METABOLISM OF METHANESULFONIC-ACID INVOLVES A MULTICOMPONENT MONOOXYGENASE ENZYME

A novel methylotroph, strain M2, capable of utilizing methanesulfonic acid (MSA) as a sole source of carbon and energy was the subject of th ese investigations, The initial step in the biodegradative pathway of MSA in strain M2 involved an inducible NADH-specific monooxygenase enz yme (MSAMO). Partial purification of MSAMO from cell-free extracts by ion-exchange chromatography led to the loss of MSAMO activity. Activit y was restored by the mixing of three distinct protein fractions desig nated A, B and C. The reconstituted enzyme had a narrow substrate spec ificity relative to crude cell-free extracts. Addition of FAD and ferr ous ions to the reconstituted enzyme complex resulted in a fivefold in crease in enzyme activity, suggesting the loss of FAD and ferrous ion from the multicomponent enzyme on purification. Analysis of mutants of strain M2 defective in the metabolism of C-1 compounds indicated that methanol was not an intermediate in the degradative pathway of MSA an d also confirmed the involvement of a multicomponent enzyme in the deg radation of MSA by methylotroph strain M2.