Conformational change and membrane association of the PutA protein are coincident with reduction of its FAD cofactor by proline.

The PutA protein is both the put repressor and a membrane-bound enzyme with proline and delta 1-pyrroline-5-carboxylate dehydrogenase activities. The conditions required for association of purified PutA protein with membrane vesicles suggested that a redox switching mechanism might determine the proportion of PutA protein functioning as a dehydrogenase (Wood, J. M. (1987) Proc. Natl. Acad. Sci. USA 84, 373-377). The FAD cofactor was released …