NSF-BSF: Deciphering the factors that govern the temperature-dependence of ADAR reactivity and dsRNA substrate recognition

RNA editing is a process found in many organisms, including humans, capable of intercepting genetic messages and changing the encoded information. This allows for a range of different proteins to be made from a single gene. The ability of different organisms to modulate the information content in RNA through editing is likely to have a substantial impact on how organisms’ respond to stresses they encounter (e.g. changes in temperature, exposure to harmful substances or pathogens, etc). This collaborative effort involving two labs in the U.S. and two labs in Israel will investigate RNA editing enzymes called ADARs (adenosine deaminases that act on RNA) from different organisms. These efforts will advance our understanding of how editing can be used by an organism to thrive in its unique environment. This project provides a unique opportunity for interdisciplinary training of students spanning molecular biology, nucleic acid chemistry, enzymology, and structural biology. Each lab will contribute a different disciplinary effort to achieve in-depth understanding of RNA editing by ADARs as a function of body temperature, which is critically important in a changing climate. The team will maximize the broader impact of the research discoveries by disseminating our results to interested communities including the RNA editing scientific community, graduate students, undergraduate students, K-12 students and the general public. The proposed new work is a joint NSF-BSF grant; it will be carried out by an American team directed by Professors Peter Beal and Andrew Fisher and an Israeli effort led by Professors Shay Ben-Aroya and Erez Levanon. The Ben-Aroya/Levanon team have established the baker’s yeast, S. cerevisiae, as a versatile screening platform to evaluate the editing activity of ADARs from different organisms. Using this platform, they identified bird ADARs as highly efficient adenosine-to-inosine (A to I) editors in yeast and have advanced the hypothesis that this is a consequence of the high body temperature of birds. In this project, all four labs will work together to define the critical features of bird ADARs that lead to the high editing activity and define its molecular basis. This will be accomplished using domain swapping and random mutagenesis coupled with additional screens for growth effects in yeast. Purified bird ADAR proteins will be subjected to RNA binding, deamination rate measurements and structural studies of ADAR-RNA complexes. Finally, ADARs from other organisms, that inhabit different environmental niches, will be characterized to define the generality of the observed phenomenon. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.