Identification of Two Myrosinases from a Leclercia adecarboxylata Strain and Investigation of Its Tolerance Mechanism to Glucosinolate Hydrolysate

Abstract

Glucosinolates (GSLs), secondary metabolites synthesized by cruciferous plants, can be hydrolyzed by myrosinase into compounds, such as isothiocyanates (ITCs), with various bioactivities. Thus, myrosinase plays an important role in the utilization of GSLs. We isolated a bacterial strain, which was identified as Leclercia adecarboxylata, from the rhizosphere soil of rape seedlings and identified two myrosinase genes and an ITC hydrolase gene. Both myrosinases are intracellular and have 658 amino acid residues. Via molecular docking and chemical modification assays investigating the active sites of the myrosinases, arginine was found to be essential for their catalytic activity. Transcriptomic analysis of the response to sinigrin revealed significant up-regulation of some genes involved in allyl-ITC detoxification, with metallo-β-lactamase 3836 having the highest fold change. Thus, we discovered two myrosinases from L. adecarboxylata and demonstrated that the mechanism of tolerance of the bacterium to allyl-ITC likely involved metallo-β-lactamase activity.

A new source of bacterial myrosinase isolated from endophytic Bacillus sp. NGB-B10, and its relevance in biological control activity

“…However, we did not find any sequence similarity with myrosinase from Citrobacter sp. strain WYE1 (KT821094.1) or Leclercia adecarboxylata strain G1 (Tie et al 2021 ).…”

“…Although there are a large number of reports on bacteria with myrosinase-like activities that can metabolize GLs and produce bioactive compounds (Narbad and Rossiter 2018 ), identification of the myrosinase enzyme in these microorganisms is still limited to only a few studies. It is now documented that, myrosinase metabolic activity is not restricted to a single phylotype or a family of bacterial species (Albaser et al 2016 ; Wassermann et al 2017 ; Tie et al 2021 ; Cebeci et al 2022 ). In the present study , we isolated the bglA gene, one of the genes responsible for myrosinase activity, from Bacillus sp.…”

“…However, the bglA of the current study differs from other bacterial myrosinases belonging to glycoside hydrolase family 3 (GH3) which have been identified from Citrobacter sp. strain Wye1 (Albaser et al 2016 ; Cebeci et al 2022 ) and L. adecarboxylata strain G1 (Tie et al 2021 ). It has been reported that myrosinase enzymes corresponding to GH1 and GH3 differ in their properties and mechanisms of hydrolysis (Tie et al 2021 ).…”

“…strain Wye1 (Albaser et al 2016 ; Cebeci et al 2022 ) and L. adecarboxylata strain G1 (Tie et al 2021 ). It has been reported that myrosinase enzymes corresponding to GH1 and GH3 differ in their properties and mechanisms of hydrolysis (Tie et al 2021 ). Taken together, our data indicated that the GLs-metabolizing mechanism of Bacillus sp.…”

“…However, myrosinase has been also identified in insects (Jones et al 2001 ; Pontoppidan et al 2001 ), fungi (Rakariyatham et al 2005 ; Szucs et al 2018 ; Abdel-Fatah et al 2021 ), and human gut microbiota (Liou et al 2020 ; Sikorska-Zimny and Beneduce 2021 ). Many reports have described the isolation and characterization of myrosinase-producing strains belonging to diverse bacterial genera such as Bacillus (El-Shora et al 2016 ; Luang-In et al 2018 ), Companilactobacillus (Watanabe et al 2021 ) Citrobacter (Albaser et al 2016 ; Cebeci et al 2022 ), Enterobacter (Tani et al 1974 ; Wassermann et al 2017 ; Luang-In et al 2018 ), Enterococcus (Luang-In et al 2016 , 2018 ) , Lactobacillus (Palop et al 1995 ; Luang-In et al 2014 , 2016 ), Lactococcus (Mullaney et al 2013 ; Luang-In et al 2018 ), and Leclercia (Tie et al 2021 ) which are capable of in-vitro metabolism of GLs. Previous studies reported that the enzyme 6-phospho-β-glucosidase, encoded by the genes bglA , ascB , and chbF , is associated with myrosinase-like activity in bacteria such as Escherichia coli strain O157:H7 (Cordeiro et al 2015 ) and Enterobacter cloacae strain KS50 (Wassermann et al 2017 ) .…”