Biosynthesis of methyl-proline containing griselimycins, natural products with anti-tuberculosis activity.
Lukat, P., Katsuyama, Y., Wenzel, S., Binz, T., Konig, C., Blankenfeldt, W., Bronstrup, M., Muller, R.(2017) Chem Sci 8: 7521-7527
- PubMed: 29163906 
- DOI: https://doi.org/10.1039/c7sc02622f
- Primary Citation of Related Structures:  
5NCH, 5NCI, 5NCJ - PubMed Abstract: 
Griselimycins (GMs) are depsidecapeptides with superb anti-tuberculosis activity. They contain up to three (2 S ,4 R )-4-methyl-prolines (4-MePro), of which one blocks oxidative degradation and increases metabolic stability in animal models. The natural congener with this substitution is only a minor component in fermentation cultures. We showed that this product can be significantly increased by feeding the reaction with 4-MePro and we investigated the molecular basis of 4-MePro biosynthesis and incorporation. We identified the GM biosynthetic gene cluster as encoding a nonribosomal peptide synthetase and a sub-operon for 4-MePro formation. Using heterologous expression, gene inactivation, and in vitro experiments, we showed that 4-MePro is generated by leucine hydroxylation, oxidation to an aldehyde, and ring closure with subsequent reduction. The crystal structures of the leucine hydroxylase GriE have been determined in complex with substrates and products, providing insight into the stereospecificity of the reaction.
Organizational Affiliation: 
Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) , Helmholtz Center for Infection Research and Pharmaceutical Biotechnology , Saarland University Campus , Building C2.3 , 66123 Saarbr¨¹cken , Germany . Email: Rolf.Mueller@helmholtz-hzi.de.