title: The BR domain of PsrP interacts with extracellular DNA to promote bacterial aggregation; structural insights into pneumococcal biofilm formation.
abstract: The major human pathogen Streptococcus pneumoniae is a leading cause of disease and death worldwide. Pneumococcal biofilm formation within the nasopharynx leads to long-term colonization and persistence within the host. We have previously demonstrated that the capsular surface-associated pneumococcal serine rich repeat protein (PsrP), key factor for biofilm formation, binds to keratin-10 (KRT10) through its microbial surface component recognizing adhesive matrix molecule (MSCRAMM)-related globular binding region domain (BR187-385). Here, we show that BR187-385 also binds to DNA, as demonstrated by electrophoretic mobility shift assays and size exclusion chromatography. Further, heterologous expression of BR187-378 or the longer BR120-378 construct on the surface of a Gram-positive model host bacterium resulted in the formation of cellular aggregates that was significantly enhanced in the presence of DNA. Crystal structure analyses revealed the formation of BR187-385 homo-dimers via an intermolecular β-sheet, resulting in a positively charged concave surface, shaped to accommodate the acidic helical DNA structure. Furthermore, small angle X-ray scattering and circular dichroism studies indicate that the aggregate-enhancing N-terminal region of BR120-166 adopts an extended, non-globular structure. Altogether, our results suggest that PsrP adheres to extracellular DNA in the biofilm matrix and thus promotes pneumococcal biofilm formation.
authors: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Department of Infectious Diseases, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
authors: Tim
authors: T
authors: Schulte
authors: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Department of Infectious Diseases, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
authors: Cecilia
authors: C
authors: Mikaelsson
authors: Université catholique de Louvain, Institute of Life Sciences, Croix du Sud, 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium.
authors: Audrey
authors: A
authors: Beaussart
authors: European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22603 Hamburg, Germany.
authors: Alexey
authors: A
authors: Kikhney
authors: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Department of Infectious Diseases, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
authors: Maya
authors: M
authors: Deshmukh
authors: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Department of Infectious Diseases, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
authors: Sebastian
authors: S
authors: Wolniak
authors: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute; Clinical Microbiology, Karolinska University Hospital Solna, Stockholm, Sweden.
authors: Anuj
authors: A
authors: Pathak
authors: Institut de Biologie Structurale (IBS), Univ. Grenoble Alpes, CEA, CNRS, 38044 Grenoble, France.
authors: Christine
authors: C
authors: Ebel
authors: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute; Clinical Microbiology, Karolinska University Hospital Solna, Stockholm, Sweden.
authors: Jonas
authors: J
authors: Löfling
authors: Dipartimento di Scienze Mediche e Biologiche, Universita' di Udine, Piazzale Kolbe 4, 33100 Udine - Italy.
authors: Federico
authors: F
authors: Fogolari
authors: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institute; Clinical Microbiology, Karolinska University Hospital Solna, Stockholm, Sweden.
authors: Birgitta
authors: B
authors: Henriques-Normark
authors: Université catholique de Louvain, Institute of Life Sciences, Croix du Sud, 4-5, bte L7.07.06, B-1348 Louvain-la-Neuve, Belgium.
authors: Yves F
authors: YF
authors: Dufrêne
authors: European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22603 Hamburg, Germany.
authors: Dmitri
authors: D
authors: Svergun
authors: Division of Protein Technology, School of Biotechnology, KTH-Royal, Institute of Technology, Sweden.
authors: Per-Åke
authors: PÅ
authors: Nygren
authors: Science for Life Laboratory, Department of Medicine Solna, Karolinska Institute, and Department of Infectious Diseases, Karolinska University Hospital, Solna, SE-17176 Stockholm, Sweden.
authors: Adnane
authors: A
authors: Achour
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D002462:Cell Membrane / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D045683:Furin / Q000378:metabolism; D015870:Gene Expression; D009690:Nucleic Acid Conformation; D000072417:Protein Domains; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D053838:Scattering, Small Angle; D013296:Streptococcus pneumoniae / Q000166:cytology* / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D045683:Furin