An aminotransferase from bacterium ATCC 55552 deaminates hydrolyzed fumonisin B1

Previous research identified several microorganisms and pathways capable of degrading the mycotoxin fumonisin B1 (FB1). Degradation of FB1 by microorganisms seems to comprise two essential steps: hydrolysis to hydrolyzed fumonisin B1 (HFB1) and deamination of the hydrolysis product. One of the previously studied microorganisms was the Gram negative bacterium ATCC 55552. The gene corresponding to the first step of FB1 degradation in this bacterium was identified, but the genetic basis for deamination of the hydrolyzed intermediate remained unexplained (Duvick et al. 2000, PCT patent application WO200004158). Here we report the sequence and HFB1-deaminating activity of a novel aminotransferase encoded by the bacterium ATCC 55552. The corresponding gene was identified, sequenced, and over-expressed in Escherichia coli. Cell lysates of the recombinant E. coli strain showed distinct HFB1-deaminating activity in the presence of pyridoxal phosphate and pyruvate, as was demonstrated by liquid chromatography–mass spectrometry. Thus, we suggest the novel enzyme to be part of the fumonisin catabolic pathway of the bacterium ATCC 55552.