Block-replacement mutagenesis for functional dissection of multiple transcription factor complexes

We propose a simple method for investigation of roles of individual transcr iption factors in complexes of multiple factors bound to the same cis eleme nt. By block-replacement mutagenesis. the whole cis element is replaced wit h a new one containing a binding site for a single factor. From the reporte r activity of the mutant promoter construct. the importance of the individu al factor in transcriptional activation is deduced. This approach allowed u s to functionally identify SPI as the most important PR1 binding transcript ion factor in the MN promoter. (C) 2001 Elsevier Science B.V. All rights re served.