EBP-80, a transcription factor closely resembling the human autoantigen Ku, recognizes single- to double-strand transitions in DNA.

摘要: We have previously reported the purification and characterization of transcription factor EBP-80 (Falzon, M., Kuff, E. L. (1989) J. Biol. Chem. 264, 21915-21922). mediates DNA methylation effect on from an endogenous proviral long terminal repeat. Here we show that is very similar if not identical to Ku autoantigen, a heterodimeric nuclear protein first detected by antibodies autoimmune patients (Mimori, T., Akizuki, Yamagata, H., Inada, S., Yoshida, Homma, M. (1981) Clin. Invest. 68, 611-620). A number laboratories shown complex binds free double-stranded ends. In this study, examined binding properties EBP-80. single-stranded with low affinity. Binding random sequence depends length duplex optimal oligomers 30 32 base pairs; complexes formed these Kd values 15-20 pM. It comparable high affinities blunt-ended DNA, ending in hairpin loops, constructs which internal segment flanked single-strand extensions. also interacts effectively circular molecules containing 30-nucleotide region (gap) or nonhomology (bubble), but only weakly corresponding closed construct made up entirely DNA. prefers A/T G/C The are consistent hypothesis recognizes single- double-strand transitions model presented for interaction its target