Nogalonic acid methyl ester cyclase (SnoaL) (SnoaL)

Nogalonic acid methyl ester cyclase, commonly known as SnoaL, is a small bacterial enzyme from Streptomyces nogalater that is essential for the biosynthesis of the anthracycline antibiotic nogalamycin [1, 2, 5]. It belongs to a family of polyketide cyclases that catalyze the final ring-closure step of the polyketide aglycone precursor through an intramolecular aldol condensation [1, 3]. SnoaL is distinguished by its unique catalytic mechanism, which employs an invariant aspartate residue (Asp121) as an acid/base catalyst to stabilize the enol(ate) intermediate without the use of a Schiff base or metal ion cofactors [1, 4]. Structurally, the enzyme adopts a distorted alpha+beta barrel fold, a motif that has since been identified in a wide variety of SnoaL-like proteins across different species, including those involved in the production of other clinically significant antineoplastics like doxorubicin and daunorubicin [1, 8, 32]. While SnoaL is not a direct therapeutic target for human diseases, it is a key target for metabolic engineering and synthetic biology efforts aimed at producing novel or improved polyketide-based drugs [5, 22, 35]. Its role in dictating the C-9 stereochemistry of the anthracycline core makes it a critical tool for the biocatalytic synthesis of complex natural products [5, 28].

Other names

SnoaLPolyketide cyclase SnoaLNogalonic acid methyl ester cyclaseotaY

No drugs are currently known to target this enzyme for therapeutic purposes; however, it catalyzes the intramolecular aldol condensation of polyketide precursors in antibiotic biosynthesis.