Fatty Acid Hydroxylase of the Fungus Fusarium oxysporum Is Possibly a Fused Protein of Cytochrome P450 and Its Reductase

Abstract Fatty acid subterminal (ω-1∼ω-3) hydroxylase of the fungus Fusarium oxysporum was solubilized from the microsomal fraction and partially purified. The hydroxylase activity was recovered into a single active fraction, and its spectral nature showed the presence of cytochrome P-450 (P-450). Fatty acid hydroxylase activity was markedly restored upon addition of FAD, FMN, and/or hemine to the eluted fraction. The fraction also exhibited other properties characteristic of both a hemeprotein and a flavin-containing reductase. These results are highly indicative that the fungal hydroxylase is a fused protein containing both P-450 and its reductase domains. In this aspect the fungal enzyme resembles bacterial P-450 BM3 , although it is membrane-bound unlike the bacterial counterpart.