Ribonucleic acid (RNA) is exceedingly sensitive to degradation compared to DNA. The current protocol for storage of purified RNA requires freezing conditions below −20 °C. Recent advancements in biological chemistry have identified amino acid-based ionic liquids as suitable preservation media for RNA, even in the presence of degrading enzymes. However, the mechanistic insight into the interaction between ILs and RNA is unclear. To the best of our knowledge, no attempts are made so far to provide a molecular view. This work aims to establish a detailed understanding of how ILs enable structural stability to RNA sourced from Torula yeast. Herein, we manifest the hypothesis of multimodal binding of IL and its minimal perturbation to the macromolecular structure, with several spectroscopic techniques such as time-resolved fluorescence and fluorescence correlation spectroscopy (FCS) aided with molecular dynamics at microsecond time scales. Relevant structural and thermodynamic details from biophysical experiments confirm that even long-term RNA preservation with ILs is a possible alternative devoid of any structural deformation. These results establish a unifying mechanism of how ILs are maintaining conformational integrity and thermal stability. The atomistic insights are transferable for their potential applications in drug delivery and biomaterials by considering the advantages of having maximum structural retention and minimum toxicity.

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Lanthipeptides are ribosomally-synthesized natural products from bacteria featuring stable thioether-crosslinks and various bioactivities. Herein, we report on a new clade of tricyclic class-IV lanthipeptides with curvocidin from Thermomonospora curvata as its first representative. We obtained crystal structures of the corresponding lanthipeptide synthetase CuvL that showed a circular arrangement of its kinase, lyase and cyclase domains, forming a central reaction chamber for the iterative substrate processing involving nine catalytic steps. The combination of experimental data and artificial intelligence-based structural models identified the N-terminal subdomain of the kinase domain as the primary site of substrate recruitment. The ribosomal precursor peptide of curvocidin employs an amphipathic α-helix in its leader region as an anchor to CuvL, while its substrate core shuttles within the central reaction chamber. Our study thus reveals general principles of domain organization and substrate recruitment of class-IV and class-III lanthipeptide synthetases.

Lanthipeptides are ribosomally‐synthesized natural products from bacteria featuring stable thioether‐crosslinks and various bioactivities. Herein, we report on a new clade of tricyclic class‐IV lanthipeptides with curvocidin from Thermomonospora curvata as its first representative. We obtained crystal structures of the corresponding lanthipeptide synthetase CuvL that showed a circular arrangement of its kinase, lyase and cyclase domains, forming a central reaction chamber for the iterative substrate processing involving nine catalytic steps. The combination of experimental data and artificial intelligence‐based structural models identified the N‐terminal subdomain of the kinase domain as the primary site of substrate recruitment. The ribosomal precursor peptide of curvocidin employs an amphipathic α‐helix in its leader region as an anchor to CuvL, while its substrate core shuttles within the central reaction chamber. Our study thus reveals general principles of domain organization and substrate recruitment of class‐IV and class‐III lanthipeptide synthetases.