COCRYSTALLIZATION OF AN ETS DOMAIN (PU.1) IN COMPLEX WITH DNA - ENGINEERING THE LENGTH OF BOTH PROTEIN AND OLIGONUCLEOTIDE

The PU.1 transcription factor is a member of the ets gene family of re gulatory proteins, These molecules play a role in normal development a nd also have been implicated in malignant processes such as the develo pment of erythroid leukemia, The Ets proteins share a conserved DNA-bi nding domain (the ETS domain) that recognizes a purine-rich sequence w ith the core sequence: 5'-C/AGGAA/T-3'. This domain binds to DNA as a monomer, unlike many other DNA-binding proteins, The ETS domain of the PU.1 transcription factor has been crystallized in complex with a 16- base pair oligonucleotide that contains the recognition sequence. The crystals formed in the space group C2 with a = 89.1, b = 101.9, c = 55 .6 Angstrom, and beta = 111.2 degrees and diffract to at least 2.3 Ang strom, There are two complexes in the asymmetric unit, Production of l arge usable crystals was dependent on the length of both protein and D NA components, the use of oligonucleotides with unpaired A and T bases at the termini, and the presence of polyethylene glycol and zinc acet ate in the crystallization solutions, This is the first ETS domain to be crystallized, and the strategy used to crystallize this complex may be useful for other members of the ets family.