title: Structural Biology of Bacterial Haemophores.
abstract: Iron plays a key role in a wide range of metabolic and signalling functions representing an essential nutrient for almost all forms of life. However, the ferric form is hardly soluble, whereas the ferrous form is highly toxic. Thus, in biological fluids, most of the iron is sequestered in iron- or haem-binding proteins and the level of free iron is low, making haem and iron acquisition a challenge for pathogenic bacteria during infections. Although toxic to the host, free haem is a major and readily available source of iron for several pathogenic microorganisms. Both Gram-positive and Gram-negative bacteria have developed several strategies to acquire free haem-Fe and protein-bound haem-Fe. Haemophores are a class of secreted and cell surface-exposed proteins promoting free-haem uptake, haem extraction from host haem proteins, and haem presentation to specific outer-membrane receptors that internalize the metal-porphyrins. Here, structural biology of bacterial haemophores is reviewed focusing on haem acquisition, haem internalization, and haem-degrading systems.
authors.affiliation: Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, Roma, Italy; Istituto di Bioscienze e BioRisorse, Consiglio Nazionale delle Ricerche, Napoli, Italy. Electronic address: ascenzi@uniroma3.it.
authors.forename: Paolo
authors.initials: P
authors.lastname: Ascenzi
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Roma, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: di Masi
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Roma, Italy.
authors.forename: Loris
authors.initials: L
authors.lastname: Leboffe
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Roma, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Frangipani
authors.affiliation: Dipartimento di Bioscienze, Università di Milano, Milano, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Nardini
authors.affiliation: Istituto di Bioscienze e BioRisorse, Consiglio Nazionale delle Ricerche, Napoli, Italy; Dipartimento di Scienze, Università Roma Tre, Roma, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Verde
authors.affiliation: Dipartimento di Scienze, Università Roma Tre, Roma, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Visca
mesh_terms: D001419:Bacteria / Q000201:enzymology* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D008958:Models, Molecular; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D006418:Heme; D007501:Iron
keywords: Bacterial haemophores; Haem acquisition; Haem degradation; Haem internalization; Structure–function relationships