Steve Ealick's Research Group

Toxoflavin Lyase

PDB files:

*3PKV apoTflA

*3PKW holo TflA

*3PKX TflA complex with toxoflavin


Toxoflavin is an azapteridine that is toxic to various plants, fungi, animals, and bacteria.  This toxicity motivated the development of transgenic plants that degrade toxoflavin by expressing a gene tflA of Paenibacillus polymyxa JH. The metalloenzyme TflA, toxoflavin lyase, is structurally homologous to proteins of the vicinal oxygen chelate superfamily. 

TflA is an α/β protein formed from two domains each containing a seven-stranded mixed β-sheet. In turn each of the domains contain two modules. Within each domain, the modules are structurally similar to each other and are related by pseudotwofold symmetry.


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In the complex, toxoflavin interacts with residues from each of the four modules. The manganese binding site consists of a facial triad comprising residues His60, Glu113, and Glu138 (1-His-2-carboxylate). 

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*Fenwick MK, Philmus B, Begley TP, and Ealick SE. Toxoflavin Lyase Requires a Novel 1-His-2-Carboxylate Facial Triad. Biochemistry 50:1091-1100 (2011). Abstract. PubMed

Philmus B, Abdelwahed S, Williams HJ, Fenwick MK, Ealick SE, and Begley TP. Identification of the product of Toxoflavin lyase: degradation via a Baeyer-Villiger oxidation. J. Am. Chem. Soc. 134:5326-5330. (2012). Abstract PubMed

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