Haloalkylphosphorus Hydrolases Purified from Sphingomonas sp. Strain TDK1 and Sphingobium sp. Strain TCM1

Abstract

Phosphotriesterases catalyze the first step of organophosphorus triester degradation. The bacterial phosphotriesterases purified and characterized to date hydrolyze mainly aryl dialkyl phosphates, such as parathion, paraoxon, and chlorpyrifos. In this study, we purified and cloned two novel phosphotriesterases from Sphingomonas sp. strain TDK1 and Sphingobium sp. strain TCM1 that hydrolyze tri(haloalkyl)phosphates, and we named these enzymes haloalkylphosphorus hydrolases (TDK-HAD and TCM-HAD, respectively). Both HADs are monomeric proteins with molecular masses of 59.6 (TDK-HAD) and 58.4 kDa (TCM-HAD). The enzyme activities were affected by the addition of divalent cations, and inductively coupled plasma mass spectrometry analysis suggested that zinc is a native cofactor for HADs. These enzymes hydrolyzed not only chlorinated organophosphates but also a brominated organophosphate [tris(2,3-dibromopropyl) phosphate], as well as triaryl phosphates (tricresyl and triphenyl phosphates). Paraoxon-methyl and paraoxon were efficiently degraded by TCM-HAD, whereas TDK-HAD showed weak activity toward these substrates. Dichlorvos was degraded only by TCM-HAD. The enzymes displayed weak or no activity against trialkyl phosphates and organophosphorothioates. The TCM-HAD and TDK-HAD genes were cloned and found to encode proteins of 583 and 574 amino acid residues, respectively. The primary structures of TCM-HAD and TDK-HAD were very similar, and the enzymes also shared sequence similarity with fenitrothion hydrolase (FedA) of Burkholderia sp. strain NF100 and organophosphorus hydrolase (OphB) of Burkholderia sp. strain JBA3. However, the substrate specificities and quaternary structures of the HADs were largely different from those of FedA and OphB. These results show that HADs from sphingomonads are novel members of the bacterial phosphotriesterase family.

Draft Genome Sequences of Sphingobium sp. Strain TCM1 and Sphingomonas sp. Strain TDK1, Haloalkyl Phosphate Flame Retardant- and Plasticizer-Degrading Bacteria

“…These strains are considered to sequentially hydrolyze the three phosphoester bonds of TDCPP and TCEP using three kinds of phosphoesterases: phosphotriesterase (PTE), phosphodiesterase (PDE), and phosphomonoesterase (PME). We identified PTEs capable of degrading TDCPP and TCEP in both strains and named them haloalkylphosphorus hydrolase (HAD) ( 4 ). However, PDEs and PMEs involved in the degradation have not yet been identified.…”

Direct effects of organic pollutants on the growth and gene expression of the Baltic Sea model bacteriumRheinheimerasp.BAL341

“…The OPs used in our MIX treatment are proven to be degradable and hence can be used as a resource for bacteria (Leahy and Colwell, ; Takahashi et al ., , , , ; Seo et al ., ; Abe et al ., , ; Joye et al ., ; Kera et al ., ; Vila‐Costa et al ., )). Yet, our study showed notably negative effects on bacterial growth of hydrocarbons and OPEs supplied at environmentally relevant concentrations.…”

Organophosphate-degrading metallohydrolases: Structure and function of potent catalysts for applications in bioremediation

“…strain TCM1 (i.e. Sb-PTE) is of interest [102]. These enzymes are particularly reactive toward a group of OP triesters that are frequently used as plasticizers, durable plastics, foams and flame retardants.…”