Title: Anchoring Hepatitis B: Investigation of HBV promoter binding with zinc finger Specificity protein 1 and G4-quadruplex binding drugs
Background: The G4-quadruplex (G4Q) in a key HBV promoter region is a promising target in drug design. It recruits host zinc finger Specificity protein 1 (Sp1) for transcription. G4Q binding drugs may be able to interfere with this interaction.
Purpose: To elucidate which G4Q nucleic acids interact with Sp1 and how G4Q binders affect this interaction.
Method: Full-length Sp1 (Sp1-FL), Sp1-zinc finger region (Sp1-ZnF region) and each zinc finger were cloned, produced and purified. Interaction strengths (Kd) between the proteins and a folded WT or mutant HBV G4Q were acquired via MST (microscale thermophoresis).
Result(s): Between the HBV WT G4Q and one mutant with MST, Kds for both were similar for Sp1 fragments (~2.5 uM). With Sp1-FL, Kds were 3.33 ± 0.50 uM for WT and 8.50 ± 1.14 uM for the mutant. G4Q binders preliminarily appear to increase binding.
Conclusion(s): The HBV WT G4Q and the mutant G4Q bind with Sp1. More binding studies are required to further understanding.