Enhancement of enzyme activity and thermostability of Nacylhomoserine lactonase by site-directed mutagenesis

Abstract:

Abstract:［Objective］ To enhance enzymatic activity and thermostability of N-acylhomoserine lactonase (AiiA)．［Methods］ We performed site-directed mutagenesis based on AiiA homologous 3-D protein structure，and analyzed enzymatic activity and thermostability of both wild type and mutated AiiA．［Results］ The wild type AiiA lost its Nacylhomoserine lactone (AHL) degrading activity after being incubated at 45℃ for 30 min or after being stored at 4℃ for 5 days．By comparison，the AHL-degrading activities of three types of mutated AiiA (N65K，T195Ｒ，and A206E) were enhanced，and their storage periods at 4℃ were extended to 7 days．In addition，the N65K mutant acquired higher temperature tolerance with remain of more than 45% of its enzymatic activity after being incubated at 45℃ and 5.0% enzymatic activity after being incubated at 55℃ as compared to the wild type．［Conclusion］Molecular modulation by site-directed mutagenesis could significantly improve enzymatic activity and thermostability of AiiA．

Key words:Keywords: N-acylhomoserine lactone，N-acylhomoserine lactonase，enzymatic characterization，site-directed mutagenesis