, Saint-Joseph University, Beyrouth, Lebanon.
authors.forename: Mireille
authors.initials: M
authors.lastname: Kallassy
authors.affiliation: INRA, UMR 1319 Micalis-AgroParisTech, AgroParisTech UMR Micalis, F-78352 Jouy en Josas, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Lereclus
authors.affiliation: Department of Chemistry, State University of New York at Potsdam, Potsdam, NY 13676, USA.
authors.forename: Fadi
authors.initials: F
authors.lastname: Bou-Abdallah
authors.affiliation: INRA, UMR 1319 Micalis-AgroParisTech, AgroParisTech UMR Micalis, F-78352 Jouy en Josas, France.
authors.forename: Christina
authors.initials: C
authors.lastname: Nielsen-Leroux
mesh_terms: D000595:Amino Acid Sequence; D001409:Bacillus cereus / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D006418:Heme / Q000737:chemistry* / Q000378:metabolism; D006427:Hemin / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D013816:Thermodynamics
chemical_list: D001426:Bacterial Proteins; D006418:Heme; D006427:Hemin; D007501:Iron
keywords: Hemin binding; Hemoglobin; IlsA NEAT domain; Kinetics; LRR domain