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Biotechnol Lett. 2018 Jul;40(7):1109-1118. doi: 10.1007/s10529-018-2560-1. Epub 2018 May 18.

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

Author information

1
Faculty of Life Science and Technology, Kunming University of Science and Technology, 727 South Jingming Road, Kunming, 650500, Yunnan, China.
2
Faculty of Life Science and Technology, Kunming University of Science and Technology, 727 South Jingming Road, Kunming, 650500, Yunnan, China. qzhang37@gmail.com.

Abstract

OBJECTIVE:

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.

METHODS:

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 Km and Vmax 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 °C, respectively.

RESULTS:

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 Km and Vmax for NADP+ are 0.703 mM and 156.25 μg/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).

CONCLUSIONS:

The novel ME gene Mime2 isolated from strain M6-22 contributes to lipid accumulation in strain YM25235.

KEYWORDS:

Lipid; Malic enzyme; Mortierella isabellina; Rhodosporidium kratochvilovae

PMID:
29777513
DOI:
10.1007/s10529-018-2560-1
[Indexed for MEDLINE]

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