Nanoarchitechture of cytochrome P450 system using a ring-shaped protein complex

Proliferating cell nuclear antigen (PCNA) from Sulfolobus solfataricus is a heterotrimeric ring-shaped protein. Bacterial cytochrome P450 (P450) that is one of promising biocatalysts requires electron transfer via two kinds of electron transfer proteins. Here we report that the fusion proteins of three subunits of PCNA and a bacterial P450 and its electron transfer proteins formed a quite stable heterotrimeric complex, and showed extremely high catalytic activities compared to the equimolar mixture of those. This complex formation utilizing PCNA could be valuable for nanoarchitecture of complicated multienzymatic reactions as well as applications of electron transport proteins.