Lukas Lauterbach

Spata-13,17-diene Synthase, an Enzyme with Sesqui-, Di- and Sesterterpene Synthase Activity from Streptomyces xinghaiensis

A terpene synthase from the marine bacterium Streptomyces xinghaiensis has been characterised, including a full structure elucidation of its products from various substrates and an in-depth investigation of the enzyme mechanism by isotope labelling experiments, metal cofactor variations, and mutation experiments. The results revealed an interesting dependency of Mn2+ catalysis on the presence of Asp-217, a residue that is occupied by a highly conserved Glu in most other bacterial terpene synthases.

Two Diterpene Synthases for Spiroalbatene and Cembrene A from Allokutzneria albata

Two bacterial diterpene synthases from the actinomycete Allokutzneria albata were investigated, resulting in the identification of the structurally unprecedented compound spiroalbatene from the first and cembrene A from the second enzyme. Both enzymes were thoroughly investigated in terms of their mechanisms by isotope labeling experiments, site-directed mutagenesis, and variation of the metal cofactors and pH value. For spiroalbatene synthase, the pH- and Mn2+ -dependent formation of the side product thunbergol was observed, which is biosynthetically linked to spiroalbatene.

Two Bacterial Diterpene Synthases from Allokutzneria albata Produce Bonnadiene, Phomopsene, and Allokutznerene

Two diterpene synthases from Allokutzneria albata were studied for their products, resulting in the identification of the new compound bonnadiene from the first enzyme. Although phylogenetically unrelated to fungal phomopsene synthase, the second enzyme produced a mixture of phomopsene and a biosynthetically linked new compound, allokutznerene, as well as spiroviolene. Both enzymes were subjected to in-depth mechanistic studies involving isotopic labelling experiments, metal-cofactor variation, and site-directed mutagenesis. Oxidation products of phomopsene and allokutznerene are also discussed.

Deciphering the genome and secondary metabolome of the plant pathogen Fusarium culmorum

Fusarium culmorum is one of the most important fungal plant pathogens that causes diseases on a wide diversity of cereal and non-cereal crops. We report herein for the first time the genome sequence of F. culmorum strain PV and its associated secondary metabolome that plays a role in the interaction with other microorganisms and contributes to its pathogenicity on plants. The genome revealed the presence of two terpene synthases, trichodiene and longiborneol synthase, which generate an array of volatile terpenes. Furthermore, we identified two gene clusters, deoxynivalenol and zearalenone, which encode for the production of mycotoxins. Linking the production of mycotoxins with in vitro bioassays, we found high virulence of F. culmorum PV on maize, barley and wheat. By using ultra-performance liquid chromatography-mass spectrometry, we confirmed several compounds important for the behaviour and lifestyle of F. culmorum. This research sets the basis for future studies in microbe-plant interactions.

Exploiting the Synthetic Potential of Sesquiterpene Cyclases for Generating Unnatural Terpenoids

The substrate flexibility of eight purified sesquiterpene cyclases was evaluated using six new heteroatom-modified farnesyl pyrophosphates, and the formation of six new heteroatom-modified macrocyclic and tricyclic sesquiterpenoids is described. GC-O analysis revealed that tricyclic tetrahydrofuran exhibits an ethereal, peppery, and camphor-like olfactoric scent.

A Clade II‐D Fungal Chimeric Diterpene Synthase from Colletotrichum gloeosporioides Produces Dolasta‐1(15),8‐diene

Based on a terpenoid overproduction platform in yeast for genome mining, a chimeric diterpene synthase from the endophytic fungus Colletotrichum gloeosporioides ES026 was characterized as the (5R,12R,14S)-dolasta-1(15),8-diene synthase. The absolute configuration was independently verified through the use of enantioselectively deuterated terpene precursors, which unequivocally established the predicted C1-III-IV cyclization mode for this first characterized clade II-D enzyme. Extensive isotopic labeling experiments and isolation of the intermediate (1R)-δ-araneosene supported the proposed cyclization mechanism.