An atypical phosphodiesterase capable of degrading haloalkyl phosphate diesters from Sphingobium sp. strain TCM1

Abstract

Sphingobium sp. strain TCM1 can degrade tris(2-chloroethyl) phosphate (TCEP) to inorganic phosphate and 2-chloroethanol. A phosphotriesterase (PTE), phosphodiesterase (PDE) and phosphomonoesterase (PME) are believed to be involved in the degradation of TCEP. The PTE and PME that respectively catalyze the first and third steps of TCEP degradation in TCM1 have been identified. However, no information has been reported on a PDE catalyzing the second step. In this study, we identified, purified, and characterized a PDE capable of hydrolyzing haloalkyl phosphate diesters. The final preparation of the enzyme had a specific activity of 29 µmol min−1 mg−1 with bis(p-nitrophenyl) phosphate (BpNPP) as the substrate. It also possessed low PME activity with p-nitrophenyl phosphate (pNPP) as substrate. The catalytic efficiency (k cat/K m) with BpNPP was significantly higher than that with pNPP, indicating that the enzyme prefers the organophosphorus diester to the monoester. The enzyme degraded bis(2,3-dibromopropyl) phosphate, bis(1,3-dichloro-2-propyl) phosphate and bis(2-chloroethyl) phosphate, suggesting that it is involved in the metabolism of haloalkyl organophosphorus triesters. The primary structure of the PDE from TCM1 is distinct from those of typical PDE family members and the enzyme belongs to the polymerase and histidinol phosphatase superfamily.

A Novel Alkaline Phosphatase/Phosphodiesterase, CamPhoD, from Marine Bacterium Cobetia amphilecti KMM 296

“…For comparison, the phosphodiesterases from Sphingobium sp. TCM1 and E. coli exhibited the maximal activity at pH 9.5 and 8.5-9.8, respectively [18,19]. with the activity of the enzyme, which was produced in the standard phosphate-free LB medium, similarly to the phoD phosphatase isolated from Streptomyces coelicolor [47].…”

“…For comparison, the phosphodiesterases from Sphingobium sp. TCM1 and E. coli exhibited the maximal activity at pH 9.5 and 8.5-9.8, respectively [18,19].…”

“…For comparison, the phosphodiesterases from Sphingobium sp. TCM1 and E. coli exhibited the maximal activity at pH 9.5 and 8.5-9.8, respectively [18,19]. The significant effect of KCl on the activity and the absence of activity without any salt in the incubation medium indicated that CamPhoD was a highly salt-tolerant enzyme, which is a common trait of many enzymes of marine origin [6,9,48,49].…”

“…Alkaline phosphodiesterases from Sphingobium sp. and Delftia acidovorans exhibit maximum activity at 55 °C and 65 °C, respectively [17,18].…”

“…The ability of CamPhoD to cleave the phosphate group of the diesters bis-pNPP and 5 -pNP-TMP, as well as different phosphate monoesters, allowed us to assign this enzyme to the bifunctional phosphatase/phosphodiesterase [9,10,[16][17][18][19][20]55]. For comparison, the binuclear zinc phosphodiesterase ZiPD from E. coli possessed activity towards phosphodiester bonds of bis-pNPP and 5 -pNP-TMP only, and did not catalyze the cleavage of other phosphates, such as AMP, ADP, ATP, cyclic phosphates, or nucleic acids [45].…”