119 Exploring G-quadruplex Binding by the C-terminal Zinc Fingers of the Methyl-CpG Binding Protein ZBTB4

Faculty Mentor: Bethany A. Buck (Chemistry, University of Utah)

ZBTB4 belongs to a family of methyl-CpG binding proteins (MBPs) capable of providing selective epigenetic readout to modulate transcriptional processes. ZBTB4 contains two separated zinc finger (ZF) domains; the N-terminal (N-term) domain which is conserved with the other two members of the ZBTB MBPs, is well characterized to participate in selective methylated DNA readout. Until recently, the binding partner(s) and role of the C-terminal (C-term) ZF domain was undefined. We recently determined that the ZBTB4 C-term ZFs exhibit a broad nucleic acid binding scope. Specifically, we found that the ZBTB4 C-term ZFs recognize double stranded DNA, as well as non-canonical G-quadruplex (G4) and hairpin (hp) DNA motifs. Solution NMR and electrophoretic mobility gel shift assays (EMSAs) were used to characterize binding interactions of the ZBTB4 C-term ZFs to G4, hairpin, and double stranded DNA. It was determined that the ZBTB4 C-term ZFs have differential binding interactions with these various DNA motifs and suggests there may be a preference for interactions with the noncanonical DNA motifs. Characterization of the nucleic acid binding partners for the ZBTB4 C-term ZFs expands understanding for the mechanisms by which ZBTB4 mediates transcriptional processes in normal and disease states.