Structural Basis for Dimerization and DNA Binding of Transcription Factor FLI1

Area of Science:

• Molecular biology
• Structural biology
• Cancer research

Background:

• Friend leukemia integration 1 (FLI1) is a transcription factor implicated in various cancers.
• Gene rearrangements create oncogenic FLI1 fusions that reprogram host cells.
• FLI1 fusions' interactions are key to their oncogenic roles and potential drug targets.

Purpose of the Study:

• To elucidate the structural basis of FLI1 DNA binding domain (DBD) function.
• To investigate the role of FLI1 DBD dimerization in oncogenic activity.
• To identify potential therapeutic strategies targeting FLI1 in cancer.

Main Methods:

• X-ray crystallography was used to determine the structure of the FLI1 DBD.
• The FLI1 DBD was analyzed alone and bound to DNA.
• Site-directed mutagenesis was employed to study the role of specific residues in dimerization.

Main Results:

• Crystal structures revealed a previously unrecognized homodimer of the FLI1 DBD.
• The dimerization interface involves helix-swapping and hydrophobic interactions, notably Phe362.
• Mutating Phe362 disrupted dimerization without affecting DNA binding or structure.

Conclusions:

• FLI1 DBD dimerization is essential for its oncogenic transcriptional reprogramming.
• Dimerization likely plays a role in both transcriptional activation and repression by FLI1 and its oncogenic fusions.
• Targeting FLI1 DBD dimerization presents a promising strategy for novel anticancer drug development.