Thermomyces dupontii P450S and P450L Transcriptome

We found that a dominant thermophilic fungal Thermomyces, closely relative to Aspergillus species, had two P450 paralogs (P450S and P450L) in the gene cluster responsible for an important family of iron chelator precursors, prenylated indole alkaloids (PIAs). Among them, P450L was a unique fusion gene assigned as one protein containing one CYP like domain and one FAD-binding domain gene. Both two P450 genes have distinct multiple functions in the biosynthesis of PIAs and their corresponding iron chelators, which plays an important role in fungal adaption to temperature changes. P450S is involved in the formation of the complex pyranoindole rings and further two iron chelatoring hydroxamate cores derived from the diketopiperazine in PIAs. P450L is responsible for introducing a double bond between the complex pyranoindole ring and the diketopiperazine in PIAs, thus forming a spectacular conjugating unsaturated system. Remarkably, both P450S and P450L contributed to the formation of the third iron chelating hydroxamate core in the rearranged PIAs. Disruption of the P450S gene resulted in undivided lipid droplets and abnormal mitochondria while disruption of the P450L gene led to deformed vacuoles. Transcriptomics analysis revealed that iron-dependent proteins including ROS-induced cysteine dioxygenase (CDO) gene, were most extremely down-regulated in two mutants P450S and P450L. Further experiment indicated that the levels of iron and ROS were both strongly decreased, which might explain the decreased conidial germination rate. Thus, our results indicated a P450 iron low temperature relationship, which provided mechanistic insights into the functions of most common P450 genes and other iron related genes such as CDO genes in fungal adaption to temperature changes.