Differential dimer activities of the transcription factor Oct-1 by DNA-Induced interface swapping

Two crystal structures of Oct-1 POU domain bound to DNA provide a rationale for differential, conformation-dependent recruitment of transcription cofa ctors. The POU-homeo and POU-specific subdomains of Oct-1 contain two diffe rent nonoverlapping pairs of surface patches that are capable of forming un related protein-protein interfaces. Members of the POU factor family contai n one or two conserved sequence motifs in the interface that are known to b e phosphorylated, as noted for Oct-1 and Pit-1. Modeling of Oct-4 reveals t he unique case where the same conserved sequence is located in both interfa ces. Our studies provide the basis for two distinct dimeric POU factor arra ngements that are dictated by the architecture of each DNA response element . We suggest interface swapping in dimers could be a general mechanism of m odulating the activity of transcription factors.