TY - JOUR ID - 10.1016/S1001-0742(11)61016-4 TI - Cloning and expression of the first gene for biodegrading microcystin LR by Sphingopyxis sp. USTB-05 AU - Hai Yan AU - Huasheng Wang AU - Junfeng Wang AU - Chunhua Yin AU - Song Ma AU - Xiaolu Liu and Xueyao Yin VL - 24 IS - 10 PB - SP - 1816 EP - 1822 PY - JF - Journal of Environmental Sciences JA - J. Environ. Sci. UR - http://www.jesc.ac.cn/jesc_en/ch/reader/view_abstract.aspx?file_no=2012241013&flag=1 KW - microcystin LR;Sphingopyxis sp. USTB-05;biodegradation;gene KW - microcystin LR;Sphingopyxis sp. USTB-05;biodegradation;gene AB - Harmful cyanobacterial blooms are a growing environmental problem worldwide in natural waters, the biodegradation is found to be the most efficient method for removing microcystins (MCs) produced by harmful cyanobacteria. Based on the isolation of a promising bacterial strain of Sphingopyxis sp. USTB-05 for biodegrading MCs, we for the first time cloned and expressed a gene USTB-05-A (HM245411) that is responsible for the first step in the biodegradation of microcystin LR (MC-LR) in E. coli DH5α, with a cloning vector of pGEM-T easy and an expression vector of pGEX-4T-1, respectively. The cell-free extracts (CE) of recombinant E. coli DH5α containing USTB-05-A had high activity for biodegrading MC-LR. The initial MC-LR concentration of 40 mg/L was completely biodegraded within 1 hr in the presence of CE with a protein concentration of 0.35 mg/mL. Based on an analysis of the liquid chromatogram-mass spectrum (LC-MS), the enzyme encoded by gene USTB-05-A was found to be active in cleaving the target peptide bond between 3-amino-9-methoxy-2,6, 8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda) and arginine of MC-LR, and converting cyclic MC-LR to linear MC-LR as a first product that is much less toxic than parent MC-LR, which offered direct evidence for the first step on the pathway of MC-LR biodegradation by Sphingopyxis sp. USTB-05. ER -