Nuclease A (Gbs0661), an extracellular nuclease of Streptococcus agalactiae,attacks the neutrophil extracellular traps and is needed for full virulence |
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Authors: | Aurélie Derré‐Bobillot Naima G. Cortes‐Perez Yuji Yamamoto Pascale Kharrat Elizabeth Couvé Violette Da Cunha Patrice Decker Marie‐Christophe Boissier Frédéric Escartin Bénédicte Cesselin Philippe Langella Luis G. Bermúdez‐Humarán Philippe Gaudu |
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Affiliation: | 1. INRA, UMR1319 Micalis, , F‐78350 Jouy‐en‐Josas, France;2. AgroParisTech, UMR Micalis, , F‐78350 Jouy‐en‐Josas, France;3. Unité de Génétique des Génomes Bactériens, Institut Pasteur, CNRS URA 2171, , 75724 Paris cedex 15, France;4. Université Paris 13, , EA4222, Li2P Bobigny, France;5. H?pital Avicenne, Département de Rhumatologie, , AP‐HP Bobigny, France |
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Abstract: | Most bacteria of the genus Streptococcus are opportunistic pathogens, and some of them produce extracellular DNases, which may be important for virulence. Genome analyses of Streptococcus agalactiae (GBS) neonate isolate NEM316 revealed the presence of seven genes putatively encoding secreted DNases, although their functions, if any, are unknown. In this study, we observed that respiration growth of GBS led to the extracellular accumulation of a putative nuclease, identified as being encoded by the gbs0661 gene. When overproduced in Lactococcus lactis, the protein was found to be a divalent cation‐requiring, pH‐stable and heat‐stable nuclease that we named Nuclease A (NucA). Substitution of the histidine148 by alanine reduced nuclease activity of the GBS wild‐type strain, indicating that NucA is the major nuclease ex vivo. We determined that GBS is able to degrade the DNA matrix comprising the neutrophil extracellular trap (NET). The nucAH148A mutant was impaired for this function, implicating NucA in the virulence of GBS. In vivo infection studies confirmed that NucA is required for full infection, as the mutant strain allowed increased bacterial clearance from lung tissue and decreased mortality in infected mice. These results show that NucA is involved in NET escape and is needed for full virulence. |
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