CLAMP Protein Binding Microarray (PBM) experiment

To investigate the DNA binding specificity of the CLAMP protein, we have designed a custom PBM to interrogate the binding of CLAMP to DNA sequences extracted from the Drosophila melanogaster genome. Specific regions were extracted based on ChIP-seq data, motif occurence and proximity to gene transcription start sites. N-terminal GST-tagged protein samples were made for the C-terminal four and six zinc finger portions of the protein CLAMP; samples were made by in vitro transcription translation (IVT). IVT reaction mixtures for the two CLAMP constructs were applied directly to the PBM microarray and incubated for 1hour. Microarray-bound protein was fluorescently labeled using Alexa488-conjugated antibodies targeting GST, and the microarray was scanned in using a standard microarray scanner. Median fluorescence intensity over eight replicate probes was reported for each unique DNA sequence on the microarray.