Identification of the Natural Product Rotihibin A as a TOR Kinase Signaling Inhibitor by Unbiased Transcriptional Profiling

Abstract

Bioactive natural products are important starting points for developing chemical tools for biological research. For elucidating their bioactivity profile, biological systems with concise complexity such as cell culture systems are frequently used, whereas unbiased investigations in more complex multicellular systems are only rarely explored. Here, we demonstrate with the natural product Rotihibin A and the plant research model system Arabidopsis thaliana that unbiased transcriptional profiling enables a rapid, label-free, and compound economic evaluation of a natural product's bioactivity profile in a complex multicellular organism. To this end, we established a chemical synthesis of Rotihibin A as well as that of structural analogues, followed by transcriptional profiling-guided identification and validation of Rotihibin A as a TOR signaling inhibitor (TOR=target of rapamycin). These findings illustrate that a combined approach of transcriptional profiling and natural product research may represent a technically simple approach to streamline the development of chemical tools from natural products even for biologically complex multicellular biological systems.

Identification of Novel Rotihibin Analogues in Streptomyces scabies , Including Discovery of Its Biosynthetic Gene Cluster

“…2B ). Previously, Halder et al established a chemical synthesis pathway of rotihibin A and structural analogues ( 26 ). In their structural analogue RotA-D3, the serine residue at position 2 of the amino acid chain was replaced by alanine.…”

“…In their structural analogue RotA-D3, the serine residue at position 2 of the amino acid chain was replaced by alanine. This derivative turned out to be more active than rotihibin A, as shown by the overall more pronounced plant growth retardation in an A. thaliana bioassay ( 26 ). Interestingly, our data suggest that S. scabies RL-34 would produce a natural rotihibin variant that is modified at the same position.…”

“…Recently, Halder et al chemically synthesized rotihibin A and a number of variants ( 26 ). They provide evidence that rotihibin A targets the TOR (target of rapamycin) kinase (TORK) pathway, which explains the observed effects on plants.…”

“…A culture filtrate containing rotihibins A and B inhibits the growth of lettuce seedlings, while purified rotihibin A causes shoot stunting in tobacco seedlings at low concentrations ( 25 ). Recently, it was demonstrated that rotihibin A acts as a TOR (target of rapamycin) kinase (TORK) pathway inhibitor ( 26 ). Therefore, we assessed the plant growth-inhibitory effect of the newly isolated compounds, designated rotihibins C and D, and found a severe effect on growth and photosystem II photochemistry efficiency in Lemna minor L. and Arabidopsis thaliana L. Heynh.…”

Structural diversity, biosynthesis, and biological functions of lipopeptides fromStreptomyces

“…197 Mechanistic investigations using Arabidopsis thaliana revealed that rotihibin A is an inhibitor of the target of rapamycin (TOR) signaling. 198 Recently, two novel rotihibins C and D, possessing a Thr3 rather than Ser3, were isolated from S. scabies RL-34 and 87-22. These also showed inhibiting activity on plant growth and effects on photosystem II.…”