title: The Human Pathogen Streptococcus pyogenes Releases Lipoproteins as Lipoprotein-rich Membrane Vesicles.
abstract: Bacterial lipoproteins are attractive vaccine candidates because they represent a major class of cell surface-exposed proteins in many bacteria and are considered as potential pathogen-associated molecular patterns sensed by Toll-like receptors with built-in adjuvanticity. Although Gram-negative lipoproteins have been extensively characterized, little is known about Gram-positive lipoproteins. We isolated from Streptococcus pyogenes a large amount of lipoproteins organized in vesicles. These vesicles were obtained by weakening the bacterial cell wall with a sublethal concentration of penicillin. Lipid and proteomic analysis of the vesicles revealed that they were enriched in phosphatidylglycerol and almost exclusively composed of lipoproteins. In association with lipoproteins, a few hypothetical proteins, penicillin-binding proteins, and several members of the ExPortal, a membrane microdomain responsible for the maturation of secreted proteins, were identified. The typical lipidic moiety was apparently not necessary for lipoprotein insertion in the vesicle bilayer because they were also recovered from the isogenic diacylglyceryl transferase deletion mutant. The vesicles were not able to activate specific Toll-like receptor 2, indicating that lipoproteins organized in these vesicular structures do not act as pathogen-associated molecular patterns. In light of these findings, we propose to name these new structures Lipoprotein-rich Membrane Vesicles.
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Biagini
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Manuela
authors.initials: M
authors.lastname: Garibaldi
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Susanna
authors.initials: S
authors.lastname: Aprea
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Alfredo
authors.initials: A
authors.lastname: Pezzicoli
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Francesco
authors.initials: F
authors.lastname: Doro
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Marco
authors.initials: M
authors.lastname: Becherelli
authors.affiliation: §Centro Interdipartimentale di Microscopia Elettronica, Università della Tuscia, Viterbo, Italy;
authors.forename: Anna Rita
authors.initials: AR
authors.lastname: Taddei
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Chiara
authors.initials: C
authors.lastname: Tani
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Simona
authors.initials: S
authors.lastname: Tavarini
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Marirosa
authors.initials: M
authors.lastname: Mora
authors.affiliation: ¶Dipartimento di Scienze Pediatriche, Ginecologiche, Microbiologiche e Biomediche, Università degli Studi di Messina, Messina, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Teti
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Ugo
authors.initials: U
authors.lastname: D'Oro
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Sandra
authors.initials: S
authors.lastname: Nuti
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Marco
authors.initials: M
authors.lastname: Soriani
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Immaculada
authors.initials: I
authors.lastname: Margarit
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Rino
authors.initials: R
authors.lastname: Rappuoli
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay;
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.affiliation: From the ‡Novartis Vaccines and Diagnostics (a GSK company), Via Fiorentiina 1, 53100 Siena, Itlay; nathalie.x.norais@gsk.com.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Norais
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D003470:Culture Media; D057809:HEK293 Cells; D006801:Humans; D008074:Lipoproteins / Q000378:metabolism*; D021962:Membrane Microdomains / Q000187:drug effects / Q000378:metabolism*; D008970:Molecular Weight; D009154:Mutation / Q000235:genetics; D010406:Penicillins / Q000494:pharmacology; D012984:Software; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000378:metabolism*; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D008074:Lipoproteins; D010406:Penicillins; D051195:Toll-Like Receptor 2