Biochemical analysis of chromatin structure and function using Drosophila embryo extracts

The biochemical analysis of chromatin structure and function is greatly facilitated by the availability of cell-free systems that assemble chromatin under physiological conditions. One such system that has shown great potential is derived from extracts of early Drosophila embryos. These embryos contain large maternal stocks of chromatin constituents, such as histones and assembly factors. Chromatin assembled in these extracts resembles native chromatin in many respects: it displays physiological nucleosome repeat lengths, it is complex, containing a wealth of nonhistone proteins as well as enzymatic activities, and it has dynamic properties that allow the interaction of DNA-binding proteins that regulate important cellular processes. Most importantly, chromatin with variant properties, e.g., with respect to the basic geometry of the nucleosomal array, histone modifications, and its content of linker histones or nonhistone proteins, can be obtained by manipulating the reconstitution conditions. The synthesis of uniform chromatin with specific characteristics should allow the analysis of the functional significance of the structural and biochemical heterogeneity observed in vivo. (C) 1997 Academic Press.