Structural basis for DNA bending by the architectural transcription factor LEF-1

Area of Science:

• Molecular Biology
• Structural Biology
• Genetics

Background:

• Lymphoid enhancer-binding factor (LEF-1) and T-cell factor 1 (TCF-1) are crucial sequence-specific DNA-binding proteins.
• These proteins regulate critical processes like organogenesis and thymocyte differentiation.
• LEF-1 influences T cell receptor (TCR)-alpha gene enhancers by inducing DNA bending and mediating interactions with other transcription factors.

Purpose of the Study:

• To elucidate the structural basis of LEF-1's DNA binding and regulatory function.
• To determine how the LEF-1 high-mobility-group (HMG) domain interacts with its cognate DNA sequence.

Main Methods:

• Solution structure determination of the LEF-1 HMG domain and adjacent basic region complexed with DNA.
• Analysis of DNA bending and protein-DNA interactions within the complex.

Main Results:

• The HMG domain binds to the widened minor groove of the DNA.
• The DNA double helix is significantly distorted and bent upon LEF-1 binding.
• The adjacent basic region interacts with the narrowed major groove, contributing to DNA recognition.

Conclusions:

• LEF-1 utilizes its HMG domain to induce significant DNA bending, playing an architectural role in gene regulation.
• The combined action of the HMG domain and basic region enables specific DNA recognition and facilitates the assembly of regulatory nucleoprotein complexes.