Contribution of cytochrome P450 to the diversification of eukaryotic organisms.

Emergence of eukaryotic cells in the ancient world of prokaryotic life was dependent on P450 as the synthesis of sterols, an essential constituent of the plasma membrane, required a P450-catalyzed reaction. As the ancestral monocellular eukaryotic organisms evolved into multicellular eukaryotes, and then diversified to plants, fungi, and animals with different body organizations and metabolic activities, many novel compounds were created in order to meet the requirements for increasing complex metabolic activities of a wide variety of eukaryotic organisms. Many new P450s, created by gene duplication and mutation, contributed to the synthesis of those novel compounds in animals, plants, and fungi, and supported the diversification of the eukaryotes. Many secondary metabolites of plants, which protect the plants from the predation by herbivorous animals, were also synthesized by P450-catalyzed reactions. The herbivorous animals detoxified the noxious foreign compounds in the plants by P450. This "chemical warfare" between animals and plants is particularly evident in plants-insects interaction, and contributed to the coevolution and diversification of both plants and insects. The interaction between flowering plants and insect pollinators, which contributed to their coevolution, also depends on various plant compounds synthesized by P450-catalyzed reactions. P450 has made highly important contributions to the evolution and diversification of eukaryotic organisms.