CRYSTALLIZATION AND PRELIMINARY-X-RAY CRYSTALLOGRAPHIC STUDIES OF NONHISTONE REGION OF MACROH2A.1

Histone macroH2A has a novel hybrid structure consisting of a large no nhistone region and a region that closely resembles a full-length hist one H2A. One key to understanding macroH2A function is determining the structure and function of its nonhistone region. The nonhistone regio n of one of the two known macroH2A subtypes was expressed in Escherich ia coli and purified using affinity and molecular sieve chromatography , Crystals of the protein suitable for structural studies were grown f rom polyethylene glycol solutions by vapor equilibration techniques. T he crystals belong to the hexagonal space group P6(4) (or its enantiom orph P6(2)) with unit cell parameters: a = b = 106.2 Angstrom, c = 125 .9 Angstrom alpha = beta = 90 degrees, and gamma = 120 degrees. There are four molecules in the asymmetric unit. Self-rotation function stud ies revealed three twofold noncrystallographic rotation axes related a pproximately by 222 symmetry. These crystals have 47% solvent content and diffract to 3.8 Angstrom resolution. (C) 1995 Wiley-Liss, Inc.