The functional and adaptive roles of RNA recoding

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PROJECT SUMMARY Organisms use a variety of molecular mechanisms to adapt to their environments. RNA editing occurs widely across organisms and generates non-synonymous codon changes in mRNAs, thereby altering the amino acid sequence of proteins. In cephalopods and fungi, this ‘recoding’ generates incredible diversity in proteins across most cellular processes. However, the functions of RNA recoding in these organisms are largely unknown. How is RNA recoding used to support physiological needs and facilitate adaptation? The research proposed here investigates how cephalopod and fungal RNA recoding regulates the function of proteins involved in two core cellular processes: microtubule-based transport and DNA replication and repair. This work will illuminate how RNA recoding modulates protein function to support phenotypic plasticity and adaptation and will advance our understanding of the regulation and functions of highly conserved cellular machineries. In Aim 1, Dr. Rangan will investigate how RNA recoding diversifies the function of microtubule motor protein complexes. In the K99 phase, she will evaluate the effects of RNA recoding on dynein and kinesin motor complexes using in vivo cargo transport assays and single-molecule motility assays. She will also investigate how RNA recoding of motor proteins is coordinated at different temperatures in squid to facilitate transport. In Aim 2, Dr. Rangan will investigate how RNA recoding alters the function of DNA replication and repair proteins. In the K99 phase, she will characterize the effects of RNA recoding on DNA polymerases epsilon and zeta using assays for mutation rate, fidelity, and processivity. In the R00 phase, she will evaluate how temperature-dependent recoding of DNA polymerases alters function and extend this characterization to other proteins involved in DNA replication and repair. In Aim 3, Dr. Rangan will explore how RNA recoding of DNA replication machinery influences genomic mutation rate and bias in the filamentous fungus Neurospora crassa. In the K99 phase, she will use RNA-seq to evaluate temperature-dependent changes in RNA editing in Neurospora ascospores. During the R00 phase, she will perform mutation accumulation experiments with recoding site mutants and wild type fungi to elucidate the role of RNA recoding in mutagenesis. Dr. Rangan is committed to developing an independent research program centered around investigating how RNA editing in diverse organisms supports phenotypic plasticity and adaptation. To facilitate her transition to independence, she will attend diverse scientific conferences and participate in UCSD classes on topics of career development and lab management. She will receive guidance and support from her mentoring committee and her primary mentor, Sam Reck-Peterson. This development plan, combined with training in bioinformatics and computational genomics (with Ludmil Alexandrov, UC San Diego) as well as Neurospora biology and genetics (with Katherine Borkovich, UC Riverside) will prepare her for success in an independent career.