title: Surface interactome in Streptococcus pyogenes.
abstract: Very few studies have so far been dedicated to the systematic analysis of protein interactions occurring between surface and/or secreted proteins in bacteria. Such interactions are expected to play pivotal biological roles that deserve investigation. Taking advantage of the availability of a detailed map of surface and secreted proteins in Streptococcus pyogenes (group A Streptococcus (GAS)), we used protein array technology to define the "surface interactome" in this important human pathogen. Eighty-three proteins were spotted on glass slides in high density format, and each of the spotted proteins was probed for its capacity to interact with any of the immobilized proteins. A total of 146 interactions were identified, 25 of which classified as "reciprocal," namely, interactions that occur irrespective of which of the two partners was immobilized on the chip or in solution. Several of these interactions were validated by surface plasmon resonance and supported by confocal microscopy analysis of whole bacterial cells. By this approach, a number of interesting interactions have been discovered, including those occurring between OppA, DppA, PrsA, and TlpA, proteins known to be involved in protein folding and transport. These proteins, all localizing at the septum, might be part, together with HtrA, of the recently described ExPortal complex of GAS. Furthermore, SpeI was found to strongly interact with the metal transporters AdcA and Lmb. Because SpeI strictly requires zinc to exert its function, this finding provides evidence on how this superantigen, a major player in GAS pathogenesis, can acquire the metal in the host environment, where it is largely sequestered by carrier proteins. We believe that the approach proposed herein can lead to a deeper knowledge of the mechanisms underlying bacterial invasion, colonization, and pathogenesis.
authors.affiliation: Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy.
authors.forename: Cesira L
authors.initials: CL
authors.lastname: Galeotti
authors.forename: Elia
authors.initials: E
authors.lastname: Bove
authors.forename: Alfredo
authors.initials: A
authors.lastname: Pezzicoli
authors.forename: Renzo
authors.initials: R
authors.lastname: Nogarotto
authors.forename: Nathalie
authors.initials: N
authors.lastname: Norais
authors.forename: Silvia
authors.initials: S
authors.lastname: Pileri
authors.forename: Barbara
authors.initials: B
authors.lastname: Lelli
authors.forename: Fabiana
authors.initials: F
authors.lastname: Falugi
authors.forename: Sergio
authors.initials: S
authors.lastname: Balloni
authors.forename: Vittorio
authors.initials: V
authors.lastname: Tedde
authors.forename: Emiliano
authors.initials: E
authors.lastname: Chiarot
authors.forename: Mauro
authors.initials: M
authors.lastname: Bombaci
authors.forename: Marco
authors.initials: M
authors.lastname: Soriani
authors.forename: Luisa
authors.initials: L
authors.lastname: Bracci
authors.forename: Guido
authors.initials: G
authors.lastname: Grandi
authors.forename: Renata
authors.initials: R
authors.lastname: Grifantini
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002712:Chlorides / Q000494:pharmacology; D040081:Protein Array Analysis; D011485:Protein Binding / Q000187:drug effects; D013297:Streptococcus pyogenes / Q000378:metabolism*; D017967:Zinc Compounds / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D002712:Chlorides; D017967:Zinc Compounds; C016837:zinc chloride