Identification and Characterization of Quorum-Quenching Activity of <i>N</i>-Acylhomoserine Lactonase from Coagulase-Negative Staphylococci

• Main Authors: Tomohiro Morohoshi, Yaoki Kamimura, Nobutaka Someya
• Format: Article
• Language: English
• Published: MDPI AG 2020-08-01
• Series: Antibiotics
• Subjects: quorum sensing; <i>N</i>-acylhomoserine lactone; coagulase-negative staphylococci; AHL lactonase; <i>Pseudomonas aeruginosa</i>
• Online Access: https://www.mdpi.com/2079-6382/9/8/483

<i>N</i>-Acylhomoserine lactones (AHLs) are used as quorum-sensing signals in Gram-negative bacteria. Many genes encoding AHL-degrading enzymes have been cloned and characterized in various microorganisms. Coagulase-negative staphylococci (CNS) are present on the skin of animals and are considered low-virulent species. The AHL-lactonase gene homologue, <i>ahlS</i>, was present in the genomes of the CNS strains <i>Staphylococcus carnosus</i>, <i>Staphylococcus haemolyticus</i>, <i>Staphylococcus saprophyticus</i>, and <i>Staphylococcus sciuri</i>. We cloned the candidate <i>ahlS</i> homologue from six CNS strains into the pBBR1MCS5 vector. AhlS from the CNS strains showed a higher degrading activity against AHLs with short acyl chains compared to those with long acyl chains. AhlS from <i>S. sciuri</i> was expressed and purified as a maltose-binding protein (MBP) fusion. <i>Pseudomonas aeruginosa</i> is an opportunistic pathogen that regulates several virulence factors such as elastase and pyocyanin by quorum-sensing systems. When MBP-AhlS was added to the culture of <i>P. aeruginosa</i> PAO1, pyocyanin production and elastase activity were substantially reduced compared to those in untreated PAO1. These results demonstrate that the AHL-degrading activity of AhlS from the CNS strains can inhibit quorum sensing in <i>P. aeruginosa</i> PAO1.