Assembly and remodeling of nucleosomes

The nucleosome, the basic unit of chromatin organisation, is critical for a ll the functions of the genome (transcription, replication, repair and reco mbination). Thus, controling nucleosome dynamics will have a direct impact on each of these functions. The assembly and remodelling of the nucleosome has been intensely studied in recent years. This review outlines our curren t knowledge of the possible factors involved in these processes. Mostly ide ntified by fractionation of cellular or embryonic extracts, these factors d isplay overlapping properties in their molecular function. Their possible r edundancies, targeted functions and potential interconnections are discusse d. Genetic approaches in simple model systems (yeast and drosophila) have b egun to explore their physiological role. Furthermore, the recent identific ation of mutations in genes encoding for subunits of these factors in human diseases underlines their importance. Future challenges will be to better understand the processes that control their action at specific sites within the nucleus. This could reveal the exact functions of these factors in hig her organisms.