Nucleases from <i>Prevotella intermedia</i> can degrade neutrophil extracellular traps

<jats:title>Summary</jats:title><jats:p>Periodontitis is an inflammatory disease caused by periodontal bacteria in subgingival plaque. These bacteria are able to colonize the periodontal region by evading the host immune response. Neutrophils, the host's first line of defense against infection, use various strategies to kill invading pathogens, including neutrophil extracellular traps (<jats:styled-content style="fixed-case">NET</jats:styled-content>s). These are extracellular net‐like fibers comprising <jats:styled-content style="fixed-case">DNA</jats:styled-content> and antimicrobial components such as histones, <jats:styled-content style="fixed-case">LL</jats:styled-content>‐37, defensins, myeloperoxidase, and neutrophil elastase from neutrophils that disarm and kill bacteria extracellularly. Bacterial nuclease degrades the <jats:styled-content style="fixed-case">NET</jats:styled-content>s to escape <jats:styled-content style="fixed-case">NET</jats:styled-content> killing. It has now been shown that extracellular nucleases enable bacteria to evade this host antimicrobial mechanism, leading to increased pathogenicity. Here, we compared the <jats:styled-content style="fixed-case">DNA</jats:styled-content> degradation activity of major Gram‐negative periodontopathogenic bacteria, <jats:italic>Porphyromonas gingivalis</jats:italic>,<jats:italic> Prevotella intermedia</jats:italic>,<jats:italic> Fusobacterium nucleatum</jats:italic>, and <jats:italic>Aggregatibacter actinomycetemcomitans</jats:italic>. We found that <jats:italic>Pr. intermedia</jats:italic> showed the highest <jats:styled-content style="fixed-case">DNA</jats:styled-content> degradation activity. A genome search of <jats:italic>Pr. intermedia</jats:italic> revealed the presence of two genes, <jats:italic>nucA</jats:italic> and <jats:italic>nucD</jats:italic>, putatively encoding secreted nucleases, although their enzymatic and biological activities are unknown. We cloned <jats:italic>nucA</jats:italic>‐ and <jats:italic>nucD</jats:italic>‐encoding nucleases from <jats:italic>Pr. intermedia </jats:italic><jats:styled-content style="fixed-case">ATCC</jats:styled-content> 25611 and characterized their gene products. Recombinant NucA and NucD digested <jats:styled-content style="fixed-case">DNA</jats:styled-content> and <jats:styled-content style="fixed-case">RNA</jats:styled-content>, which required both Mg<jats:sup>2+</jats:sup> and Ca<jats:sup>2+</jats:sup> for optimal activity. In addition, NucA and NucD were able to degrade the <jats:styled-content style="fixed-case">DNA</jats:styled-content> matrix comprising <jats:styled-content style="fixed-case">NET</jats:styled-content>s.</jats:p>