Hoog, T. G.; Pawlak, M. R.; Gaut, N. J.; Baxter, G. C.; Bethel, T. A.; Adamala, K. P.; Engelhart, A. E.

Mars is a particularly attractive candidate among known astronomical objects to potentially host life. Results from space exploration missions have provided insights into Martian geochemistry indicating oxychlorine species, particularly perchlorate, are ubiquitous features of the Martian geochemical landscape. Perchlorate presents potential obstacles for known forms of life due to its toxicity. However, it can also provide potential benefits, such as producing brines by deliquescence, like those thought to exist on present-day Mars. Here we show perchlorate brines inactivate representative protein enzymes, while supporting folding and catalysis of functional RNAs. Additionally, we show perchlorate and other oxychlorine species enable new ribozyme functions, including regulatory behavior, copying of structured RNAs, and the first ribozyme-catalyzed chlorination of organic molecules. We suggest nucleic acids are uniquely well-suited to present-day hypersaline Martian environments. Furthermore, putative Martian near- or subsurface oxychlorine brines, and brines found in potential lifeforms, could provide a unique niche for biomolecular evolution.