Sp1 binds to the precise locus of end processing within the terminal repeats of Epstein-Barr virus DNA

Abstract

Interconversion between the linear genome of Epstein-Barr virus (EBV) present in virions and intracellular circular EBV DNA is a novel DNA recombination process. A previously characterized DNA binding activity called terminal repeat or tandem repeat binding protein (TRBP) was found to recognize several G-rich recombinogenic sequences in the EBV genome and in cellular DNA, TRBP was also found to be an autoantigen recognized by sera from certain patients with undifferentiated connective-tissue disorders. Here the transcription factor Sp1 has been identified as a component of TRBP and has been shown to be an autoantigen. Sp1 bound to recombination junctions of EBV DNA, such as those in the terminal repeats and in the large internal repeats, as well as to recombinogenic regions of cellular DNA, such as variable-number tandem repeats and switch regions of the immunoglobulin genes. We defined the ends of the linear EBV genome present in virions and showed that Sp1 binds to the sequence (GGGGTGGGGCATGGG) within EBV terminal repeats at the precise locus of interconversion of linear and circular viral DNA. Sp1 may be involved in DNA recombination.