Crystallization and preliminary X-ray analysis of the ligand-binding domain of cAMP receptor protein.

The cyclic AMP receptor protein (CRP) from Escherichia coli regulates the expression of a large number of genes. In this work, CRP has been overexpressed, purified and digested by subtilisin and chymotrypsin. The fragments S-CRP (digested by subtilisin) and CH-CRP (digested by chymotrypsin) have been purified and crystallized. Crystals of S-CRP diffracted to 2.0 A resolution and belonged to space group P2(1), with unit-cell parameters a = 59.7, b = 75.1, c = 128.3 A, beta = 91.5 degrees . Crystals of CH-CRP diffracted to 2.8 A resolution and belonged to space group P222, with unit-cell parameters a = 45.8, b = 60.9, c = 205.6 A.