7RON
Crystal structure of the Friedel-Crafts alkylating enzyme CylK from Cylindospermum licheniforme
Summary for 7RON
| Entry DOI | 10.2210/pdb7ron/pdb |
| Descriptor | CylK, 1,2-ETHANEDIOL, CALCIUM ION, ... (6 entities in total) |
| Functional Keywords | beta-propeller, beta-roll, calcium-dependent, alkylation, cylindrocyclophane, transferase |
| Biological source | Cylindrospermum licheniforme UTEX B 2014 |
| Total number of polymer chains | 1 |
| Total formula weight | 75905.72 |
| Authors | Ruskoski, T.B.,Boal, A.K. (deposition date: 2021-07-31, release date: 2022-03-23, Last modification date: 2024-05-22) |
| Primary citation | Braffman, N.R.,Ruskoski, T.B.,Davis, K.M.,Glasser, N.R.,Johnson, C.,Okafor, C.D.,Boal, A.K.,Balskus, E.P. Structural basis for an unprecedented enzymatic alkylation in cylindrocyclophane biosynthesis. Elife, 11:-, 2022 Cited by PubMed Abstract: The cyanobacterial enzyme CylK assembles the cylindrocyclophane natural products by performing two unusual alkylation reactions, forming new carbon-carbon bonds between aromatic rings and secondary alkyl halide substrates. This transformation is unprecedented in biology, and the structure and mechanism of CylK are unknown. Here, we report X-ray crystal structures of CylK, revealing a distinctive fusion of a Ca-binding domain and a β-propeller fold. We use a mutagenic screening approach to locate CylK's active site at its domain interface, identifying two residues, Arg105 and Tyr473, that are required for catalysis. Anomalous diffraction datasets collected with bound bromide ions, a product analog, suggest that these residues interact with the alkyl halide electrophile. Additional mutagenesis and molecular dynamics simulations implicate Asp440 in activating the nucleophilic aromatic ring. Bioinformatic analysis of CylK homologs from other cyanobacteria establishes that they conserve these key catalytic amino acids, but they are likely associated with divergent reactivity and altered secondary metabolism. By gaining a molecular understanding of this unusual biosynthetic transformation, this work fills a gap in our understanding of how alkyl halides are activated and used by enzymes as biosynthetic intermediates, informing enzyme engineering, catalyst design, and natural product discovery. PubMed: 35212625DOI: 10.7554/eLife.75761 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.68 Å) |
Structure validation
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