Enzymatic assembly of the salinosporamide γ-lactam-β-lactone anticancer warhead.
Katherine D BaumanVikram V ShendePercival Yang-Ting ChenDaniela Barretto Barbosa TrivellaTobias A M GulderSreekumar VellalathDaniel RomoBradley S MoorePublished in: Nature chemical biology (2022)
The marine microbial natural product salinosporamide A (marizomib) is a potent proteasome inhibitor currently in clinical trials for the treatment of brain cancer. Salinosporamide A is characterized by a complex and densely functionalized γ-lactam-β-lactone bicyclic warhead, the assembly of which has long remained a biosynthetic mystery. Here, we report an enzymatic route to the salinosporamide core catalyzed by a standalone ketosynthase (KS), SalC. Chemoenzymatic synthesis of carrier protein-tethered substrates, as well as intact proteomics, allowed us to probe the reactivity of SalC and understand its role as an intramolecular aldolase/β-lactone synthase with roles in both transacylation and bond-forming reactions. Additionally, we present the 2.85-Å SalC crystal structure that, combined with site-directed mutagenesis, allowed us to propose a bicyclization reaction mechanism. This work challenges our current understanding of the role of KS enzymes and establishes a basis for future efforts toward streamlined production of a clinically relevant chemotherapeutic.
Keyphrases
- crystal structure
- clinical trial
- hydrogen peroxide
- quantum dots
- papillary thyroid
- mass spectrometry
- crispr cas
- gram negative
- squamous cell
- current status
- quality improvement
- squamous cell carcinoma
- living cells
- protein protein
- binding protein
- small molecule
- childhood cancer
- young adults
- subarachnoid hemorrhage
- single molecule
- study protocol