Multiple Interactions of the Oct-1 (POU2F1) Transcription Factor with PORE and MORE Sites

Resumo

The Oct-1 (POU2F1) transcription factor is one of the most important regulatory proteins in humans and other mammals. An increase in Oct-1 aids the resistance to oxidative and cytotoxic stresses and radiation exposure. A high level of Oct-1 is found in many human tumors and correlates with low survival. Oct-1 interacts with its binding sites as a monomer, a homodimer, or a multimer. The nucleotide sequence of the Oct-1 binding site determines the character of interaction and the conformation of Oct-1 on target DNA, thus influencing the binding of Oct-1 co-repressors and co-activators. Nucleotide substitutions were introduced in all positions of the PORE and MORE sequences and tested for effect on the Oct-1 capability of forming monomeric and dimeric DNA–protein complexes. The position and nature of nucleotide substitutions were found to affect the type of Oct-1 binding to DNA. Several substitutions suppressed the formation of dimers, while others stimulated the process. Certain nucleotide substitutions completely prevented the binding of both monomers and dimers. The Oct-1 concentration in the cell is another factor that affects the character of DNA–protein interactions. Based on the results, the nature and affinity of interaction with Oct-1 is possible to predict from the nucleotide sequence for PORE and MORE sites of the human genome.