Temperature Responsive Control of Splicing by RNA Methylation

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

There is no mechanism to explain how the precise measurement of temperature could be linked to splicing decisions. This hinders our ability to understand how plants respond to temperature and also prevents us from using this versatile system to engineer artificial temperature-responsive splicing events, for synthetic biology and agriculture. Using a mutant screen and nanopore direct RNA sequencing, we discovered that the m6A RNA methyltransferase, FIO1, confers the property of temperature-responsiveness onto multiple splice events, some of which are already known to respond to temperature changes. The human orthologue of FIO1 is METTL16, which binds RNA stem-loop structures to control splicing and methylates noncoding RNAs, including U6snRNA. m6A base modifications alter RNA base-pair formation in context-dependent ways. Together, these findings suggest that plants utilise RNA methylation and thermosensitive RNA-RNA interactions, via a novel type of RNA thermometer, to control splicing.
We seek to understand how FIO1 recognises its target RNAs, how it modifies them and how this is linked to RNA processing. We will use state-of the-art methods to map the exact binding sites for FIO1 in nuclear RNA across a range of physiologically relevant temperatures and to probe the secondary structure of nuclear RNAs in the same conditions. We will use nanopore direct RNA sequencing to discover the sites of FIO1-dependent m6A modification and the FIO1-dependent splicing events, at the same temperatures. Through in vitro RNA binding experiments, with purified recombinant FIO1, and in vivo assays, by mutating temperature-responsive introns, we will determine the mechanism by which m6A, temperature and RNA structure interact. By making the corresponding mutations on MAF2 transgenes we will link the mechanism to the biology of flowering time control. We will test our models by engineering artificial biological "thermostats" to express transgenes in specific temperature ranges.