ENIGMA: Evolution of Nanomachines In Geospheres and Microbial Ancestors. This NAI team will explore catalysis of electron transfer reactions by prebiotic peptides to microbial ancestral enzymes to modern nanomachines, integrated over four and a half billion years of Earth’s changing geosphere. Theme 1 focuses on the synthesis and function of the earliest peptides capable of moving electrons on Earth and other planetary bodies. Theme 2 focuses on the evolutionary history of “motifs” in extant protein structures. Theme 3 focuses on how proteins and the geosphere co-evolved through geologic time.


Life on Earth is electric. The electronic circuitry is catalyzed by a small subset of proteins that function as sophisticated nanomachines. Currently, very little is known about the origin of these proteins on Earth or their evolution in early microbial life. To fill this knowledge gap, the ENIGMA research team proposes to conduct integrated and coordinated experimental, bioinformatic, and data-driven studies to explore the origin of catalysis, the evolution of protein structures in microbial ancestors, and the co-evolution of proteins and the geosphere. ENIGMA has three integrated research themes focused on understanding the evolution of proteins involved in electron transfer and energy generation:

The proposed team is dedicated to understanding how nature formed catalysts that serve as the pervasive nanomachines of life on Earth, and how analogous processes may have evolved on other planetary bodies within or beyond our solar system. The results of our research will advance our knowledge of how biochemistry emerged from geochemistry—specifically, the enzymatic functions of metal-bearing proteins emerged approximately 4 billion years ago from a geochemical and mineralogical milieu that in some respects mimicked the emergent biochemistry. This concept is of significance to the astrobiology context of all NASA missions, as we attempt to characterize critical features of near-surface environments in which life might emerge. Ultimately, our goal is for the proposed effort to inform future NASA missions about detection of life on planetary bodies in habitable zones. Our effort provides a unique window to potential planetary-scale chemical characteristics that might arise from abiotic chemistry, which must be understood if we are to recognize unique biosignatures on other worlds.