21] Induced structural changes in protein-DNA complexes

Abstract

Publisher Summary Transcription factors are known to induce the bending of regulatory gene DNA. The typical case is exemplified by the sharp bending of promoter DNA on binding to the E. coli cyclic AMP receptor protein (CAP). The bending is thought to be correlated with the activation of RNA polymerase. The λ-phage repressor is also reported to induce bending of the promoter DNA, which may facilitate the cooperative binding of the repressor to the second binding site. In the case of genes of eukaryotes, several transcription factors bind to the upstream region or enhancer region of a gene and induce bending that may facilitate contact with basic transcription factors or RNA polymerase itself. Recently, X-ray analysis revealed that TBP (TATA binding protein), a subunit of TFIID, binds to TATA box DNA and induces not only the bending of DNA, but also partial unwinding of the DNA. This may lead to the formation of single-strand template DNA for the transcription by RNA polymerase II.