The present invention is directed to nucleic acid sequences of Ginkgo biloba diterpene synthases, particularly of a levopimaradiene synthase. More specifically, the invention is directed to a cell of a unicellular organism, such as Saccharomyces cerevisiae or Escherichia coli, comprising levopimaradiene synthase for the metabolically engineered in vivo biosynthesis of a diterpene and a ginkgolide.