High Expression Level of mok E Enhances the Production of Monacolin K in Monascus

ABSTRACT

Monacolin K (MK) is a type of cholesterol-lowering agent produced by Monascus spp. The expression level of the mok E gene, a gene of the MK biosynthesis gene cluster, was previously speculated to be positively correlated with the production of MK. In this study, mok E was overexpressed in Monascus fuliginosusis CG-6. The expression levels were analyzed by RT-qPCR. Genome walking was used to analyze the insertion site of the exogenous gene. Results showed that MK production in transformants T-mok E1 (4083.2 μg/g), T-mok E2 (6186.3 μg/g), and T-mok E3 (4527.6 μg/g) was 1.7-fold, 2.5-fold, and 1.8-fold higher than that of the wild strain CG-6 (2469.8 μg/g), respectively. The expression level of mok E in T-mok E1, T-mok E2, and T-mok E3 was 1.83-fold, 4.82-fold, and 2.22-fold higher than that in the wild-type strain (WS CG-6), respectively. The AAA ATPase gene located upstream and acetyl-CoA synthetase gene located downstream of the insertion were obtained by genome walking. These results indicate that the expression of the mok E gene was positively correlated with the production of MK. The expression levels of the AAA ATPase gene and acetyl-CoA synthetase gene were enhanced by the insertion of an exogenous gene.

KEYWORDS:

• Genome walking
• mok E gene
• Monacolin K
• Monascus fuliginosus CG-6
• overexpression
• RT-qPCR

Acknowledgments

This work was supported by the National Natural Science Foundation of China (Grant No. 31330059).