DEPENDENCE OF STEROID TRANSFORMATION PATHWAY IN AGROBACTERIUM-TUMEFACIENS ON INTRACELLULAR NAD(P)H LEVEL

A correlation between the intracellular NAD(P)H level and the type of steroid transformation process (oxidation, reduction) in Agrobacterium tumefaciens was studied. At an intracellular NAD(P)H level of 250 con ventional units per mg dry biomass (U) hydrocortisone was oxidized by bacteria. An increase of NAD(P)H concentration to 400 U hindered the p rocess of hydrocortisone transformation, and at 600 U of NAD(P)H this reaction was completely abolished. At an NAD(P)H level of 250 U, bacte ria converted cortisone acetate to cortisone, and the latter was oxidi zed to prednisone, the ratio of concentrations of these products being 7 : 1. During the subsequent incubation this ratio shifted in favor o f prednisone, which was subjected to further degradation. When the pro cess of cortisone to prednisone oxidation was blocked [at NAD(P)H leve l of 400 - 600 U], bacteria decomposed the steroid ring. Accumulation of cortisone and prednisone at a 1 : 1 ratio was observed also over th e course of prednisone acetate transformation. This compound was reduc ed to cortisone and cortisone acetate, the ratio of these products bei ng 5 : 1 at an intracellular NAD(P)H level of 600 U. It is suggested t hat the pathway of steroid transformation (oxidation or reduction) is governed by the intracellular level of NAD(P)H.