Biosynthesis of polyketides by two type III polyketide synthases from Aloe barbadensis

Abstract

Various bioactive polyketides have been found in Aloe barbadensis. However, the polyketide synthases (PKSs), which participate in biosynthesis of polyketides in A. barbadensis remain unknown. In this study, two type III PKSs (AbPKS1 and AbPKS2) were identified from A. barbadensis. AbPKS1 and AbPKS2 were able to utilize malonyl-CoA to yield heptaketides (TW93a and aloesone) and octaketides (SEK4 and SEK4b), respectively. AbPKS1 also exhibited catalytic promiscuity in recognizing CoA thioesters of aromatics to produce unusual polyketides. What Is more, a whole cell biocatalysis system with the capability of producing 26.4 mg/L of SEK4/SEK4b and 2.1 mg/L of aloesone was successfully established.

Graphical Abstract

Keywords:

• Aloe barbadensis
• polyketides
• type III PKS
• whole cell catalyst

Acknowledgments

The authors wish to thank Prof. Shepo Shi of Beijing University of Chinese Medicine for his generous gifts of matB and At4CL genes.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by National Natural Science Foundation of China (No. 81602999 and No. 81573317), CAMS Innovation Fund for Medical Sciences (CIFMS-2016-I2M-3-012), the Drug Innovation Major Project (2018ZX09711001-006), and the Fundamental Research Funds for the Central Universities (2017PT35001).