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Andrew Flaus (NUI Galway, Galway, Ireland)Proteins are not static structures but undergo constant motion. Certain features of this dynamic capability facilitate function even in structural proteins. The nucleosome provides the universal packaging for eukaryotic genomes, involving the wrapping of 147 bp of DNA around a histone protein octamer to create the fundamental subunit of chromatin. Although the static structure of the nucleosome has been determined at better than 2√Ö resolution, the dynamic mechanisms which enable transparent access to wrapped DNA are not understood. This dynamics is a fundamental requirement of all genomic processes including transcription, replication and DNA repair. We are undertaking a comprehensive biochemical characterisation of the role of each residue in the histone octamer structure by alanine scanning mutagenesis with multiple readouts for structural stability and dynamics. To facilitate data interpretation, we are working to develop ways to map our assay readouts onto the nucleosome structure through visualisations of contact surfaces and inter-atomic interactions. This will allow us to uncover the cooperative interaction networks responsible for defining the dynamic capability