The expression of the Arabidopsis cytochrome P450 CYP82C4 is dependent on iron availability and the circadian rhythm and it correlates with genes involved in the early iron-deficiency response

Cytochrome P450 superfamily (CYP) is a large and diverse group of heme proteins able to catalyse the oxidation of organic substances by reducing oxygen to water (using NADH or NADPH). CYP proteins are object of particular interest for chemical and pharmaceutical companies, due to their potential to overcome the constraints of chemical synthesis. In plants, CYP82 family lacks orthologs in rice genome and might be a family evolved only in dicots. CYP82E4 from tobacco is a nicotine N-demethylase, that is responsible for conversion of nicotine to nornicotine and 8-methoxypsoralen is a substrate for CYP82C4; however the in vivo functions of Arabidopsis CYP82 family members are currently unknown. CYP82C4 (At4g31940) was identified as one of the genes highly expressed in Fe-deficient Arabidopsis thaliana roots, together with 2 other CYP genes, i.e. CYP82C3 (At4g31950) and CYP71B5 (At3g53280). By performing expression correlation analysis we show that, differently from CYP82C3 and CYP71B5, CYP82C4 is specifically correlated with genes involved in metal uptake and transport. Moreover, CYP82C4 promoter region possesses both IDE1-like and RY sequences, supporting CYP82C4 specific involvement in the Fe-deficiency response. While confirming that the CYP82C4 transcript accumulates in Fe-deficient Arabidopsis seedlings, with circadian fluctuations in a light–dependent way, we also demonstrate that such accumulation is suppressed under Fe excess. Full suppression of CYP82C4 expression, as observed in the atc82c4-1 KO mutant, is associated with longer roots at seedlings stage. We propose that CYP82C4 is involved in the early Fe deficiency response, possibly through an IDE1-like mediated pathway.