BCL6 ENCODES A SEQUENCE-SPECIFIC DNA-BINDING PROTEIN

Chromosomal rearrangements of BCL6 are commonly associated with diffus e large-cell lymphomas. We set out to determine the DNA-binding site o f a glutathione-S-transferase fusion protein containing the BCL6 zinc finger region by employing cyclic amplification and selection of targe ts (CASTing), From oligonucleotides containing 16 central random bases , sequences binding to the protein on glutathione-coated beads were re peatedly selected and amplified by polymerase chain reaction (PCR), Th e binding sites were cloned and sequenced. A consensus, TTTNNNGNNATNCT TT, was obtained. Protein binding studies of double-stranded oligomers containing point mutations within the 3' CTTT confirmed the binding s pecificity of this part of the consensus. In addition, evidence indica ted that some of the base pairs held constant in the oligonucleotides used for CASTing also contributed to binding. (C) 1995 Wiley-Liss, Inc .