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Identification of a novel DNase of Streptococcus suis (EndAsuis) important for neutrophil extracellular trap degradation during exponential growth

de Buhr, Nicole; Stehr, Matthias; Neumann, Ariane LU ; Naim, Hassan Y.; Valentin-Weigand, Peter; von Köckritz-Blickwede, Maren and Baums, Christoph G (2015) In Microbiology 161. p.50-838
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... (More)

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.

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author
publishing date
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Contribution to journal
publication status
published
keywords
Amino Acid Sequence, Bacterial Proteins, Deoxyribonucleases, Endodeoxyribonucleases, Extracellular Traps, Gene Expression Regulation, Bacterial, Hydrogen-Ion Concentration, Ions, Membrane Proteins, Models, Molecular, Molecular Sequence Data, Mutation, Neutrophils, Protein Conformation, RNA, Messenger, Sequence Alignment, Streptococcal Infections, Streptococcus suis, Journal Article, Research Support, Non-U.S. Gov't
in
Microbiology
volume
161
pages
13 pages
publisher
MAIK Nauka/Interperiodica
external identifiers
  • scopus:84991236019
ISSN
1465-2080
DOI
10.1099/mic.0.000040
language
English
LU publication?
no
id
0f55e87b-f613-4f3a-9b01-17663f0a9286
date added to LUP
2017-09-19 12:22:47
date last changed
2017-09-24 05:15:36
@article{0f55e87b-f613-4f3a-9b01-17663f0a9286,
  abstract     = {<p>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.</p>},
  author       = {de Buhr, Nicole and Stehr, Matthias and Neumann, Ariane and Naim, Hassan Y. and Valentin-Weigand, Peter and von Köckritz-Blickwede, Maren and Baums, Christoph G},
  issn         = {1465-2080},
  keyword      = {Amino Acid Sequence,Bacterial Proteins,Deoxyribonucleases,Endodeoxyribonucleases,Extracellular Traps,Gene Expression Regulation, Bacterial,Hydrogen-Ion Concentration,Ions,Membrane Proteins,Models, Molecular,Molecular Sequence Data,Mutation,Neutrophils,Protein Conformation,RNA, Messenger,Sequence Alignment,Streptococcal Infections,Streptococcus suis,Journal Article,Research Support, Non-U.S. Gov't},
  language     = {eng},
  pages        = {50--838},
  publisher    = {MAIK Nauka/Interperiodica},
  series       = {Microbiology},
  title        = {Identification of a novel DNase of Streptococcus suis (EndAsuis) important for neutrophil extracellular trap degradation during exponential growth},
  url          = {http://dx.doi.org/10.1099/mic.0.000040},
  volume       = {161},
  year         = {2015},
}