Expression and purification of the leucine zipper and DNA-binding domains of Fos and Jun: both Fos and Jun contact DNA directly.

摘要: Abstract The protein products of the fos and jun protooncogenes interact cooperatively in form a heterodimer with activator 1 (AP-1) regulatory element. To characterize properties these proteins, we have expressed polypeptides comprised dimerization DNA-binding domains Fos Jun Escherichia coli. The mini-Fos (wbFos) mini-Jun (wbJun) proteins were purified to apparent homogeneity by using nickel affinity chromatography procedure. Purified wbFos wbJun associated rapidly vitro interacted human metallothionein IIA AP-1-binding site. However, efficient DNA binding wbFos-wbJun complexes required an additional activity present nuclear extracts. This was sensitive alkylating agents could be partially mimicked presence reducing stabilizing agents. DNase I footprinting experiments demonstrated that homodimeric Fos-Jun heterodimeric same site on gene. Moreover, UV-crosslinking studies contact directly both equivalently either strand