Mechanistic investigation of the cross-talk between spliceosomal complexes and polyadenylation factors

Splicing and polyadenylation are two essential steps of gene expression that account, to a great extent, for the complexity of eukaryotes. The two processes are catalysed by the spliceosome and the polyadenylation apparatus – two macromolecular machines of megadalton-size which contain more than 70 and 20 proteins, respectively. The two machines associate physically to form composite assemblies, where cross-talk events support emerging layers of regulation of splicing and polyadenylation. These assemblies are primarily unexplored from a mechanistic perspective, due to their excessive size, complexity and dynamics. By employing state of the art technologies and our long-standing expertise in the structural biology of splicing, the time is now ripe for a thoroughgoing investigation of these assemblies. Thus, we aim to stall and isolate composite assemblies relevant for: (i) the coupling between splicing and polyadenylation, (ii) the definition of exons during constitutive and alternative splicing and (iii) protection of genes from premature polyadenylation. Afterwards, we will characterise their 3D structures and functions by electron cryo-microscopy and complementary biochemical methods. The proposed research is expected to be eye-opening and bring a substantive contribution to our understanding of how fundamental processes of gene expression integrate mechanistically.