Mutagenesis studies on TenA: A thiamin salvage enzyme from Bacillus subtilis

TenA catalyzes the hydrolysis of 4-amino-5-aminomethyl-2-methylpyrimidine and participates in the salvage of base-degraded thiamin. Here, we describe mutagenesis of the active site of TenA guided by structures of the enzyme complexed to a substrate analog and to the product. Catalytic roles for each of the active site residues are identified and a mechanism for the reaction is described.