A novel malic enzyme gene, Mime2, from Mortierella isabellina M6-22 contributes to lipid accumulation

作者：Li, Shan; Li, Lingyan; Xiong, Xiangfeng; Ji, Xiuling; Wei, Yunlin; Lin, Lianbing; Zhang, Qi^*

来源：Biotechnology Letters, 2018, 40(7): 1109-1118.

DOI：10.1007/s10529-018-2560-1

• Mortierella isabellina
• Malic enzyme
• Lipid
• Rhodosporidium kratochvilovae

This study was aimed at cloning and characterizing a novel malic enzyme (ME) gene of Mortierella isabellina M6-22 and identifying its relation with lipid accumulation.
Mime2 was cloned from strain M6-22. Plasmid pET32aMIME2 was constructed to express ME of MIME2 in Escherichia coli BL21. After purification, the optimal pH and temperature of MIME2, as well as K-m and V-max for NADP(+) were determined. The effects of EDTA or metal ions (Mn2+, Mg2+, Co2+, Cu2+, Ca2+, or Zn2+) on the enzymatic activity of MIME2 were evaluated. Besides, plasmid pRHMIME2 was created to express MIME2 in Rhodosporidium kratochvilovae YM25235, and its cell lipid content was measured by the acid-heating method. The optimal pH and temperature of MIME2 are 5.8 and 30 A degrees C, respectively.
The act ivity of MIME2 was significantly increased by Mg2+, Ca2+, or Mn2+ at 0.5 mM but inhibited by Cu2+ or Zn2+ (p < 0.05). The optimal enzymatic activity of MIME2 is 177.46 U/mg, and the K-m and V-max for NADP(+) are 0.703 mM and 156.25 mu g/min, respectively. Besides, Mime2 transformation significantly increased the cell lipid content in strain YM25235 (3.15 +/- 0.24 vs. 2.17 +/- 0.31 g/L, p < 0.01).
The novel ME gene Mime2 isolated from strain M6-22 contributes to lipid accumulation in strain YM25235.

• 出版日期2018-7
• 单位昆明理工大学