Mechanisms of ATP-dependent chromatin remodeling motors

Two different classes of molecular machines catalyze the conformational changes that define open vs. closed chromatin domains: the SWI/SNF complex generates a distribution of nucleosomal states, which contain nucleosomes with altered positions, altered composition and altered DNA paths. These enable efficient exposure of short regions of DNA for localized binding of activators or repressors. The ACF complex only generates chromatin with regularly spaced nucleosomes, which enables long-range folding of chromatin into silent chromatin. The study of SWI/SNF and ACF complexes had raised several intriguing questions: (i) how does the single active site in SWI/SNF complexes generate several different types of remodeled products? (ii) how does ACF generate evenly spaced nucleosomes and; (iii) why do SWI/SNF and ACF generate such different products despite having highly homologous motor domains? In my technical talk I will described our progress on addressing these questions.