Abstract
Terpenes are the largest class of natural products with extensive structural diversity and are widely used as pharmaceuticals, herbicides, flavourings, fragrances, and biofuels. While they have mostly been isolated from plants and fungi, the availability and analysis of bacterial genome sequence data indicates that bacteria also possess many putative terpene synthase genes. In this study, we further explore this potential for terpene synthase activity in bacteria. Twenty two potential class I terpene synthase genes (TSs) were selected to represent the full sequence diversity of bacterial synthase candidates and recombinantly expressed in E. coli. Terpene synthase activity was detected for 15 of these enzymes, and included mono-, sesqui- and diterpene synthase activities. A number of confirmed sesquiterpene synthases also exhibited promiscuous monoterpene synthase activity, suggesting that bacteria are potentially a richer source of monoterpene synthase activity then previously assumed. Several terpenoid products not previously detected in bacteria were identified, including aromandendrene, acora-3,7(14)-diene and longiborneol. Overall, we have identified promiscuous terpene synthases in bacteria and demonstrated that terpene synthases with substrate promiscuity are widely distributed in nature, forming a rich resource for engineering terpene biosynthetic pathways for biotechnology.
Highlights
Terpenoids, or isoprenoids, are a large class of structurally diverse natural products, with more than 80,000 compounds described in the Dictionary of Natural Compounds
Terpene synthases (TSs) from different origins show substantial differences in overall primary amino acid sequence, but possess a strongly conserved metal binding domain consisting of an acidic amino acid (AA)-rich motif (D/N) DXX (D/E) or DDXXXE located within 80–120 or 230–270 AA of the N-terminus and an Asn/Ser/Glu triad closer to the C-terminus, which are the signature domains of the class I TS. 2,167 protein sequences out of 73,714 proteins were identified to be TSs and their homologues based on the Hidden Markov Model (HMM) search as described in the Material and Methods
Presumptive TS homologue protein sequences were clustered by pairwise similarity, and from the resulting neighbour-joining tree (Fig 1) we identified TSs from Gram-positive bacteria, mainly from the order Actinomycetales, as well as Gram-negative bacteria belonging to numerous orders
Summary
Terpenoids, or isoprenoids, are a large class of structurally diverse natural products, with more than 80,000 compounds described in the Dictionary of Natural Compounds (http://dnp. chemnetbase.com). The products obtained by in vitro assay with purified TSs upon incubation with GPP and FPP or in vivo cultivation in E. coli are listed.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
