title: The N-terminal repeat and the ligand binding domain A of SdrI protein is involved in hydrophobicity of S. saprophyticus.
abstract: Staphylococcus saprophyticus is an important cause of urinary tract infection, and its cell surface hydrophobicity may contribute to virulence by facilitating adherence of the organism to uroepithelia. S. saprophyticus expresses the surface protein SdrI, a member of the serine-aspartate repeat (SD) protein family, which has multifunctional properties. The SdrI knock out mutant has a reduced hydrophobicity index (HPI) of 25%, and expressed in the non-hydrophobic Staphylococcus carnosus strain TM300 causes hydrophobicity. Using hydrophobic interaction chromatography (HIC), we confined the hydrophobic site of SdrI to the N-terminal repeat region. S. saprophyticus strains carrying different plasmid constructs lacking either the N-terminal repeats, both B or SD-repeats were less hydrophobic than wild type and fully complemented SdrI mutant (HPI: 51%). The surface hydrophobicity and HPI of both wild type and the complemented strain were also influenced by calcium (Ca(2+)) and were reduced from 81.3% and 82.4% to 10.9% and 12.3%, respectively. This study confirms that the SdrI protein of S. saprophyticus is a crucial factor for surface hydrophobicity and also gives a first significant functional description of the N-terminal repeats, which in conjunction with the B-repeats form an optimal hydrophobic conformation.
authors.affiliation: Institut für Hygiene und Mikrobiologie, Abteilung für Medizinische Mikrobiologie, Ruhr-Universität Bochum, D-44780 Bochum, Germany. Electronic address: b.j.kleine@gmx.de.
authors.forename: Britta
authors.initials: B
authors.lastname: Kleine
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, 79106 Freiburg, Germany; Faculty of Biology, Albert Ludwigs University of Freiburg, 79104 Freiburg, Germany. Electronic address: liaqatbiotech@yahoo.com.
authors.forename: Liaqat
authors.initials: L
authors.lastname: Ali
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, 79106 Freiburg, Germany. Electronic address: dominique.wobser@uniklinik-freiburg.de.
authors.forename: Dominique
authors.initials: D
authors.lastname: Wobser
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine II, University Hospital Freiburg, 79106 Freiburg, Germany. Electronic address: tuerkan.sakinc@uniklinik-freiburg.de.
authors.forename: Türkân
authors.initials: T
authors.lastname: Sakιnç
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D015870:Gene Expression; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D017434:Protein Structure, Tertiary; D057790:Staphylococcus saprophyticus / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins
keywords: Hydrophobicity; Repeats; SdrI; Staphylococcus saprophyticus; UTI