The genome analysis of halotolerant Sphingobium yanoikuyae YC-XJ2 with aryl organophosphorus flame retardants degrading capacity and characteristics of related phosphotriesterase

The genome of Sphingobium yanoikuyae YC-XJ2 with aryl organophosphorus flame retardants (aryl-OPFRs) degrading activity was sequenced and analyzed systematically. The gene sy-pte was cloned and expressed, and the molecular mechanism of aryl-OPFRs degradation was elucidated. Sy-PTE exhibited enzymatic properties of alkali, high temperature and salt resistance. The hydrolyzation of EHDPP by phosphotriesterase was first reported. The specific activity of Sy-PTE was 67.0 ± 1.4 (U mg−1) for TPhP with kcat/Km and Vmax values of 4.8 ± 0.6 × 103 (mM−1·s−1) and 0.29 ± 0.02 (μM·s−1), Km of 15.6 ± 0.34 (μM), kcat of 75.02 ± 1.5 s−1, and need no metal ion activator to assist. The structural comparison of the metal binding sites with Sb-PTE (PDB ID 5HRM) showed that the transition from uncharged Met-259 to positively charged Asn-259 in Sy-PET might affect the binding of Mn2+ to His-258 because of the same electrical properties, and the transition from Gly-473 without side chains in Sb-PTE to Ala-473 might cause steric hindrance in binding of Mn2+ to His-475. Based on enzymatic advantages, Sy-PTE should be a promising engineered enzyme in the future for bioremediation of aryl-OPFRs polluted sites.