Authors:

Nikki Chun

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About Paper:

MYC is a highly deregulated oncogene in many human cancers but is hard to directly target at the protein level due to its intrinsically disordered structure. An alternative strategy to target MYC is to lower its cellular levels by reducing its expression. The proximal promoter region of MYC contains a guanine-rich sequence that forms a G-quadruplex (G4) under physiologically relevant conditions. The highly stable MYC promoter G- quadruplex (MycG4) acts as a transcriptional silencer and needs to be actively resolved in cells. DDX5, a DEAD-box helicase protein, can unfold the MycG4 and transactivate MYC transcription. Therefore, the DDX5-MycG4 interaction presents a promising molecular target for downregulating MYC and anti-cancer therapy. However, little is known about how DDX5 binds and unfolds the MycG4. DDX5 is comprised of two main helicase core domains which are flanked by several N and C- terminal disordered domains. Through characterizing the role of each DDX5 domain in MycG4 unfolding, we can understand how DDX5 recognizes and unfolds the MycG4. We have designed, expressed, and purified different truncations of DDX5 protein and tested their activity using a FRET-based G4 unfolding assay to examine the role of each protein domain in G4 unfolding. The results of this study provide a basis for understanding the mechanism of DDX5 unfolding the MycG4 and will guide the design of DDX5 truncation proteins as ideal candidates for future structure determination of the DDX5-MycG4 complex. Keywords: [no keywords provided]

Source:

Purdue University / 2025

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Co-authors:

Nikki Chun