title: Identification of a novel DNase of Streptococcus suis (EndAsuis) important for neutrophil extracellular trap degradation during exponential growth.
abstract: The porcine and human pathogen Streptococcus suis induces and degrades neutrophil extracellular traps (NETs) in vitro. In this study, we investigated the working hypothesis that NET degradation is mediated not only by the known secreted S. suis nuclease A (SsnA) but also by a so-far undescribed putative endonuclease A of S. suis (designated EndAsuis) homologous to the pneumococcal endonuclease A (EndA). Comparative analysis was conducted to identify differences in localization, expression and function of EndAsuis and SsnA. In contrast to ssnA, endAsuis RNA expression was not substantially different during exponential and stationary growth. Modelling of the 3D structure confirmed a putative DRGH-motif-containing ββα-metal finger catalytic core in EndAsuis. Accordingly, nuclease activity of recombinant EndAsuis with a point-mutated H165 was rescued through imidazol treatment. In accordance with a putative membrane anchor, nuclease activity caused by endAsuis was not detectable in the supernatant. Importantly, endAsuis determined nuclease activity of S. suis prominently during exponential growth. This activity depended on the presence of Mg(2+) but, in contrast to SsnA activity, not on Ca(2+). A pH of 5.4 did not inhibit endAsuis-encoded nuclease activity during exponential growth. NET degradation of S. suis harvested during exponential growth was significantly attenuated in the endAsuis mutant. In contrast to SsnA, mutagenesis of endAsuis did not result in a significantly higher susceptibility against the antimicrobial effect mediated by NETs. As degradation of bacterial DNA caused by S. suis depended on ssnA and endAsuis, further functions of both factors in the host-pathogen interaction might be envisioned.
authors: Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Nicole
authors: N
authors: de Buhr
authors: Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany LIONEX Diagnostics and Therapeutics GmbH, Braunschweig, Germany.
authors: Matthias
authors: M
authors: Stehr
authors: Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Ariane
authors: A
authors: Neumann
authors: Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Hassan Y
authors: HY
authors: Naim
authors: Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Peter
authors: P
authors: Valentin-Weigand
authors: Department of Physiological Chemistry, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Maren
authors: M
authors: von Köckritz-Blickwede
authors: Institute for Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany Institute for Bacteriology and Mycology, Centre for Infectious Diseases, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany christoph.baums@vetmed.uni-leipzig.de.
authors: Christoph G
authors: CG
authors: Baums
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism; D003851:Deoxyribonucleases / Q000737:chemistry / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000737:chemistry / Q000378:metabolism; D065206:Extracellular Traps / Q000276:immunology* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism*; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D013290:Streptococcal Infections / Q000382:microbiology*; D017011:Streptococcus suis / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D007477:Ions; D008565:Membrane Proteins; D012333:RNA, Messenger; D003851:Deoxyribonucleases; D004706:Endodeoxyribonucleases; C064668:endA protein, bacteria