Zinc induces a bend within the transcription factor IIIA-binding region of the 5 S RNA gene.

Abstract

Binding of Zn2+ to the 5 S RNA gene sequence of Xenopus borealis results in strong bending of the DNA, as inferred from transient electric birefringence data. The effect is specific for Zn2+; several other divalent ions are not able to induce a bend of a similar magnitude. Using five different fragments that span the binding sequence, we are able to estimate a bend magnitude of at least 55 degrees centered at base-pair +65 within the gene. This places the bend within the binding domain of the gene-regulatory protein transcription factor (TF) IIIA. Recent evidence has shown that the protein-DNA complex is also bent. Although our data do not allow us directly to link the two bends, our results suggest that TFIIIA could form a folded structure by stabilizing the same bent conformation that is induced by binding of Zn2+. The chemistry of Zn2+ binding to DNA, and the sequence around the bend center, suggest that the bend is most probably caused by joint co-ordination of Zn2+ to the N-7 groups of stacked purine residues.

• Authors: J Nickol, D C Rau
• Journal: Journal of molecular biology (J Mol Biol) Vol. 228 Issue 4 Pg. 1115-23 (Dec 20 1992) ISSN: 0022-2836 [Print] Netherlands
• PMID: 1474581 (Publication Type: Journal Article)

Chemical References

• Cations, Divalent
• DNA, Ribosomal
• Macromolecular Substances
• Metals
• RNA, Ribosomal, 5S
• Transcription Factor TFIIIA
• Transcription Factors
• Zinc

Topics

• Animals
• Base Sequence
• Birefringence
• Cations, Divalent (pharmacology)
• DNA, Ribosomal (drug effects)
• Dose-Response Relationship, Drug
• Macromolecular Substances
• Metals (pharmacology)
• Molecular Sequence Data
• Nucleic Acid Conformation (drug effects)
• RNA, Ribosomal, 5S (genetics)
• Transcription Factor TFIIIA
• Transcription Factors (metabolism)
• Xenopus
• Zinc (pharmacology)