| 论文标题： |
Heterologous expression of mlrA gene originated from Novosphingobium sp THN1 to degrade microcystin-RR and identify the first step involved in degradation pathway |
| 作者： |
Wang, Ruiping; Li, Jieming; Jiang, Yongguang; Lu, Zhijiang; Li, Renhui; Li, Ji |
| 出版刊物： |
CHEMOSPHERE |
| 出版日期： |
OCT |
| 出版年份： |
2017 |
| 卷/期： |
|
| DOI： |
10.1016/j.chemosphere.2017.05.086 |
| 论文摘要： |
Information on the catalytic role of mlrA gene-encoded enzyme (MlrA) in microcystin-RR (MC-RR) biodegradation was limited. This study succeeded in expressing mlrA homolog of Novosphingobium sp. THN1 in heterologous host for the first time, by constructing a recombinant bacterium. Mass spectrometric analysis showed that the recombinant MlrA hydrolyzed MC-RR into linear intermediate product by cleaving the peptide bond between Adda and arginine residue, greatly detoxifying MC-RR. This finding clearly manifested that the MlrA homolog of THN1 strain possesses its original catalytic function, and ring-opening constituted the first step in MC-RR biodegradation pathway of THN1 strain. Moreover, MC-RR degradation by intact recombinant cells and cell-free crude enzyme (CE) from recombinant was compared. Results exhibited that intact recombinant was able to degrade 20 mu g mL(-1) MC-RR more quickly than CE, with the maximum rate of 9.22 mu g mL(-1) h(-1) in the first 8 h. Thus, this study provided new insights on the catalytic activity and roles of MIrA originated from THN1 strain in MC-RR biodegradation process, which lay a foundation for efficiently removing and detoxifying MC-RR, and exploring downstream steps in MC-RR biodegradation pathway of THN1 strain. (C) 2017 Elsevier Ltd. All rights reserved. |
