DNA binding of polyomavirus large T-antigen:: kinetics of interactions with different types of binding sites

Polyomavirus large T-antigen binds to GRGGC sites in double-stranded viral DNA, regulating transcription and replication, Using surface plasmon resonance to record interactions of large T-antigen with different types of binding sites, we found that the configuration of recognition motifs influenced both the association and dissociation rates, Particularly, the complex formed at the origin of DNA replication was labile, A comparison of the interactions between targe T-antigen and binding sites with one, two and four GRGGC motifs in tandem showed a strong preference for dimer binding, without detectable co-operativity between dimers, Sodium chloride stabilised the complexes, whereas the dissociation increased rapidly by increasing pH above 7.0. (C) 1998 Federation of European Biochemical Societies.