Functional Dissection of the α and β Subunits of Transcription Factor PEBP2 and the Redox Susceptibility of Its DNA Binding Activity

The mouse transcription factor PEBP2 is a heterodimer of two subunits: a DNA binding subunit α and its partner subunit β. The α subunit shares a region of high homology, termed the Runt domain, with the products of the Drosophila melanogaster segmentation gene runt and the human acute myeloid leukemia-related gene AML1. To study the molecular basis for the DNA binding and heterodimerization functions of this factor, we constructed series of deletions of the α and β subunits and examined their activities by electrophoretic mobility shift and affinity column assays. The minimal functional region of the α subunit for DNA binding and dimerization was shown to coincide with the Runt domain. On the other hand, the region of the β subunit required for heterodimerization was localized to the N-terminal 135 amino acids. Furthermore, it was found that the DNA binding activity of the Runt domain is regulated by a reduction/oxidization (redox) mechanism and that its reductively activated state, which is extremely labile, is stabilized by the β subunit. These findings add a new layer to the mechanism and significance of the regulatory interplay between the two subunits of PEBP2. The mouse transcription factor PEBP2 is a heterodimer of two subunits: a DNA binding subunit α and its partner subunit β. The α subunit shares a region of high homology, termed the Runt domain, with the products of the Drosophila melanogaster segmentation gene runt and the human acute myeloid leukemia-related gene AML1. To study the molecular basis for the DNA binding and heterodimerization functions of this factor, we constructed series of deletions of the α and β subunits and examined their activities by electrophoretic mobility shift and affinity column assays. The minimal functional region of the α subunit for DNA binding and dimerization was shown to coincide with the Runt domain. On the other hand, the region of the β subunit required for heterodimerization was localized to the N-terminal 135 amino acids. Furthermore, it was found that the DNA binding activity of the Runt domain is regulated by a reduction/oxidization (redox) mechanism and that its reductively activated state, which is extremely labile, is stabilized by the β subunit. These findings add a new layer to the mechanism and significance of the regulatory interplay between the two subunits of PEBP2.