STRUCTURAL AND FUNCTIONAL-ANALYSIS OF CHROMATIN ASSEMBLED FROM DEFINED HISTONES

In this review we describe how the extract-mediated chromatin assembly system derived from preblastoderm Drosophila embryos can be modified to assemble chromatin from defined histones. This approach combines th e advantages of assembling (i) chromatin templates from homogenous his tones with (ii) an assembly system that generates chromatin with physi ological nucleosome spacing and density and that contains the biologic al complexity of in vivo chromatin. We have used this technique to ass emble nonacetylated and hyperacetylated histones into chromatin (K. P. Nightingale, R. Wellinger, J. Sogo, and P. B. Becker, 1998, EMBO J. 1 7, 2865-2876; W. A. Krajewski and P. B. Becker, 1998, Proc. Natl. Acad . Sci. USA 95, 1540-1545), and use this as an example to detail the st ructural and transcriptional assays used to compare and characterize t hese chromatin templates. The application of this procedure to assembl e chromatin from recombinant histones should facilitate a wide variety of studies on the role(s) of histone mutants and variants. (C) 1998 A cademic Press.