PfmA, a novel quorum-quenching N-acylhomoserine lactone acylase from Pseudoalteromonas flavipulchra

Abstract

Many bacteria, such as Proteobacteria, Cyanobacteria and Bacteroidetes, use N-acylhomoserine lactones (AHLs) as quorum-sensing (QS) signal molecules for communication. Enzymatic degradation of AHLs, such as AHL acylase and AHL lactonase, can degrade AHLs (quorum quenching, QQ) to attenuate or disarm the virulence of pathogens. QQ is confirmed to be common in marine bacterial communities. Many genes encoding AHL acylases are found in marine bacteria and metagenomic collections, but only a few of these have been characterized in detail. We have reported that the marine bacterium Pseudoalteromonas flavipulchra JG1 can degrade AHLs. In the present study, a novel AHL acylase PfmA, which can degrade AHLs with acyl chains longer than 10 carbons, was identified from strain JG1. Ultra-performance liquid chromatography (UPLC) and electrospray ionization mass spectrometry (ESI-MS) analysis demonstrated that PfmA functions as an AHL acylase, which hydrolysed the amide bond of AHL. The purified PfmA of P. flavipulchra JG1 showed optimum activity at 30 °C and pH 7.0. PfmA belongs to the N-terminal nucleophile (Ntn) hydrolase superfamily and showed homology to a member of penicillin amidases, but PfmA can degrade ampicillin but not penicillin G. The residue Ser256 in PfmA is the active site according to site-directed mutagenesis. Furthermore, PfmA reduced AHL accumulation and the production of virulence factors in Vibrio anguillarum VIB72 and Pseudomonas aeruginosa PAO1, and attenuated the virulence of P. aeruginosa to increase Artemia survival, which suggested that PfmA can be considered as a therapeutic agent to control AHL-mediated pathogenicity.

Discovering, Characterizing, and Applying Acyl Homoserine Lactone-Quenching Enzymes to Mitigate Microbe-Associated Problems Under Saline Conditions

“…Similarly, we found four homologous QQ ORFs in L11. Both PvdQ L11 and HP L11 shared 24% and 48% of their identity with the reported pfmA and QQ-16d enzymes from the same genera (Weiland-Bräuer et al, 2015; Liu et al, 2017). However, a further examination of each of the individual purified enzymes from L11 showed that only SDRL 11 was positive for AHL quenching activity.…”

“…In comparison, QQ enzymes that degrade extracellular QS signals are viewed as imposing less of a burden on cellular metabolism (Fetzner, 2015), and hence, they minimize the development of resistance toward these greener inhibitory agents. In most instances, QQ enzymes or bacteria with enzymatic activity from marine sources (Huang et al, 2012; Mayer et al, 2015; Tang et al, 2015; Liu et al, 2017; Rehman and Leiknes, 2018) were demonstrated for their efficiencies to quench QS in only minimal or nutrient medium, which deviate significantly from conditions in marine industrial systems such as seawater desalination plants (salinity: 46,400 ppm, temperature: 22–33°C, and pH 8.1–8.3) (Khawaji et al, 2007) and cooling towers (e.g., salinity: >35,000 ppm, and temperature 32–48°C) (Al-Bloushi et al, 2018).…”

Engineering quorum quenching enzymes: progress and perspectives

“…While naturally occurring quorum quenching enzymes have shown promising effects both in vitro and in vivo [10,11], protein engineering approaches are being explored to further improve the stability, catalytic activity and/or substrate specificity of these enzymes for downstream applications.…”

Saline Environments as a Source of Potential Quorum Sensing Disruptors to Control Bacterial Infections: A Review

“…Although QQ of AI-2-type molecules has recently been reported [113], most studies have focused on the degradation of AHLs. Indeed, QQ enzymes having AHL signals as substrates have been described in many marine species, such as Alteromonas stellipolaris, A. genovensis, Pseudoalteromonas paragorgicola, P. tetraodonis, P. carrageenovora, P. atlantica, P. distincta [104]; P. flavipulchra [241]; A. marina, Thalassomonas agariperforans, Paracoccus homiensis [106]; Muricauda olearia [242]; Tenacibaculum maritimum [243]; Roseovarius aestuarii, Rhodococcus erythropolis, Salinicola salarius [214]; Ruegeria mobilis [244]; Stenotrophomonas maltophilia [105]; Maribacter ulvicola, Olleya marilimosa [111]; Planococcus sp. [245] and Bacillus sp.…”

“…Interestingly, searches for QQ enzymes in such collections revealed that acylases might be more abundant than lactonases [111,215], in agreement with the results obtained for cultivable bacteria. For instance, acylases have been described in Alteromonas stellipolaris [104], Pseudomonas flavipulchra [241], Shewanella sp. [247] , Oceanobacillus sp.…”