Designing microorganisms for heterologous biosynthesis of cannabinoids

Abstract

During the last decade, the use of medical Cannabis has expanded globally and legislation is getting more liberal in many countries, facilitating the research on cannabinoids. The unique interaction of cannabinoids with the human endocannabinoid system makes these compounds an interesting target to be studied as therapeutic agents for the treatment of several medical conditions. However, currently there are important limitations in the study, production and use of cannabinoids as pharmaceutical drugs. Besides the main constituent tetrahydrocannabinolic acid, the structurally related compound cannabidiol is of high interest as drug candidate. From the more than 100 known cannabinoids reported, most can only be extracted in very low amounts and their pharmacological profile has not been determined. Today, cannabinoids are isolated from the strictly regulated Cannabis plant, and the supply of compounds with sufficient quality is a major problem. Biotechnological production could be an attractive alternative mode of production. Herein, we explore the potential use of synthetic biology as an alternative strategy for synthesis of cannabinoids in heterologous hosts. We summarize the current knowledge surrounding cannabinoids biosynthesis and present a comprehensive description of the key steps of the genuine and artificial pathway, systems biotechnology needs and platform optimization.

Keywords: Cannabis sativa; Saccharomyces cerevisiae; biotechnology; cannabinoids; synthetic biology.

Figure 1.

Isoprenoid formation in S. cerevisiae. The isoprenoid biosynthesis starts with acetyl-CoA, which is derived from the glycolytic pathway. At the end of the MVA, the both isoprenoids IPP and DMAPP are formed. Subsequently, GPP and FPP are formed by the ERG20 protein. The different colors represent the different strategies applied for improved isoprenoid production. HMG-CoA—3-hydroxy-3-methylglutaryl coenzyme A, IPP—isopentenyl diphosphate, DMAPP—dimethylallyl diphosphate, GPP—geranyl diphosphate, FPP—farnesyl diphosphate, PDC—pyruvate decarboxylase, ADH1-5—alcohol dehydrogenase, ALD6—aldehyde dehydrogenase, ACS₁/ACS₂—acetyl-coA synthetase, ERG10—acetyl-CoA C-acetyltransferase, ERG13—3-hydroxy-3-methylglutaryl-CoA synthase, tHMGR—truncated 3-hydroxy-3-methylglutaryl-CoA reductase, ERG12—mevalonate kinase, ERG8—phosphomevalonate kinase, ERG19—mevalonate diphosphate decarboxylase, IDI1—isopentenyl diphosphate:dimethylallyl diphosphate isomerase, ERG20—farnesyl diphosphate synthetase, ERG20^WW—ERG20-F96W-N127W, Δerg20—ERG20 knock out, UPC2-1—sterol regulatory element binding protein.

Figure 2.

Biosynthetic pathway of cannabinoids in C. sativa. Highlighted enzymes have to be transferred into a heterologous host as S. cerevisiae exhibiting a mevalonate pathway.

Figure 3.

THCA metabolization products in humans. The C₁₁ position is the major attacked site, but C₈ position can be also hydroxylated (Grotenhermen 2003).