Investigating the syntax of protein disorder in RNA-binding function

Context and challenge. Molecular interactions between proteins and RNA sustain life. RNA-binding proteins (RBPs) are enriched for intrinsically disordered regions (IDRs) which, unlike folded domains, exist in a dynamic ensemble of interconverting conformations. Despite the lack of stable structure, these IDRs are now recognised as key mediators of various types of protein-RNA activities, thereby dictating the cellular functions of RBPs. Yet, because of several challenges specific to flexible and disordered regions, the functional characterisation of IDRs has lagged. Hence, the big question of how the majority of RBPs selectively bind and regulate their RNA targets in the post-translation regulation of gene expression remains unanswered. Research aims and objectives. Elucidating the RNA-binding function of IDRs represents a major frontier in biology and our research proposal aims to tackle this challenge in a systematic manner. Our bottom-up investigations have enabled us to reveal new and diverse features by which IDRs contribute to the RNA-binding function of RBPs, that we propose to investigate towards a better understanding of IDR signatures and complexities. We aim to challenge tenets and some of the prevailing notions of IDRs by providing insights into the immense variety of interaction modes displayed by IDRs sequences and motifs, as well as the context-dependency of their structural disorder and functional behaviour. Through the investigation of evolutionarily linked model proteins, we propose to study these unorthodox interactions and expect to reveal new paradigms for protein-RNA biology. We will be integrating, adapting and/or developing methodologies and protocols to tackle our objectives and respond to the challenges posed by these systems. Potential applications and benefits. This research will contribute to a deeper understanding of the intrinsically disordered ‘dark’ portion of the human proteome and of fundamental molecular recognition processes that are critical for life. As RBPs interact with RNAs to carry out a myriad of essential functions of all cells and organisms, no area of biology is untouched by an understanding of the roles and modes of action of RBPs. Predicting RNA-binding preferences for RBPs based on computational analysis is not yet possible, and this is a considerably greater challenge for disordered and cryptic RNA-binding motifs. Our proposed study will therefore be highly relevant, timely and important for the wide and vibrant community of RNA biology scientists and beyond. Relevance to the BBSRC long-term research and innovation priorities. These aims align with the BBSRC long-term research and innovation priority of ‘Frontier bioscience: understanding the rules of life’.