Effector component of the toluene-4-monooxygenase multicomponent enzyme system which catalyzes the O2- and NADH-dependent hydroxylation of toluene to form p-cresol (PubMed:1885512, PubMed:15240250, PubMed:11297417, PubMed:15882052, PubMed:19033467). Required for optimal efficiency and specificity of the holoenzyme (PubMed:15882052, PubMed:19033467). Xenobiotic degradation; toluene degradation. The alkene monooxygenase multicomponent enzyme system is composed of an electron transfer component and a monooxygenase component interacting with the effector protein TmoD. The electron transfer component is composed of a ferredoxin reductase (TmoF) and a ferredoxin (TmoC), and the monooxygenase component is formed by a heterohexamer (dimer of heterotrimers) of two alpha subunits (TmoA), two beta subunits (TmoE) and two gamma subunits (TmoB). Cells lacking this gene show a complete loss of toluene-4-monooxygenase activity. Belongs to the TmoD/XamoD family.