title: Proteomics of protein secretion by Aggregatibacter actinomycetemcomitans.
abstract: The extracellular proteome (secretome) of periodontitis-associated bacteria may constitute a major link between periodontitis and systemic diseases. To obtain an overview of the virulence potential of Aggregatibacter actinomycetemcomitans, an oral and systemic human pathogen implicated in aggressive periodontitis, we used a combined LC-MS/MS and bioinformatics approach to characterize the secretome and protein secretion pathways of the rough-colony serotype a strain D7S. LC-MS/MS revealed 179 proteins secreted during biofilm growth. Further to confirming the release of established virulence factors (e.g. cytolethal distending toxin [CDT], and leukotoxin [LtxA]), we identified additional putative virulence determinants in the secretome. These included DegQ, fHbp, LppC, Macrophage infectivity protein (MIP), NlpB, Pcp, PotD, TolB, and TolC. This finding indicates that the number of extracellular virulence-related proteins is much larger than previously demonstrated, which was also supported by in silico analysis of the strain D7S genome. Moreover, our LC-MS/MS and in silico data revealed that at least Type I, II, and V secretion are actively used to excrete proteins directly into the extracellular space, or via two-step pathways involving the Sec/Tat systems for transport across the inner membrane, and outer membrane factors, secretins and auto-transporters, respectively for delivery across the outer membrane. Taken together, our results provide a molecular basis for further elucidating the role of A. actinomycetemcomitans in periodontal and systemic diseases.
authors: Oral Microbiology, Department of Odontology, Umeå University, Umeå, Sweden.
authors: Vincent
authors: V
authors: Zijnge
authors: Thomas
authors: T
authors: Kieselbach
authors: Jan
authors: J
authors: Oscarsson
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D015661:Pasteurellaceae / Q000166:cytology / Q000378:metabolism* / Q000472:pathogenicity; D021381:Protein Transport; D040901:Proteomics
chemical_list: D001426:Bacterial Proteins