title: Role for the A domain of unprocessed accumulation-associated protein (Aap) in the attachment phase of the Staphylococcus epidermidis biofilm phenotype.
abstract: The polysaccharide intercellular adhesin or the cell wall-anchored accumulation-associated protein (Aap) mediates cellular accumulation during Staphylococcus epidermidis biofilm maturation. Mutation of sortase, which anchors up to 11 proteins (including Aap) to the cell wall, blocked biofilm development by the cerebrospinal fluid isolate CSF41498. Aap was implicated in this phenotype when Western blots and two-dimensional (2D) electrophoresis revealed increased levels of the protein in culture supernatants. Unexpectedly, reduced levels of primary attachment were associated with impaired biofilm formation by CSF41498 srtA and aap mutants. In contrast to previous studies, which implicated Aap proteolytic cleavage and, specifically, the Aap B domains in biofilm accumulation, the CSF41498 Aap protein was unprocessed. Furthermore, aap appeared to play a less important role in the biofilm phenotype of S. epidermidis 1457, in which the Aap protein is processed. Anti-Aap A-domain IgG inhibited primary attachment and biofilm formation in strain CSF41498 but not in strain 1457. The nucleotide sequences of the aap gene A-domain region and cleavage site in strains CSF41498 and 1457 were identical, implicating altered protease activity in the differential Aap processing results in the two strains. These data reveal a new role for the A domain of unprocessed Aap in the attachment phase of biofilm formation and suggest that extracellular protease activity can influence whether Aap contributes to the attachment or accumulation phases of the S. epidermidis biofilm phenotype.
authors.affiliation: School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Belfield, Dublin, Ireland Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Conlon
authors.affiliation: Department of Microbiology, Trinity College, Dublin, Ireland.
authors.forename: Joan A
authors.initials: JA
authors.lastname: Geoghegan
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Waters
authors.affiliation: Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
authors.forename: Hannah
authors.initials: H
authors.lastname: McCarthy
authors.affiliation: School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Belfield, Dublin, Ireland Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Rowe
authors.affiliation: Department of Oral Biology, Faculty of Odontology, Malmö University, Malmö, Sweden.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Davies
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Schaeffer
authors.affiliation: Department of Microbiology, Trinity College, Dublin, Ireland.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Foster
authors.affiliation: Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fey
authors.affiliation: School of Biomolecular and Biomedical Science and Conway Institute, University College Dublin, Belfield, Dublin, Ireland Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland jamesp.ogara@nuigalway.ie.
authors.forename: James P
authors.initials: JP
authors.lastname: O'Gara
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D015153:Blotting, Western; D002555:Cerebrospinal Fluid / Q000382:microbiology; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D009154:Mutation; D010641:Phenotype; D013212:Staphylococcus epidermidis / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins