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 k cat / K m and V max values of 4.8 ± 0.6 × 103 (mM−1·s−1) and 0.29 ± 0.02 (μM·s−1), K m of 15.6 ± 0.34 (μM), k cat 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. Image 1 • The whole genome of strain YC-XJ2 was sequenced, annotated and analyzed. • Aryl-OPFRs-degrading gene (sy-pte) was cloned and expressed. • Sy -PTE exhibited excellent adaptation to environmental conditions. • The enzymatic activity of Sy -PTE for TPhP was more than twice of Sb -PTE. • EHDPP was first reported to be degraded by phosphotriesterase (Sy -PTE). [ABSTRACT FROM AUTHOR]