We use a hybrid approach to study the structure and function of multi-protein complexes. A major focus of the lab is on complexes involved in the regulation of mRNA polyadenylation and deadenylation. Eukaryotic genes are normally transcribed as pre-mRNAs that must be processed before they are exported from the nucleus and translated into proteins. The 3´-end of the pre-mRNA is cleaved and a poly(A) tail is added to the new 3´-end. Several protein factors are required to co-ordinate the 3´-end processing reactions, and to facilitate communication with the transcription and splicing machinery. In yeast this includes a large multi-protein complex called Cleavage and Polyadenylation Factor (CPF). The poly(A) tail is required for export of the mRNA into the cytoplasm. It also enhances mRNA stability and stimulates translation, and its length can be regulated to influence these functions. For example, shortening of the poly(A) tail can decrease the efficiency of translation to control gene expression, and is the first step in mRNA turnover. The major deadenylase activities are found within the evolutionarily conserved, 1MDa Ccr4-Not complex and Pan2-Pan3. By understanding the structure and mechanisms of these protein complexes, we will gain insight into the regulation of mRNA polyadenylation and gene expression.

A second focus of the lab is the Fanconi anaemia (FA) core complex. This multi-subunit E3 ubiquitin ligase acts in a pathway that repairs DNA damage caused by DNA crosslinks. Mutation of the genes encoding subunits of the FA core complex results in Fanconi anaemia which includes developmental abnormalities, bone marrow failure and cancer predisposition. We are studying the complex using biochemical reconstitution and structural biology to understand the molecular basis for its function.