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Myc/Max and other helix-loop-helix/leucine zipper proteins bend DNA toward the minor groove

D E Fisher1, L A Parent, P A Sharp

  • 1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.

Proceedings of the National Academy of Sciences of the United States of America
|December 15, 1992
PubMed

Insights

Basic helix-loop-helix leucine zipper proteins bend DNA toward the minor groove. This DNA bending may influence the function of Myc oncoproteins and related transcription factors.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • A family of DNA-binding proteins features basic, helix-loop-helix, and leucine zipper domains.
  • Myc oncoproteins, Max, USF, TFE3, and TFEB are key members of this protein family.
  • These proteins recognize the DNA sequence CACGTG.

Purpose of the Study:

  • To investigate the DNA-binding conformation of basic/helix-loop-helix/leucine zipper proteins.
  • To determine how these proteins affect DNA structure upon binding.

Main Methods:

  • Circular permutation assay was used to analyze DNA conformation in protein-DNA complexes.
  • Phasing analysis was employed to determine the orientation of DNA bending.

Main Results:

  • All tested basic/helix-loop-helix/leucine zipper proteins induced significant DNA bending.
  • DNA bending was consistently oriented towards the minor groove.
  • In-phase spacing of binding sites suggests potential for triple-bended DNA structures.

Conclusions:

  • Basic/helix-loop-helix/leucine zipper proteins induce a similar degree and orientation of DNA bending.
  • This DNA bending mechanism may be crucial for the regulatory functions of these proteins, including Myc.
  • Potential formation of unusual DNA structures has implications for gene regulation.

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