Abstract
N-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, ahlS, was present in the genomes of the CNS strains Staphylococcus carnosus, Staphylococcus haemolyticus, Staphylococcus saprophyticus, and Staphylococcus sciuri. We cloned the candidate ahlS 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 S. sciuri was expressed and purified as a maltose-binding protein (MBP) fusion. Pseudomonas aeruginosa 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 P. aeruginosa 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 P. aeruginosa PAO1.
Highlights
Quorum sensing is a cell-to-cell communication system used by many bacterial species depending on their population densities [1]
These results demonstrate that the Acylhomoserine lactones (AHLs)-degrading activity of AhlS from the Coagulase-negative staphylococci (CNS) strains can inhibit quorum sensing in P. aeruginosa PAO1
Strains was restored by acidification. These results indicated indicated that AhlS from the CNS strains worked as AHL‐lactonase, to other AiiA‐type that from the CNS strains worked as AHL-lactonase, to other AiiA-type AHL lactonases
Summary
Quorum sensing is a cell-to-cell communication system used by many bacterial species depending on their population densities [1]. One of the most common quorum-sensing signals, N-acyl-l-homoserine lactone (AHL), is used by Gram-negative bacteria [2]. Once the AHL reaches a threshold concentration, the transcription of specific genes is activated, resulting in the expression of phenotypes such as motility, adhesion, biofilm formation, toxicity, and pathogenicity [3]. AHL-negative mutants of many pathogens generally have defected pathogenicity [3,4]. Quorum quenching, which disrupts or manipulates quorum-sensing signals, is one of the most effective techniques to inhibit the expression of virulence and disrupt the infection of host cells. Many AHL-degrading enzymes have been cloned from various microorganisms and studied for their applications in the control of infectious diseases [5]
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